2005-04-16 15:20:36 -07:00
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2013-06-19 14:19:33 +05:30
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2005-04-16 15:20:36 -07:00
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2005-10-30 14:59:54 -08:00
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2006-02-28 00:43:23 -05:00
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2006-03-05 03:37:23 -05:00
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2005-10-30 14:59:54 -08:00
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2005-04-16 15:20:36 -07:00
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2012-10-23 01:29:03 +02:00
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2013-08-06 22:53:03 +05:30
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2005-04-16 15:20:36 -07:00
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2013-08-06 22:53:03 +05:30
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2006-01-13 15:54:22 -08:00
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2013-08-06 22:53:03 +05:30
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2014-03-04 11:00:26 +08:00
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2014-12-23 22:09:48 -08:00
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2013-08-06 22:53:03 +05:30
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2010-04-20 13:17:36 +02:00
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2015-01-27 14:06:08 +05:30
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2015-05-12 12:20:11 +05:30
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2016-02-21 12:53:12 -06:00
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2015-05-12 12:20:11 +05:30
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2015-01-27 14:06:08 +05:30
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2015-01-27 14:06:09 +05:30
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2005-04-16 15:20:36 -07:00
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2006-08-11 17:59:28 -04:00
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2005-04-16 15:20:36 -07:00
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2013-04-29 00:08:16 +02:00
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2008-03-25 15:06:53 -07:00
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2013-06-19 14:19:33 +05:30
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2014-03-04 11:00:26 +08:00
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2005-04-16 15:20:36 -07:00
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2013-10-25 19:45:48 +05:30
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2005-04-16 15:20:36 -07:00
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2015-01-02 12:34:29 +05:30
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2016-05-14 01:01:46 +02:00
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2016-03-21 15:45:24 +01:00
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2016-05-14 01:01:46 +02:00
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2016-05-12 15:14:12 +02:00
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2005-04-16 15:20:36 -07:00
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2006-02-28 00:43:23 -05:00
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2005-04-16 15:20:36 -07:00
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[PATCH] Notifier chain update: API changes
The kernel's implementation of notifier chains is unsafe. There is no
protection against entries being added to or removed from a chain while the
chain is in use. The issues were discussed in this thread:
http://marc.theaimsgroup.com/?l=linux-kernel&m=113018709002036&w=2
We noticed that notifier chains in the kernel fall into two basic usage
classes:
"Blocking" chains are always called from a process context
and the callout routines are allowed to sleep;
"Atomic" chains can be called from an atomic context and
the callout routines are not allowed to sleep.
We decided to codify this distinction and make it part of the API. Therefore
this set of patches introduces three new, parallel APIs: one for blocking
notifiers, one for atomic notifiers, and one for "raw" notifiers (which is
really just the old API under a new name). New kinds of data structures are
used for the heads of the chains, and new routines are defined for
registration, unregistration, and calling a chain. The three APIs are
explained in include/linux/notifier.h and their implementation is in
kernel/sys.c.
With atomic and blocking chains, the implementation guarantees that the chain
links will not be corrupted and that chain callers will not get messed up by
entries being added or removed. For raw chains the implementation provides no
guarantees at all; users of this API must provide their own protections. (The
idea was that situations may come up where the assumptions of the atomic and
blocking APIs are not appropriate, so it should be possible for users to
handle these things in their own way.)
There are some limitations, which should not be too hard to live with. For
atomic/blocking chains, registration and unregistration must always be done in
a process context since the chain is protected by a mutex/rwsem. Also, a
callout routine for a non-raw chain must not try to register or unregister
entries on its own chain. (This did happen in a couple of places and the code
had to be changed to avoid it.)
Since atomic chains may be called from within an NMI handler, they cannot use
spinlocks for synchronization. Instead we use RCU. The overhead falls almost
entirely in the unregister routine, which is okay since unregistration is much
less frequent that calling a chain.
Here is the list of chains that we adjusted and their classifications. None
of them use the raw API, so for the moment it is only a placeholder.
ATOMIC CHAINS
-------------
arch/i386/kernel/traps.c: i386die_chain
arch/ia64/kernel/traps.c: ia64die_chain
arch/powerpc/kernel/traps.c: powerpc_die_chain
arch/sparc64/kernel/traps.c: sparc64die_chain
arch/x86_64/kernel/traps.c: die_chain
drivers/char/ipmi/ipmi_si_intf.c: xaction_notifier_list
kernel/panic.c: panic_notifier_list
kernel/profile.c: task_free_notifier
net/bluetooth/hci_core.c: hci_notifier
net/ipv4/netfilter/ip_conntrack_core.c: ip_conntrack_chain
net/ipv4/netfilter/ip_conntrack_core.c: ip_conntrack_expect_chain
net/ipv6/addrconf.c: inet6addr_chain
net/netfilter/nf_conntrack_core.c: nf_conntrack_chain
net/netfilter/nf_conntrack_core.c: nf_conntrack_expect_chain
net/netlink/af_netlink.c: netlink_chain
BLOCKING CHAINS
---------------
arch/powerpc/platforms/pseries/reconfig.c: pSeries_reconfig_chain
arch/s390/kernel/process.c: idle_chain
arch/x86_64/kernel/process.c idle_notifier
drivers/base/memory.c: memory_chain
drivers/cpufreq/cpufreq.c cpufreq_policy_notifier_list
drivers/cpufreq/cpufreq.c cpufreq_transition_notifier_list
drivers/macintosh/adb.c: adb_client_list
drivers/macintosh/via-pmu.c sleep_notifier_list
drivers/macintosh/via-pmu68k.c sleep_notifier_list
drivers/macintosh/windfarm_core.c wf_client_list
drivers/usb/core/notify.c usb_notifier_list
drivers/video/fbmem.c fb_notifier_list
kernel/cpu.c cpu_chain
kernel/module.c module_notify_list
kernel/profile.c munmap_notifier
kernel/profile.c task_exit_notifier
kernel/sys.c reboot_notifier_list
net/core/dev.c netdev_chain
net/decnet/dn_dev.c: dnaddr_chain
net/ipv4/devinet.c: inetaddr_chain
It's possible that some of these classifications are wrong. If they are,
please let us know or submit a patch to fix them. Note that any chain that
gets called very frequently should be atomic, because the rwsem read-locking
used for blocking chains is very likely to incur cache misses on SMP systems.
(However, if the chain's callout routines may sleep then the chain cannot be
atomic.)
The patch set was written by Alan Stern and Chandra Seetharaman, incorporating
material written by Keith Owens and suggestions from Paul McKenney and Andrew
Morton.
[jes@sgi.com: restructure the notifier chain initialization macros]
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Chandra Seetharaman <sekharan@us.ibm.com>
Signed-off-by: Jes Sorensen <jes@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-27 01:16:30 -08:00
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2006-10-04 02:17:06 -07:00
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2005-04-16 15:20:36 -07:00
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2008-02-16 08:41:24 -02:00
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2006-10-04 02:17:06 -07:00
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2008-02-16 08:41:24 -02:00
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2006-10-04 02:17:06 -07:00
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2006-11-20 11:47:18 -08:00
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2005-04-16 15:20:36 -07:00
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2012-03-13 19:18:39 -04:00
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2012-10-26 00:51:32 +02:00
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2012-03-13 19:18:39 -04:00
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2009-01-18 01:37:11 -05:00
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2005-04-16 15:20:36 -07:00
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2013-03-27 15:58:58 +00:00
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2013-10-02 14:13:18 +05:30
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2013-03-27 15:58:58 +00:00
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2013-05-16 05:09:56 +00:00
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2013-03-27 15:58:58 +00:00
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2013-05-16 05:09:57 +00:00
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2013-05-17 11:26:32 +00:00
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2017-01-31 04:09:19 +01:00
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2013-05-17 11:26:32 +00:00
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2017-01-31 04:09:19 +01:00
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2013-05-17 11:26:32 +00:00
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2017-01-31 04:09:19 +01:00
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2013-05-17 11:26:32 +00:00
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2013-10-03 20:29:07 +05:30
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2015-05-22 22:48:22 +05:30
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2013-10-03 20:29:07 +05:30
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2015-09-16 02:17:49 +02:00
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2014-01-09 20:38:43 +05:30
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2015-05-08 11:53:45 +05:30
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2015-09-16 02:17:49 +02:00
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2015-05-08 11:53:45 +05:30
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2014-01-09 20:38:43 +05:30
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2014-03-11 10:03:00 -07:00
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2014-01-09 20:38:43 +05:30
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2015-02-19 17:02:03 +05:30
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2013-08-06 22:53:11 +05:30
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2005-04-16 15:20:36 -07:00
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2013-08-06 22:53:11 +05:30
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2005-04-16 15:20:36 -07:00
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2015-02-19 17:02:05 +05:30
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2013-08-06 22:53:11 +05:30
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2005-04-16 15:20:36 -07:00
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2013-02-22 16:24:34 +00:00
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2005-04-16 15:20:36 -07:00
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2013-08-06 22:53:11 +05:30
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2015-05-08 11:53:45 +05:30
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2013-08-06 22:53:11 +05:30
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2013-04-29 00:08:16 +02:00
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2013-08-06 22:53:11 +05:30
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2005-04-16 15:20:36 -07:00
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2013-08-06 22:53:05 +05:30
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2012-07-20 18:14:38 +00:00
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2005-04-16 15:20:36 -07:00
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2015-02-19 17:02:03 +05:30
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2013-08-06 22:53:05 +05:30
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2005-04-16 15:20:36 -07:00
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2013-08-06 22:53:11 +05:30
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2005-04-16 15:20:36 -07:00
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2006-02-28 00:43:23 -05:00
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2005-04-16 15:20:36 -07:00
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2006-01-14 13:20:43 -08:00
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2005-04-16 15:20:36 -07:00
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2015-01-02 12:34:34 +05:30
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2005-04-16 15:20:36 -07:00
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2014-03-11 10:03:00 -07:00
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2005-04-16 15:20:36 -07:00
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2014-03-19 11:24:58 +05:30
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2006-10-26 16:20:58 +05:30
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2014-03-11 10:03:00 -07:00
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2005-04-16 15:20:36 -07:00
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2015-01-02 12:34:34 +05:30
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2005-04-16 15:20:36 -07:00
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2013-06-19 14:19:34 +05:30
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2013-03-24 11:56:43 +05:30
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2005-04-16 15:20:36 -07:00
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2013-01-17 16:22:21 +00:00
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2013-04-29 00:08:16 +02:00
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2011-03-27 15:04:46 +02:00
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2014-03-11 10:03:00 -07:00
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2005-04-16 15:20:36 -07:00
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2006-01-31 15:53:55 -08:00
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2005-04-16 15:20:36 -07:00
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2006-02-28 00:43:23 -05:00
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2006-01-31 15:53:55 -08:00
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2013-04-29 00:08:16 +02:00
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2006-01-31 15:53:55 -08:00
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2014-03-11 10:03:00 -07:00
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2006-01-31 15:53:55 -08:00
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2005-04-16 15:20:36 -07:00
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2006-10-04 02:17:06 -07:00
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[PATCH] Notifier chain update: API changes
The kernel's implementation of notifier chains is unsafe. There is no
protection against entries being added to or removed from a chain while the
chain is in use. The issues were discussed in this thread:
http://marc.theaimsgroup.com/?l=linux-kernel&m=113018709002036&w=2
We noticed that notifier chains in the kernel fall into two basic usage
classes:
"Blocking" chains are always called from a process context
and the callout routines are allowed to sleep;
"Atomic" chains can be called from an atomic context and
the callout routines are not allowed to sleep.
We decided to codify this distinction and make it part of the API. Therefore
this set of patches introduces three new, parallel APIs: one for blocking
notifiers, one for atomic notifiers, and one for "raw" notifiers (which is
really just the old API under a new name). New kinds of data structures are
used for the heads of the chains, and new routines are defined for
registration, unregistration, and calling a chain. The three APIs are
explained in include/linux/notifier.h and their implementation is in
kernel/sys.c.
With atomic and blocking chains, the implementation guarantees that the chain
links will not be corrupted and that chain callers will not get messed up by
entries being added or removed. For raw chains the implementation provides no
guarantees at all; users of this API must provide their own protections. (The
idea was that situations may come up where the assumptions of the atomic and
blocking APIs are not appropriate, so it should be possible for users to
handle these things in their own way.)
There are some limitations, which should not be too hard to live with. For
atomic/blocking chains, registration and unregistration must always be done in
a process context since the chain is protected by a mutex/rwsem. Also, a
callout routine for a non-raw chain must not try to register or unregister
entries on its own chain. (This did happen in a couple of places and the code
had to be changed to avoid it.)
Since atomic chains may be called from within an NMI handler, they cannot use
spinlocks for synchronization. Instead we use RCU. The overhead falls almost
entirely in the unregister routine, which is okay since unregistration is much
less frequent that calling a chain.
Here is the list of chains that we adjusted and their classifications. None
of them use the raw API, so for the moment it is only a placeholder.
ATOMIC CHAINS
-------------
arch/i386/kernel/traps.c: i386die_chain
arch/ia64/kernel/traps.c: ia64die_chain
arch/powerpc/kernel/traps.c: powerpc_die_chain
arch/sparc64/kernel/traps.c: sparc64die_chain
arch/x86_64/kernel/traps.c: die_chain
drivers/char/ipmi/ipmi_si_intf.c: xaction_notifier_list
kernel/panic.c: panic_notifier_list
kernel/profile.c: task_free_notifier
net/bluetooth/hci_core.c: hci_notifier
net/ipv4/netfilter/ip_conntrack_core.c: ip_conntrack_chain
net/ipv4/netfilter/ip_conntrack_core.c: ip_conntrack_expect_chain
net/ipv6/addrconf.c: inet6addr_chain
net/netfilter/nf_conntrack_core.c: nf_conntrack_chain
net/netfilter/nf_conntrack_core.c: nf_conntrack_expect_chain
net/netlink/af_netlink.c: netlink_chain
BLOCKING CHAINS
---------------
arch/powerpc/platforms/pseries/reconfig.c: pSeries_reconfig_chain
arch/s390/kernel/process.c: idle_chain
arch/x86_64/kernel/process.c idle_notifier
drivers/base/memory.c: memory_chain
drivers/cpufreq/cpufreq.c cpufreq_policy_notifier_list
drivers/cpufreq/cpufreq.c cpufreq_transition_notifier_list
drivers/macintosh/adb.c: adb_client_list
drivers/macintosh/via-pmu.c sleep_notifier_list
drivers/macintosh/via-pmu68k.c sleep_notifier_list
drivers/macintosh/windfarm_core.c wf_client_list
drivers/usb/core/notify.c usb_notifier_list
drivers/video/fbmem.c fb_notifier_list
kernel/cpu.c cpu_chain
kernel/module.c module_notify_list
kernel/profile.c munmap_notifier
kernel/profile.c task_exit_notifier
kernel/sys.c reboot_notifier_list
net/core/dev.c netdev_chain
net/decnet/dn_dev.c: dnaddr_chain
net/ipv4/devinet.c: inetaddr_chain
It's possible that some of these classifications are wrong. If they are,
please let us know or submit a patch to fix them. Note that any chain that
gets called very frequently should be atomic, because the rwsem read-locking
used for blocking chains is very likely to incur cache misses on SMP systems.
(However, if the chain's callout routines may sleep then the chain cannot be
atomic.)
The patch set was written by Alan Stern and Chandra Seetharaman, incorporating
material written by Keith Owens and suggestions from Paul McKenney and Andrew
Morton.
[jes@sgi.com: restructure the notifier chain initialization macros]
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Chandra Seetharaman <sekharan@us.ibm.com>
Signed-off-by: Jes Sorensen <jes@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-27 01:16:30 -08:00
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2005-04-16 15:20:36 -07:00
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2006-01-31 15:53:55 -08:00
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2005-04-16 15:20:36 -07:00
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2014-03-11 10:03:00 -07:00
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2011-01-03 17:50:44 +01:00
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2016-05-31 22:14:44 +02:00
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2006-10-04 02:17:06 -07:00
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[PATCH] Notifier chain update: API changes
The kernel's implementation of notifier chains is unsafe. There is no
protection against entries being added to or removed from a chain while the
chain is in use. The issues were discussed in this thread:
http://marc.theaimsgroup.com/?l=linux-kernel&m=113018709002036&w=2
We noticed that notifier chains in the kernel fall into two basic usage
classes:
"Blocking" chains are always called from a process context
and the callout routines are allowed to sleep;
"Atomic" chains can be called from an atomic context and
the callout routines are not allowed to sleep.
We decided to codify this distinction and make it part of the API. Therefore
this set of patches introduces three new, parallel APIs: one for blocking
notifiers, one for atomic notifiers, and one for "raw" notifiers (which is
really just the old API under a new name). New kinds of data structures are
used for the heads of the chains, and new routines are defined for
registration, unregistration, and calling a chain. The three APIs are
explained in include/linux/notifier.h and their implementation is in
kernel/sys.c.
With atomic and blocking chains, the implementation guarantees that the chain
links will not be corrupted and that chain callers will not get messed up by
entries being added or removed. For raw chains the implementation provides no
guarantees at all; users of this API must provide their own protections. (The
idea was that situations may come up where the assumptions of the atomic and
blocking APIs are not appropriate, so it should be possible for users to
handle these things in their own way.)
There are some limitations, which should not be too hard to live with. For
atomic/blocking chains, registration and unregistration must always be done in
a process context since the chain is protected by a mutex/rwsem. Also, a
callout routine for a non-raw chain must not try to register or unregister
entries on its own chain. (This did happen in a couple of places and the code
had to be changed to avoid it.)
Since atomic chains may be called from within an NMI handler, they cannot use
spinlocks for synchronization. Instead we use RCU. The overhead falls almost
entirely in the unregister routine, which is okay since unregistration is much
less frequent that calling a chain.
Here is the list of chains that we adjusted and their classifications. None
of them use the raw API, so for the moment it is only a placeholder.
ATOMIC CHAINS
-------------
arch/i386/kernel/traps.c: i386die_chain
arch/ia64/kernel/traps.c: ia64die_chain
arch/powerpc/kernel/traps.c: powerpc_die_chain
arch/sparc64/kernel/traps.c: sparc64die_chain
arch/x86_64/kernel/traps.c: die_chain
drivers/char/ipmi/ipmi_si_intf.c: xaction_notifier_list
kernel/panic.c: panic_notifier_list
kernel/profile.c: task_free_notifier
net/bluetooth/hci_core.c: hci_notifier
net/ipv4/netfilter/ip_conntrack_core.c: ip_conntrack_chain
net/ipv4/netfilter/ip_conntrack_core.c: ip_conntrack_expect_chain
net/ipv6/addrconf.c: inet6addr_chain
net/netfilter/nf_conntrack_core.c: nf_conntrack_chain
net/netfilter/nf_conntrack_core.c: nf_conntrack_expect_chain
net/netlink/af_netlink.c: netlink_chain
BLOCKING CHAINS
---------------
arch/powerpc/platforms/pseries/reconfig.c: pSeries_reconfig_chain
arch/s390/kernel/process.c: idle_chain
arch/x86_64/kernel/process.c idle_notifier
drivers/base/memory.c: memory_chain
drivers/cpufreq/cpufreq.c cpufreq_policy_notifier_list
drivers/cpufreq/cpufreq.c cpufreq_transition_notifier_list
drivers/macintosh/adb.c: adb_client_list
drivers/macintosh/via-pmu.c sleep_notifier_list
drivers/macintosh/via-pmu68k.c sleep_notifier_list
drivers/macintosh/windfarm_core.c wf_client_list
drivers/usb/core/notify.c usb_notifier_list
drivers/video/fbmem.c fb_notifier_list
kernel/cpu.c cpu_chain
kernel/module.c module_notify_list
kernel/profile.c munmap_notifier
kernel/profile.c task_exit_notifier
kernel/sys.c reboot_notifier_list
net/core/dev.c netdev_chain
net/decnet/dn_dev.c: dnaddr_chain
net/ipv4/devinet.c: inetaddr_chain
It's possible that some of these classifications are wrong. If they are,
please let us know or submit a patch to fix them. Note that any chain that
gets called very frequently should be atomic, because the rwsem read-locking
used for blocking chains is very likely to incur cache misses on SMP systems.
(However, if the chain's callout routines may sleep then the chain cannot be
atomic.)
The patch set was written by Alan Stern and Chandra Seetharaman, incorporating
material written by Keith Owens and suggestions from Paul McKenney and Andrew
Morton.
[jes@sgi.com: restructure the notifier chain initialization macros]
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Chandra Seetharaman <sekharan@us.ibm.com>
Signed-off-by: Jes Sorensen <jes@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-27 01:16:30 -08:00
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2006-01-31 15:53:55 -08:00
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2005-04-16 15:20:36 -07:00
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2013-06-19 14:19:33 +05:30
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2013-03-24 11:56:43 +05:30
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2014-03-24 13:35:46 +05:30
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2013-03-24 11:56:43 +05:30
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2005-04-16 15:20:36 -07:00
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2013-12-02 11:04:12 +05:30
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2014-03-24 13:35:46 +05:30
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2013-12-02 11:04:12 +05:30
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cpufreq: Make sure frequency transitions are serialized
Whenever we change the frequency of a CPU, we call the PRECHANGE and POSTCHANGE
notifiers. They must be serialized, i.e. PRECHANGE and POSTCHANGE notifiers
should strictly alternate, thereby preventing two different sets of PRECHANGE or
POSTCHANGE notifiers from interleaving arbitrarily.
The following examples illustrate why this is important:
Scenario 1:
-----------
A thread reading the value of cpuinfo_cur_freq, will call
__cpufreq_cpu_get()->cpufreq_out_of_sync()->cpufreq_notify_transition()
The ondemand governor can decide to change the frequency of the CPU at the same
time and hence it can end up sending the notifications via ->target().
If the notifiers are not serialized, the following sequence can occur:
- PRECHANGE Notification for freq A (from cpuinfo_cur_freq)
- PRECHANGE Notification for freq B (from target())
- Freq changed by target() to B
- POSTCHANGE Notification for freq B
- POSTCHANGE Notification for freq A
We can see from the above that the last POSTCHANGE Notification happens for freq
A but the hardware is set to run at freq B.
Where would we break then?: adjust_jiffies() in cpufreq.c & cpufreq_callback()
in arch/arm/kernel/smp.c (which also adjusts the jiffies). All the
loops_per_jiffy calculations will get messed up.
Scenario 2:
-----------
The governor calls __cpufreq_driver_target() to change the frequency. At the
same time, if we change scaling_{min|max}_freq from sysfs, it will end up
calling the governor's CPUFREQ_GOV_LIMITS notification, which will also call
__cpufreq_driver_target(). And hence we end up issuing concurrent calls to
->target().
Typically, platforms have the following logic in their ->target() routines:
(Eg: cpufreq-cpu0, omap, exynos, etc)
A. If new freq is more than old: Increase voltage
B. Change freq
C. If new freq is less than old: decrease voltage
Now, if the two concurrent calls to ->target() are X and Y, where X is trying to
increase the freq and Y is trying to decrease it, we get the following race
condition:
X.A: voltage gets increased for larger freq
Y.A: nothing happens
Y.B: freq gets decreased
Y.C: voltage gets decreased
X.B: freq gets increased
X.C: nothing happens
Thus we can end up setting a freq which is not supported by the voltage we have
set. That will probably make the clock to the CPU unstable and the system might
not work properly anymore.
This patch introduces a set of synchronization primitives to serialize frequency
transitions, which are to be used as shown below:
cpufreq_freq_transition_begin();
//Perform the frequency change
cpufreq_freq_transition_end();
The _begin() call sends the PRECHANGE notification whereas the _end() call sends
the POSTCHANGE notification. Also, all the necessary synchronization is handled
within these calls. In particular, even drivers which set the ASYNC_NOTIFICATION
flag can also use these APIs for performing frequency transitions (ie., you can
call _begin() from one task, and call the corresponding _end() from a different
task).
The actual synchronization underneath is not that complicated:
The key challenge is to allow drivers to begin the transition from one thread
and end it in a completely different thread (this is to enable drivers that do
asynchronous POSTCHANGE notification from bottom-halves, to also use the same
interface).
To achieve this, a 'transition_ongoing' flag, a 'transition_lock' spinlock and a
wait-queue are added per-policy. The flag and the wait-queue are used in
conjunction to create an "uninterrupted flow" from _begin() to _end(). The
spinlock is used to ensure that only one such "flow" is in flight at any given
time. Put together, this provides us all the necessary synchronization.
Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2014-03-24 13:35:44 +05:30
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cpufreq: Catch double invocations of cpufreq_freq_transition_begin/end
Some cpufreq drivers were redundantly invoking the _begin() and _end()
APIs around frequency transitions, and this double invocation (one from
the cpufreq core and the other from the cpufreq driver) used to result
in a self-deadlock, leading to system hangs during boot. (The _begin()
API makes contending callers wait until the previous invocation is
complete. Hence, the cpufreq driver would end up waiting on itself!).
Now all such drivers have been fixed, but debugging this issue was not
very straight-forward (even lockdep didn't catch this). So let us add a
debug infrastructure to the cpufreq core to catch such issues more easily
in the future.
We add a new field called 'transition_task' to the policy structure, to keep
track of the task which is performing the frequency transition. Using this
field, we make note of this task during _begin() and print a warning if we
find a case where the same task is calling _begin() again, before completing
the previous frequency transition using the corresponding _end().
We have left out ASYNC_NOTIFICATION drivers from this debug infrastructure
for 2 reasons:
1. At the moment, we have no way to avoid a particular scenario where this
debug infrastructure can emit false-positive warnings for such drivers.
The scenario is depicted below:
Task A Task B
/* 1st freq transition */
Invoke _begin() {
...
...
}
Change the frequency
/* 2nd freq transition */
Invoke _begin() {
... //waiting for B to
... //finish _end() for
... //the 1st transition
... | Got interrupt for successful
... | change of frequency (1st one).
... |
... | /* 1st freq transition */
... | Invoke _end() {
... | ...
... V }
...
...
}
This scenario is actually deadlock-free because, once Task A changes the
frequency, it is Task B's responsibility to invoke the corresponding
_end() for the 1st frequency transition. Hence it is perfectly legal for
Task A to go ahead and attempt another frequency transition in the meantime.
(Of course it won't be able to proceed until Task B finishes the 1st _end(),
but this doesn't cause a deadlock or a hang).
The debug infrastructure cannot handle this scenario and will treat it as
a deadlock and print a warning. To avoid this, we exclude such drivers
from the purview of this code.
2. Luckily, we don't _need_ this infrastructure for ASYNC_NOTIFICATION drivers
at all! The cpufreq core does not automatically invoke the _begin() and
_end() APIs during frequency transitions in such drivers. Thus, the driver
alone is responsible for invoking _begin()/_end() and hence there shouldn't
be any conflicts which lead to double invocations. So, we can skip these
drivers, since the probability that such drivers will hit this problem is
extremely low, as outlined above.
Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2014-05-05 12:52:39 +05:30
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cpufreq: Make sure frequency transitions are serialized
Whenever we change the frequency of a CPU, we call the PRECHANGE and POSTCHANGE
notifiers. They must be serialized, i.e. PRECHANGE and POSTCHANGE notifiers
should strictly alternate, thereby preventing two different sets of PRECHANGE or
POSTCHANGE notifiers from interleaving arbitrarily.
The following examples illustrate why this is important:
Scenario 1:
-----------
A thread reading the value of cpuinfo_cur_freq, will call
__cpufreq_cpu_get()->cpufreq_out_of_sync()->cpufreq_notify_transition()
The ondemand governor can decide to change the frequency of the CPU at the same
time and hence it can end up sending the notifications via ->target().
If the notifiers are not serialized, the following sequence can occur:
- PRECHANGE Notification for freq A (from cpuinfo_cur_freq)
- PRECHANGE Notification for freq B (from target())
- Freq changed by target() to B
- POSTCHANGE Notification for freq B
- POSTCHANGE Notification for freq A
We can see from the above that the last POSTCHANGE Notification happens for freq
A but the hardware is set to run at freq B.
Where would we break then?: adjust_jiffies() in cpufreq.c & cpufreq_callback()
in arch/arm/kernel/smp.c (which also adjusts the jiffies). All the
loops_per_jiffy calculations will get messed up.
Scenario 2:
-----------
The governor calls __cpufreq_driver_target() to change the frequency. At the
same time, if we change scaling_{min|max}_freq from sysfs, it will end up
calling the governor's CPUFREQ_GOV_LIMITS notification, which will also call
__cpufreq_driver_target(). And hence we end up issuing concurrent calls to
->target().
Typically, platforms have the following logic in their ->target() routines:
(Eg: cpufreq-cpu0, omap, exynos, etc)
A. If new freq is more than old: Increase voltage
B. Change freq
C. If new freq is less than old: decrease voltage
Now, if the two concurrent calls to ->target() are X and Y, where X is trying to
increase the freq and Y is trying to decrease it, we get the following race
condition:
X.A: voltage gets increased for larger freq
Y.A: nothing happens
Y.B: freq gets decreased
Y.C: voltage gets decreased
X.B: freq gets increased
X.C: nothing happens
Thus we can end up setting a freq which is not supported by the voltage we have
set. That will probably make the clock to the CPU unstable and the system might
not work properly anymore.
This patch introduces a set of synchronization primitives to serialize frequency
transitions, which are to be used as shown below:
cpufreq_freq_transition_begin();
//Perform the frequency change
cpufreq_freq_transition_end();
The _begin() call sends the PRECHANGE notification whereas the _end() call sends
the POSTCHANGE notification. Also, all the necessary synchronization is handled
within these calls. In particular, even drivers which set the ASYNC_NOTIFICATION
flag can also use these APIs for performing frequency transitions (ie., you can
call _begin() from one task, and call the corresponding _end() from a different
task).
The actual synchronization underneath is not that complicated:
The key challenge is to allow drivers to begin the transition from one thread
and end it in a completely different thread (this is to enable drivers that do
asynchronous POSTCHANGE notification from bottom-halves, to also use the same
interface).
To achieve this, a 'transition_ongoing' flag, a 'transition_lock' spinlock and a
wait-queue are added per-policy. The flag and the wait-queue are used in
conjunction to create an "uninterrupted flow" from _begin() to _end(). The
spinlock is used to ensure that only one such "flow" is in flight at any given
time. Put together, this provides us all the necessary synchronization.
Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2014-03-24 13:35:44 +05:30
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cpufreq: Catch double invocations of cpufreq_freq_transition_begin/end
Some cpufreq drivers were redundantly invoking the _begin() and _end()
APIs around frequency transitions, and this double invocation (one from
the cpufreq core and the other from the cpufreq driver) used to result
in a self-deadlock, leading to system hangs during boot. (The _begin()
API makes contending callers wait until the previous invocation is
complete. Hence, the cpufreq driver would end up waiting on itself!).
Now all such drivers have been fixed, but debugging this issue was not
very straight-forward (even lockdep didn't catch this). So let us add a
debug infrastructure to the cpufreq core to catch such issues more easily
in the future.
We add a new field called 'transition_task' to the policy structure, to keep
track of the task which is performing the frequency transition. Using this
field, we make note of this task during _begin() and print a warning if we
find a case where the same task is calling _begin() again, before completing
the previous frequency transition using the corresponding _end().
We have left out ASYNC_NOTIFICATION drivers from this debug infrastructure
for 2 reasons:
1. At the moment, we have no way to avoid a particular scenario where this
debug infrastructure can emit false-positive warnings for such drivers.
The scenario is depicted below:
Task A Task B
/* 1st freq transition */
Invoke _begin() {
...
...
}
Change the frequency
/* 2nd freq transition */
Invoke _begin() {
... //waiting for B to
... //finish _end() for
... //the 1st transition
... | Got interrupt for successful
... | change of frequency (1st one).
... |
... | /* 1st freq transition */
... | Invoke _end() {
... | ...
... V }
...
...
}
This scenario is actually deadlock-free because, once Task A changes the
frequency, it is Task B's responsibility to invoke the corresponding
_end() for the 1st frequency transition. Hence it is perfectly legal for
Task A to go ahead and attempt another frequency transition in the meantime.
(Of course it won't be able to proceed until Task B finishes the 1st _end(),
but this doesn't cause a deadlock or a hang).
The debug infrastructure cannot handle this scenario and will treat it as
a deadlock and print a warning. To avoid this, we exclude such drivers
from the purview of this code.
2. Luckily, we don't _need_ this infrastructure for ASYNC_NOTIFICATION drivers
at all! The cpufreq core does not automatically invoke the _begin() and
_end() APIs during frequency transitions in such drivers. Thus, the driver
alone is responsible for invoking _begin()/_end() and hence there shouldn't
be any conflicts which lead to double invocations. So, we can skip these
drivers, since the probability that such drivers will hit this problem is
extremely low, as outlined above.
Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2014-05-05 12:52:39 +05:30
|
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cpufreq: Make sure frequency transitions are serialized
Whenever we change the frequency of a CPU, we call the PRECHANGE and POSTCHANGE
notifiers. They must be serialized, i.e. PRECHANGE and POSTCHANGE notifiers
should strictly alternate, thereby preventing two different sets of PRECHANGE or
POSTCHANGE notifiers from interleaving arbitrarily.
The following examples illustrate why this is important:
Scenario 1:
-----------
A thread reading the value of cpuinfo_cur_freq, will call
__cpufreq_cpu_get()->cpufreq_out_of_sync()->cpufreq_notify_transition()
The ondemand governor can decide to change the frequency of the CPU at the same
time and hence it can end up sending the notifications via ->target().
If the notifiers are not serialized, the following sequence can occur:
- PRECHANGE Notification for freq A (from cpuinfo_cur_freq)
- PRECHANGE Notification for freq B (from target())
- Freq changed by target() to B
- POSTCHANGE Notification for freq B
- POSTCHANGE Notification for freq A
We can see from the above that the last POSTCHANGE Notification happens for freq
A but the hardware is set to run at freq B.
Where would we break then?: adjust_jiffies() in cpufreq.c & cpufreq_callback()
in arch/arm/kernel/smp.c (which also adjusts the jiffies). All the
loops_per_jiffy calculations will get messed up.
Scenario 2:
-----------
The governor calls __cpufreq_driver_target() to change the frequency. At the
same time, if we change scaling_{min|max}_freq from sysfs, it will end up
calling the governor's CPUFREQ_GOV_LIMITS notification, which will also call
__cpufreq_driver_target(). And hence we end up issuing concurrent calls to
->target().
Typically, platforms have the following logic in their ->target() routines:
(Eg: cpufreq-cpu0, omap, exynos, etc)
A. If new freq is more than old: Increase voltage
B. Change freq
C. If new freq is less than old: decrease voltage
Now, if the two concurrent calls to ->target() are X and Y, where X is trying to
increase the freq and Y is trying to decrease it, we get the following race
condition:
X.A: voltage gets increased for larger freq
Y.A: nothing happens
Y.B: freq gets decreased
Y.C: voltage gets decreased
X.B: freq gets increased
X.C: nothing happens
Thus we can end up setting a freq which is not supported by the voltage we have
set. That will probably make the clock to the CPU unstable and the system might
not work properly anymore.
This patch introduces a set of synchronization primitives to serialize frequency
transitions, which are to be used as shown below:
cpufreq_freq_transition_begin();
//Perform the frequency change
cpufreq_freq_transition_end();
The _begin() call sends the PRECHANGE notification whereas the _end() call sends
the POSTCHANGE notification. Also, all the necessary synchronization is handled
within these calls. In particular, even drivers which set the ASYNC_NOTIFICATION
flag can also use these APIs for performing frequency transitions (ie., you can
call _begin() from one task, and call the corresponding _end() from a different
task).
The actual synchronization underneath is not that complicated:
The key challenge is to allow drivers to begin the transition from one thread
and end it in a completely different thread (this is to enable drivers that do
asynchronous POSTCHANGE notification from bottom-halves, to also use the same
interface).
To achieve this, a 'transition_ongoing' flag, a 'transition_lock' spinlock and a
wait-queue are added per-policy. The flag and the wait-queue are used in
conjunction to create an "uninterrupted flow" from _begin() to _end(). The
spinlock is used to ensure that only one such "flow" is in flight at any given
time. Put together, this provides us all the necessary synchronization.
Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2014-03-24 13:35:44 +05:30
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cpufreq: Catch double invocations of cpufreq_freq_transition_begin/end
Some cpufreq drivers were redundantly invoking the _begin() and _end()
APIs around frequency transitions, and this double invocation (one from
the cpufreq core and the other from the cpufreq driver) used to result
in a self-deadlock, leading to system hangs during boot. (The _begin()
API makes contending callers wait until the previous invocation is
complete. Hence, the cpufreq driver would end up waiting on itself!).
Now all such drivers have been fixed, but debugging this issue was not
very straight-forward (even lockdep didn't catch this). So let us add a
debug infrastructure to the cpufreq core to catch such issues more easily
in the future.
We add a new field called 'transition_task' to the policy structure, to keep
track of the task which is performing the frequency transition. Using this
field, we make note of this task during _begin() and print a warning if we
find a case where the same task is calling _begin() again, before completing
the previous frequency transition using the corresponding _end().
We have left out ASYNC_NOTIFICATION drivers from this debug infrastructure
for 2 reasons:
1. At the moment, we have no way to avoid a particular scenario where this
debug infrastructure can emit false-positive warnings for such drivers.
The scenario is depicted below:
Task A Task B
/* 1st freq transition */
Invoke _begin() {
...
...
}
Change the frequency
/* 2nd freq transition */
Invoke _begin() {
... //waiting for B to
... //finish _end() for
... //the 1st transition
... | Got interrupt for successful
... | change of frequency (1st one).
... |
... | /* 1st freq transition */
... | Invoke _end() {
... | ...
... V }
...
...
}
This scenario is actually deadlock-free because, once Task A changes the
frequency, it is Task B's responsibility to invoke the corresponding
_end() for the 1st frequency transition. Hence it is perfectly legal for
Task A to go ahead and attempt another frequency transition in the meantime.
(Of course it won't be able to proceed until Task B finishes the 1st _end(),
but this doesn't cause a deadlock or a hang).
The debug infrastructure cannot handle this scenario and will treat it as
a deadlock and print a warning. To avoid this, we exclude such drivers
from the purview of this code.
2. Luckily, we don't _need_ this infrastructure for ASYNC_NOTIFICATION drivers
at all! The cpufreq core does not automatically invoke the _begin() and
_end() APIs during frequency transitions in such drivers. Thus, the driver
alone is responsible for invoking _begin()/_end() and hence there shouldn't
be any conflicts which lead to double invocations. So, we can skip these
drivers, since the probability that such drivers will hit this problem is
extremely low, as outlined above.
Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2014-05-05 12:52:39 +05:30
|
|
|
|
cpufreq: Make sure frequency transitions are serialized
Whenever we change the frequency of a CPU, we call the PRECHANGE and POSTCHANGE
notifiers. They must be serialized, i.e. PRECHANGE and POSTCHANGE notifiers
should strictly alternate, thereby preventing two different sets of PRECHANGE or
POSTCHANGE notifiers from interleaving arbitrarily.
The following examples illustrate why this is important:
Scenario 1:
-----------
A thread reading the value of cpuinfo_cur_freq, will call
__cpufreq_cpu_get()->cpufreq_out_of_sync()->cpufreq_notify_transition()
The ondemand governor can decide to change the frequency of the CPU at the same
time and hence it can end up sending the notifications via ->target().
If the notifiers are not serialized, the following sequence can occur:
- PRECHANGE Notification for freq A (from cpuinfo_cur_freq)
- PRECHANGE Notification for freq B (from target())
- Freq changed by target() to B
- POSTCHANGE Notification for freq B
- POSTCHANGE Notification for freq A
We can see from the above that the last POSTCHANGE Notification happens for freq
A but the hardware is set to run at freq B.
Where would we break then?: adjust_jiffies() in cpufreq.c & cpufreq_callback()
in arch/arm/kernel/smp.c (which also adjusts the jiffies). All the
loops_per_jiffy calculations will get messed up.
Scenario 2:
-----------
The governor calls __cpufreq_driver_target() to change the frequency. At the
same time, if we change scaling_{min|max}_freq from sysfs, it will end up
calling the governor's CPUFREQ_GOV_LIMITS notification, which will also call
__cpufreq_driver_target(). And hence we end up issuing concurrent calls to
->target().
Typically, platforms have the following logic in their ->target() routines:
(Eg: cpufreq-cpu0, omap, exynos, etc)
A. If new freq is more than old: Increase voltage
B. Change freq
C. If new freq is less than old: decrease voltage
Now, if the two concurrent calls to ->target() are X and Y, where X is trying to
increase the freq and Y is trying to decrease it, we get the following race
condition:
X.A: voltage gets increased for larger freq
Y.A: nothing happens
Y.B: freq gets decreased
Y.C: voltage gets decreased
X.B: freq gets increased
X.C: nothing happens
Thus we can end up setting a freq which is not supported by the voltage we have
set. That will probably make the clock to the CPU unstable and the system might
not work properly anymore.
This patch introduces a set of synchronization primitives to serialize frequency
transitions, which are to be used as shown below:
cpufreq_freq_transition_begin();
//Perform the frequency change
cpufreq_freq_transition_end();
The _begin() call sends the PRECHANGE notification whereas the _end() call sends
the POSTCHANGE notification. Also, all the necessary synchronization is handled
within these calls. In particular, even drivers which set the ASYNC_NOTIFICATION
flag can also use these APIs for performing frequency transitions (ie., you can
call _begin() from one task, and call the corresponding _end() from a different
task).
The actual synchronization underneath is not that complicated:
The key challenge is to allow drivers to begin the transition from one thread
and end it in a completely different thread (this is to enable drivers that do
asynchronous POSTCHANGE notification from bottom-halves, to also use the same
interface).
To achieve this, a 'transition_ongoing' flag, a 'transition_lock' spinlock and a
wait-queue are added per-policy. The flag and the wait-queue are used in
conjunction to create an "uninterrupted flow" from _begin() to _end(). The
spinlock is used to ensure that only one such "flow" is in flight at any given
time. Put together, this provides us all the necessary synchronization.
Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2014-03-24 13:35:44 +05:30
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2016-03-30 03:47:49 +02:00
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2016-04-07 23:38:46 +02:00
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2016-03-30 03:47:49 +02:00
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2016-04-07 23:38:46 +02:00
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2005-04-16 15:20:36 -07:00
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2016-07-13 13:25:25 -07:00
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2016-07-21 14:39:26 -07:00
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2016-07-13 13:25:25 -07:00
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2016-07-21 14:39:26 -07:00
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2016-07-13 13:25:25 -07:00
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2016-07-21 19:24:38 -07:00
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2016-07-13 13:25:25 -07:00
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2017-07-19 15:42:42 +05:30
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2017-08-17 09:12:27 +05:30
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2017-07-19 15:42:42 +05:30
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2005-04-16 15:20:36 -07:00
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2014-02-26 22:12:42 +05:30
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2013-12-20 15:24:49 +01:00
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2014-03-11 10:03:00 -07:00
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2013-12-20 15:24:49 +01:00
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2014-03-11 10:03:00 -07:00
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2013-12-20 15:24:49 +01:00
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2005-04-16 15:20:36 -07:00
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2015-01-02 12:34:26 +05:30
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2006-07-06 12:30:26 -07:00
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2015-01-27 14:06:09 +05:30
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2014-09-29 15:50:11 +02:00
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2006-07-06 12:30:26 -07:00
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2005-04-16 15:20:36 -07:00
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2008-03-05 14:28:32 -05:00
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2005-04-16 15:20:36 -07:00
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2006-07-06 12:30:26 -07:00
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2013-04-29 00:08:16 +02:00
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2014-09-29 15:50:11 +02:00
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2005-04-16 15:20:36 -07:00
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2006-07-06 12:30:26 -07:00
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2014-09-29 15:50:11 +02:00
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2006-10-26 16:20:58 +05:30
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2005-04-16 15:20:36 -07:00
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2006-07-06 12:30:26 -07:00
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2005-04-16 15:20:36 -07:00
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2015-01-02 12:34:27 +05:30
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2005-04-16 15:20:36 -07:00
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2006-07-06 12:30:26 -07:00
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2006-01-13 15:54:22 -08:00
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2006-07-06 12:30:26 -07:00
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2015-01-02 12:34:26 +05:30
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2006-07-06 12:30:26 -07:00
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2006-07-06 12:32:01 -07:00
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2011-05-04 08:38:56 -07:00
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2006-07-06 12:32:01 -07:00
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2011-05-04 08:38:56 -07:00
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2006-07-06 12:32:01 -07:00
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2011-05-04 08:38:56 -07:00
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2015-01-02 12:34:26 +05:30
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2006-07-06 12:32:01 -07:00
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2006-07-06 12:30:26 -07:00
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2005-04-16 15:20:36 -07:00
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2006-07-06 12:30:26 -07:00
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2006-01-13 15:54:22 -08:00
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2005-04-16 15:20:36 -07:00
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2006-07-06 12:30:26 -07:00
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2005-04-16 15:20:36 -07:00
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2006-10-26 16:20:58 +05:30
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2005-04-16 15:20:36 -07:00
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2006-02-28 00:43:23 -05:00
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2008-03-05 14:28:32 -05:00
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2006-02-28 00:43:23 -05:00
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2009-01-18 01:37:11 -05:00
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2005-04-16 15:20:36 -07:00
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2009-02-04 01:17:41 +01:00
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2005-04-16 15:20:36 -07:00
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2014-10-13 08:37:40 -07:00
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2017-06-23 22:11:52 -07:00
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2015-01-02 12:34:24 +05:30
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2014-10-13 08:37:40 -07:00
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2017-06-23 22:11:52 -07:00
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2014-10-13 08:37:40 -07:00
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2017-06-23 22:11:52 -07:00
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2014-10-13 08:37:40 -07:00
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2005-04-16 15:20:36 -07:00
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2013-10-02 14:13:16 +05:30
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2013-08-06 22:53:05 +05:30
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2006-04-13 15:14:04 +02:00
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2005-04-16 15:20:36 -07:00
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2008-03-05 14:28:32 -05:00
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2005-04-16 15:20:36 -07:00
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2014-11-10 14:14:50 +08:00
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2005-04-16 15:20:36 -07:00
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2015-08-03 08:36:15 +05:30
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2005-04-16 15:20:36 -07:00
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2009-01-18 01:37:11 -05:00
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2005-04-16 15:20:36 -07:00
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2014-11-10 14:14:50 +08:00
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2013-10-02 14:13:16 +05:30
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2014-11-10 14:14:50 +08:00
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2005-04-16 15:20:36 -07:00
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2009-01-18 01:37:11 -05:00
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2005-04-16 15:20:36 -07:00
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2008-03-05 14:28:32 -05:00
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2005-04-16 15:20:36 -07:00
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2015-01-02 12:34:29 +05:30
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2017-03-15 00:12:16 +01:00
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2005-04-16 15:20:36 -07:00
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2008-03-05 14:28:32 -05:00
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2005-04-16 15:20:36 -07:00
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2009-01-18 01:37:11 -05:00
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2005-04-16 15:20:36 -07:00
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2012-10-23 01:23:43 +02:00
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2009-01-18 01:37:11 -05:00
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2005-04-16 15:20:36 -07:00
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2008-03-05 14:28:32 -05:00
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2005-04-16 15:20:36 -07:00
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2013-09-07 01:24:06 +05:30
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2005-04-16 15:20:36 -07:00
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2015-08-03 08:36:15 +05:30
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2005-04-16 15:20:36 -07:00
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2009-01-18 01:37:11 -05:00
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2005-04-16 15:20:36 -07:00
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2006-10-26 16:20:58 +05:30
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2005-04-16 15:20:36 -07:00
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2013-10-02 14:13:16 +05:30
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2015-08-03 08:36:18 +05:30
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2005-04-16 15:20:36 -07:00
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2008-03-05 14:28:32 -05:00
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2005-04-16 15:20:36 -07:00
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2013-04-29 00:08:16 +02:00
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2005-04-16 15:20:36 -07:00
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2008-03-05 14:28:32 -05:00
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2005-04-16 15:20:36 -07:00
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2013-10-25 19:45:48 +05:30
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2005-04-16 15:20:36 -07:00
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2015-01-27 14:06:09 +05:30
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2009-01-18 01:37:11 -05:00
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2005-04-16 15:20:36 -07:00
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2012-10-23 01:23:43 +02:00
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2005-04-16 15:20:36 -07:00
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2006-02-02 17:03:42 -05:00
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2005-04-16 15:20:36 -07:00
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2008-04-18 13:31:12 -07:00
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2013-06-27 15:08:54 +08:00
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2005-04-16 15:20:36 -07:00
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2009-01-04 05:18:06 -08:00
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2005-04-16 15:20:36 -07:00
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2009-01-18 01:37:11 -05:00
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2005-04-16 15:20:36 -07:00
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2013-06-27 15:08:54 +08:00
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2005-04-16 15:20:36 -07:00
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2008-04-18 13:31:12 -07:00
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2013-06-27 15:08:54 +08:00
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2008-04-18 13:31:12 -07:00
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2013-06-27 15:08:54 +08:00
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2008-04-18 13:31:12 -07:00
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2007-10-26 10:18:21 -07:00
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2008-03-05 14:28:32 -05:00
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2007-10-26 10:18:21 -07:00
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2008-06-05 22:46:33 -07:00
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2007-10-26 10:18:21 -07:00
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2008-06-05 22:46:33 -07:00
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2007-10-26 10:18:21 -07:00
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2005-04-16 15:20:36 -07:00
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2009-11-19 12:31:01 +01:00
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2012-10-23 01:23:33 +02:00
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2009-11-19 12:31:01 +01:00
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2013-04-29 00:08:16 +02:00
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2009-11-19 12:31:01 +01:00
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2010-03-31 21:56:46 +02:00
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2005-04-16 15:20:36 -07:00
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2008-03-05 14:28:32 -05:00
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2005-04-16 15:20:36 -07:00
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2009-02-04 01:17:41 +01:00
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2005-04-16 15:20:36 -07:00
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2008-04-18 13:31:12 -07:00
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2005-04-16 15:20:36 -07:00
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2007-10-26 10:18:21 -07:00
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2005-04-16 15:20:36 -07:00
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2009-01-18 01:37:11 -05:00
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2005-04-16 15:20:36 -07:00
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2009-01-18 01:37:11 -05:00
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2005-04-16 15:20:36 -07:00
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2008-03-05 14:28:32 -05:00
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2013-10-02 14:13:09 +05:30
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2013-08-06 22:53:11 +05:30
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2013-10-18 19:10:15 +05:30
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2016-02-12 23:56:21 +01:00
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2013-10-18 19:10:15 +05:30
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2013-10-02 14:13:09 +05:30
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2005-04-16 15:20:36 -07:00
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2008-03-05 14:28:32 -05:00
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2005-04-16 15:20:36 -07:00
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2008-03-05 14:28:32 -05:00
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2008-03-05 14:22:25 -05:00
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2013-08-06 22:53:11 +05:30
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2017-05-24 10:15:20 +02:00
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2013-09-07 01:23:43 +05:30
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2016-02-12 23:56:21 +01:00
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2006-10-26 16:20:58 +05:30
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2016-02-12 23:56:21 +01:00
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2006-10-26 16:20:58 +05:30
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2017-05-24 10:15:20 +02:00
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2013-09-07 01:23:43 +05:30
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2005-04-16 15:20:36 -07:00
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2008-03-05 14:28:32 -05:00
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2005-04-16 15:20:36 -07:00
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2008-03-05 14:28:32 -05:00
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2011-03-27 15:04:46 +02:00
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2005-04-16 15:20:36 -07:00
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2010-01-19 02:58:23 +01:00
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2005-04-16 15:20:36 -07:00
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2017-03-27 19:33:09 +02:00
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2015-06-10 02:13:21 +02:00
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2017-03-27 19:33:09 +02:00
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cpufreq: create link to policy only for registered CPUs
If a cpufreq driver is registered very early in the boot stage (e.g.
registered from postcore_initcall()), then cpufreq core may generate
kernel warnings for it.
In this case, the CPUs are brought online, then the cpufreq driver is
registered, and then the CPU topology devices are registered. However,
by the time cpufreq_add_dev() gets called, the cpu device isn't stored
in the per-cpu variable (cpu_sys_devices,) which is read by
get_cpu_device().
So the cpufreq core fails to get device for the CPU, for which
cpufreq_add_dev() was called in the first place and we will hit a
WARN_ON(!cpu_dev).
Even if we reuse the 'dev' parameter passed to cpufreq_add_dev() to
avoid that warning, there might be other CPUs online that share the
policy with the cpu for which cpufreq_add_dev() is called. Eventually
get_cpu_device() will return NULL for them as well, and we will hit the
same WARN_ON() again.
In order to fix these issues, change cpufreq core to create links to the
policy for a cpu only when cpufreq_add_dev() is called for that CPU.
Reuse the 'real_cpus' mask to track that as well.
Note that cpufreq_remove_dev() already handles removal of the links for
individual CPUs and cpufreq_add_dev() has aligned with that now.
Reported-by: Russell King <rmk+kernel@arm.linux.org.uk>
Tested-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2016-09-12 12:07:05 +05:30
|
|
|
|
2017-03-27 19:33:09 +02:00
|
|
|
|
|
|
|
|
|
2015-06-10 02:13:21 +02:00
|
|
|
|
|
|
|
|
|
cpufreq: create link to policy only for registered CPUs
If a cpufreq driver is registered very early in the boot stage (e.g.
registered from postcore_initcall()), then cpufreq core may generate
kernel warnings for it.
In this case, the CPUs are brought online, then the cpufreq driver is
registered, and then the CPU topology devices are registered. However,
by the time cpufreq_add_dev() gets called, the cpu device isn't stored
in the per-cpu variable (cpu_sys_devices,) which is read by
get_cpu_device().
So the cpufreq core fails to get device for the CPU, for which
cpufreq_add_dev() was called in the first place and we will hit a
WARN_ON(!cpu_dev).
Even if we reuse the 'dev' parameter passed to cpufreq_add_dev() to
avoid that warning, there might be other CPUs online that share the
policy with the cpu for which cpufreq_add_dev() is called. Eventually
get_cpu_device() will return NULL for them as well, and we will hit the
same WARN_ON() again.
In order to fix these issues, change cpufreq core to create links to the
policy for a cpu only when cpufreq_add_dev() is called for that CPU.
Reuse the 'real_cpus' mask to track that as well.
Note that cpufreq_remove_dev() already handles removal of the links for
individual CPUs and cpufreq_add_dev() has aligned with that now.
Reported-by: Russell King <rmk+kernel@arm.linux.org.uk>
Tested-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2016-09-12 12:07:05 +05:30
|
|
|
|
|
|
|
|
|
2015-06-10 02:13:21 +02:00
|
|
|
|
cpufreq: create link to policy only for registered CPUs
If a cpufreq driver is registered very early in the boot stage (e.g.
registered from postcore_initcall()), then cpufreq core may generate
kernel warnings for it.
In this case, the CPUs are brought online, then the cpufreq driver is
registered, and then the CPU topology devices are registered. However,
by the time cpufreq_add_dev() gets called, the cpu device isn't stored
in the per-cpu variable (cpu_sys_devices,) which is read by
get_cpu_device().
So the cpufreq core fails to get device for the CPU, for which
cpufreq_add_dev() was called in the first place and we will hit a
WARN_ON(!cpu_dev).
Even if we reuse the 'dev' parameter passed to cpufreq_add_dev() to
avoid that warning, there might be other CPUs online that share the
policy with the cpu for which cpufreq_add_dev() is called. Eventually
get_cpu_device() will return NULL for them as well, and we will hit the
same WARN_ON() again.
In order to fix these issues, change cpufreq core to create links to the
policy for a cpu only when cpufreq_add_dev() is called for that CPU.
Reuse the 'real_cpus' mask to track that as well.
Note that cpufreq_remove_dev() already handles removal of the links for
individual CPUs and cpufreq_add_dev() has aligned with that now.
Reported-by: Russell King <rmk+kernel@arm.linux.org.uk>
Tested-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2016-09-12 12:07:05 +05:30
|
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2015-06-10 02:13:21 +02:00
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2015-07-27 23:11:37 +02:00
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2009-07-08 18:05:42 -04:00
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2013-04-29 00:08:16 +02:00
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2015-01-02 12:34:23 +05:30
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2009-07-08 18:05:42 -04:00
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2014-11-24 10:08:03 +01:00
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2009-07-08 18:05:42 -04:00
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2013-04-29 00:08:16 +02:00
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2009-07-08 18:05:42 -04:00
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2014-11-24 10:08:03 +01:00
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2009-07-08 18:05:42 -04:00
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2014-10-13 08:37:40 -07:00
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2014-11-24 10:08:03 +01:00
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2014-10-13 08:37:40 -07:00
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2013-04-29 00:08:16 +02:00
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2009-11-19 12:31:01 +01:00
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2014-11-24 10:08:03 +01:00
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2009-11-19 12:31:01 +01:00
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2009-07-08 18:05:42 -04:00
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cpufreq: create link to policy only for registered CPUs
If a cpufreq driver is registered very early in the boot stage (e.g.
registered from postcore_initcall()), then cpufreq core may generate
kernel warnings for it.
In this case, the CPUs are brought online, then the cpufreq driver is
registered, and then the CPU topology devices are registered. However,
by the time cpufreq_add_dev() gets called, the cpu device isn't stored
in the per-cpu variable (cpu_sys_devices,) which is read by
get_cpu_device().
So the cpufreq core fails to get device for the CPU, for which
cpufreq_add_dev() was called in the first place and we will hit a
WARN_ON(!cpu_dev).
Even if we reuse the 'dev' parameter passed to cpufreq_add_dev() to
avoid that warning, there might be other CPUs online that share the
policy with the cpu for which cpufreq_add_dev() is called. Eventually
get_cpu_device() will return NULL for them as well, and we will hit the
same WARN_ON() again.
In order to fix these issues, change cpufreq core to create links to the
policy for a cpu only when cpufreq_add_dev() is called for that CPU.
Reuse the 'real_cpus' mask to track that as well.
Note that cpufreq_remove_dev() already handles removal of the links for
individual CPUs and cpufreq_add_dev() has aligned with that now.
Reported-by: Russell King <rmk+kernel@arm.linux.org.uk>
Tested-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2016-09-12 12:07:05 +05:30
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2013-07-30 04:24:23 +05:30
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2016-02-05 02:37:42 +01:00
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2015-07-08 15:12:16 +05:30
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2013-07-30 04:24:23 +05:30
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2014-03-04 11:43:59 +08:00
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2013-07-30 04:24:23 +05:30
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2013-08-06 22:53:06 +05:30
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2013-12-19 22:50:50 +00:00
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2014-03-04 11:43:59 +08:00
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2015-05-12 12:22:34 +05:30
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2016-02-05 02:37:42 +01:00
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2014-03-04 11:43:59 +08:00
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2016-02-05 02:37:42 +01:00
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2014-03-04 11:43:59 +08:00
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2015-12-01 16:52:14 -08:00
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2009-07-08 18:48:47 -04:00
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2015-07-08 15:12:16 +05:30
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2009-07-08 18:05:42 -04:00
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2015-07-27 23:11:37 +02:00
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2013-01-29 14:39:08 +00:00
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2013-10-25 19:45:48 +05:30
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2013-01-29 14:39:08 +00:00
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2015-02-19 17:02:06 +05:30
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2016-02-11 17:31:12 +05:30
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2016-05-12 15:14:12 +02:00
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2013-01-29 14:39:08 +00:00
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2013-02-07 10:55:00 +05:30
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2013-10-25 19:45:48 +05:30
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2016-03-21 15:45:24 +01:00
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2016-02-11 17:31:12 +05:30
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2013-08-06 22:53:13 +05:30
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2013-04-22 00:48:03 +02:00
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2016-02-11 17:31:12 +05:30
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2013-01-29 14:39:08 +00:00
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2005-04-16 15:20:36 -07:00
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2016-02-22 16:36:42 +05:30
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2013-01-29 14:39:08 +00:00
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2005-04-16 15:20:36 -07:00
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2015-07-27 23:11:50 +02:00
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2013-07-30 04:24:11 +05:30
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2016-03-03 14:51:33 +05:30
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2013-07-30 04:24:11 +05:30
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cpufreq: Avoid attempts to create duplicate symbolic links
After commit 87549141d516 (cpufreq: Stop migrating sysfs files on
hotplug) there is a problem with CPUs that share cpufreq policy
objects with other CPUs and are initially offline.
Say CPU1 shares a policy with CPU0 which is online and is registered
first. As part of the registration process, cpufreq_add_dev() is
called for it. It creates the policy object and a symbolic link
to it from the CPU1's sysfs directory. If CPU1 is registered
subsequently and it is offline at that time, cpufreq_add_dev() will
attempt to create a symbolic link to the policy object for it, but
that link is present already, so a warning about that will be
triggered.
To avoid that warning, make cpufreq use an additional CPU mask
containing related CPUs that are actually present for each policy
object. That mask is initialized when the policy object is populated
after its creation (for the first online CPU using it) and it includes
CPUs from the "policy CPUs" mask returned by the cpufreq driver's
->init() callback that are physically present at that time. Symbolic
links to the policy are created only for the CPUs in that mask.
If cpufreq_add_dev() is invoked for an offline CPU, it checks the
new mask and only creates the symlink if the CPU was not in it (the
CPU is added to the mask at the same time).
In turn, cpufreq_remove_dev() drops the given CPU from the new mask,
removes its symlink to the policy object and returns, unless it is
the CPU owning the policy object. In that case, the policy object
is moved to a new CPU's sysfs directory or deleted if the CPU being
removed was the last user of the policy.
While at it, notice that cpufreq_remove_dev() can't fail, because
its return value is ignored, so make it ignore return values from
__cpufreq_remove_dev_prepare() and __cpufreq_remove_dev_finish()
and prevent these functions from aborting on errors returned by
__cpufreq_governor(). Also drop the now unused sif argument from
them.
Fixes: 87549141d516 (cpufreq: Stop migrating sysfs files on hotplug)
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reported-and-tested-by: Russell King <linux@arm.linux.org.uk>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
2015-07-26 02:07:47 +02:00
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2016-03-03 14:51:33 +05:30
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2013-08-06 22:53:08 +05:30
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2013-10-18 19:10:15 +05:30
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cpufreq: Make sure frequency transitions are serialized
Whenever we change the frequency of a CPU, we call the PRECHANGE and POSTCHANGE
notifiers. They must be serialized, i.e. PRECHANGE and POSTCHANGE notifiers
should strictly alternate, thereby preventing two different sets of PRECHANGE or
POSTCHANGE notifiers from interleaving arbitrarily.
The following examples illustrate why this is important:
Scenario 1:
-----------
A thread reading the value of cpuinfo_cur_freq, will call
__cpufreq_cpu_get()->cpufreq_out_of_sync()->cpufreq_notify_transition()
The ondemand governor can decide to change the frequency of the CPU at the same
time and hence it can end up sending the notifications via ->target().
If the notifiers are not serialized, the following sequence can occur:
- PRECHANGE Notification for freq A (from cpuinfo_cur_freq)
- PRECHANGE Notification for freq B (from target())
- Freq changed by target() to B
- POSTCHANGE Notification for freq B
- POSTCHANGE Notification for freq A
We can see from the above that the last POSTCHANGE Notification happens for freq
A but the hardware is set to run at freq B.
Where would we break then?: adjust_jiffies() in cpufreq.c & cpufreq_callback()
in arch/arm/kernel/smp.c (which also adjusts the jiffies). All the
loops_per_jiffy calculations will get messed up.
Scenario 2:
-----------
The governor calls __cpufreq_driver_target() to change the frequency. At the
same time, if we change scaling_{min|max}_freq from sysfs, it will end up
calling the governor's CPUFREQ_GOV_LIMITS notification, which will also call
__cpufreq_driver_target(). And hence we end up issuing concurrent calls to
->target().
Typically, platforms have the following logic in their ->target() routines:
(Eg: cpufreq-cpu0, omap, exynos, etc)
A. If new freq is more than old: Increase voltage
B. Change freq
C. If new freq is less than old: decrease voltage
Now, if the two concurrent calls to ->target() are X and Y, where X is trying to
increase the freq and Y is trying to decrease it, we get the following race
condition:
X.A: voltage gets increased for larger freq
Y.A: nothing happens
Y.B: freq gets decreased
Y.C: voltage gets decreased
X.B: freq gets increased
X.C: nothing happens
Thus we can end up setting a freq which is not supported by the voltage we have
set. That will probably make the clock to the CPU unstable and the system might
not work properly anymore.
This patch introduces a set of synchronization primitives to serialize frequency
transitions, which are to be used as shown below:
cpufreq_freq_transition_begin();
//Perform the frequency change
cpufreq_freq_transition_end();
The _begin() call sends the PRECHANGE notification whereas the _end() call sends
the POSTCHANGE notification. Also, all the necessary synchronization is handled
within these calls. In particular, even drivers which set the ASYNC_NOTIFICATION
flag can also use these APIs for performing frequency transitions (ie., you can
call _begin() from one task, and call the corresponding _end() from a different
task).
The actual synchronization underneath is not that complicated:
The key challenge is to allow drivers to begin the transition from one thread
and end it in a completely different thread (this is to enable drivers that do
asynchronous POSTCHANGE notification from bottom-halves, to also use the same
interface).
To achieve this, a 'transition_ongoing' flag, a 'transition_lock' spinlock and a
wait-queue are added per-policy. The flag and the wait-queue are used in
conjunction to create an "uninterrupted flow" from _begin() to _end(). The
spinlock is used to ensure that only one such "flow" is in flight at any given
time. Put together, this provides us all the necessary synchronization.
Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2014-03-24 13:35:44 +05:30
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2015-01-02 12:34:38 +05:30
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2013-10-18 19:10:15 +05:30
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2015-07-27 23:11:50 +02:00
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2013-07-30 04:24:11 +05:30
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2016-03-03 14:51:33 +05:30
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2015-06-08 18:25:29 +05:30
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2013-07-30 04:24:11 +05:30
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2017-01-05 10:17:27 +05:30
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2013-12-20 21:26:02 +05:30
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2015-06-10 02:13:21 +02:00
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2016-05-31 22:14:44 +02:00
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2013-12-20 21:26:02 +05:30
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2015-06-10 02:13:21 +02:00
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2013-12-20 21:26:02 +05:30
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2017-01-05 10:17:27 +05:30
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2013-07-30 04:24:11 +05:30
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2015-05-08 11:53:45 +05:30
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2017-01-05 10:17:27 +05:30
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cpufreq: Avoid attempts to create duplicate symbolic links
After commit 87549141d516 (cpufreq: Stop migrating sysfs files on
hotplug) there is a problem with CPUs that share cpufreq policy
objects with other CPUs and are initially offline.
Say CPU1 shares a policy with CPU0 which is online and is registered
first. As part of the registration process, cpufreq_add_dev() is
called for it. It creates the policy object and a symbolic link
to it from the CPU1's sysfs directory. If CPU1 is registered
subsequently and it is offline at that time, cpufreq_add_dev() will
attempt to create a symbolic link to the policy object for it, but
that link is present already, so a warning about that will be
triggered.
To avoid that warning, make cpufreq use an additional CPU mask
containing related CPUs that are actually present for each policy
object. That mask is initialized when the policy object is populated
after its creation (for the first online CPU using it) and it includes
CPUs from the "policy CPUs" mask returned by the cpufreq driver's
->init() callback that are physically present at that time. Symbolic
links to the policy are created only for the CPUs in that mask.
If cpufreq_add_dev() is invoked for an offline CPU, it checks the
new mask and only creates the symlink if the CPU was not in it (the
CPU is added to the mask at the same time).
In turn, cpufreq_remove_dev() drops the given CPU from the new mask,
removes its symlink to the policy object and returns, unless it is
the CPU owning the policy object. In that case, the policy object
is moved to a new CPU's sysfs directory or deleted if the CPU being
removed was the last user of the policy.
While at it, notice that cpufreq_remove_dev() can't fail, because
its return value is ignored, so make it ignore return values from
__cpufreq_remove_dev_prepare() and __cpufreq_remove_dev_finish()
and prevent these functions from aborting on errors returned by
__cpufreq_governor(). Also drop the now unused sif argument from
them.
Fixes: 87549141d516 (cpufreq: Stop migrating sysfs files on hotplug)
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reported-and-tested-by: Russell King <linux@arm.linux.org.uk>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
2015-07-26 02:07:47 +02:00
|
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|
2013-07-30 04:24:11 +05:30
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2015-07-29 03:03:44 +02:00
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2005-04-16 15:20:36 -07:00
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2015-01-02 12:34:32 +05:30
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2015-07-29 03:08:57 +02:00
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2005-04-16 15:20:36 -07:00
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2015-07-29 03:03:44 +02:00
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2005-10-30 14:59:54 -08:00
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2015-07-29 03:03:44 +02:00
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2013-08-06 22:53:11 +05:30
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2015-02-19 17:02:06 +05:30
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2015-05-12 12:22:12 +05:30
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2015-07-27 23:11:21 +02:00
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2015-05-12 12:22:12 +05:30
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2015-07-27 23:11:21 +02:00
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2015-07-27 23:11:37 +02:00
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2005-04-16 15:20:36 -07:00
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2015-07-27 23:11:21 +02:00
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2015-07-29 03:08:57 +02:00
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2015-07-27 23:11:21 +02:00
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2015-07-29 03:08:57 +02:00
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2015-07-27 23:11:50 +02:00
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2013-12-27 01:07:11 +01:00
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2015-07-27 23:11:30 +02:00
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2013-12-27 01:07:11 +01:00
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cpufreq: Fix crash in cpufreq-stats during suspend/resume
Stephen Warren reported that the cpufreq-stats code hits a NULL pointer
dereference during the second attempt to suspend a system. He also
pin-pointed the problem to commit 5302c3f "cpufreq: Perform light-weight
init/teardown during suspend/resume".
That commit actually ensured that the cpufreq-stats table and the
cpufreq-stats sysfs entries are *not* torn down (ie., not freed) during
suspend/resume, which makes it all the more surprising. However, it turns
out that the root-cause is not that we access an already freed memory, but
that the reference to the allocated memory gets moved around and we lose
track of that during resume, leading to the reported crash in a subsequent
suspend attempt.
In the suspend path, during CPU offline, the value of policy->cpu is updated
by choosing one of the surviving CPUs in that policy, as long as there is
atleast one CPU in that policy. And cpufreq_stats_update_policy_cpu() is
invoked to update the reference to the stats structure by assigning it to
the new CPU. However, in the resume path, during CPU online, we end up
assigning a fresh CPU as the policy->cpu, without letting cpufreq-stats
know about this. Thus the reference to the stats structure remains
(incorrectly) associated with the old CPU. So, in a subsequent suspend attempt,
during CPU offline, we end up accessing an incorrect location to get the
stats structure, which eventually leads to the NULL pointer dereference.
Fix this by letting cpufreq-stats know about the update of the policy->cpu
during CPU online in the resume path. (Also, move the update_policy_cpu()
function higher up in the file, so that __cpufreq_add_dev() can invoke
it).
Reported-and-tested-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2013-09-12 01:42:59 +05:30
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2009-01-04 05:18:06 -08:00
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2005-04-16 15:20:36 -07:00
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2013-04-29 00:08:16 +02:00
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2005-04-16 15:20:36 -07:00
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2011-03-27 15:04:46 +02:00
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2015-07-08 15:12:15 +05:30
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2005-04-16 15:20:36 -07:00
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2013-01-12 05:14:38 +00:00
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2014-11-24 10:08:03 +01:00
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2015-07-29 03:08:57 +02:00
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2015-07-27 23:11:44 +02:00
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2015-10-15 21:35:21 +05:30
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2015-07-27 23:11:44 +02:00
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cpufreq: Avoid attempts to create duplicate symbolic links
After commit 87549141d516 (cpufreq: Stop migrating sysfs files on
hotplug) there is a problem with CPUs that share cpufreq policy
objects with other CPUs and are initially offline.
Say CPU1 shares a policy with CPU0 which is online and is registered
first. As part of the registration process, cpufreq_add_dev() is
called for it. It creates the policy object and a symbolic link
to it from the CPU1's sysfs directory. If CPU1 is registered
subsequently and it is offline at that time, cpufreq_add_dev() will
attempt to create a symbolic link to the policy object for it, but
that link is present already, so a warning about that will be
triggered.
To avoid that warning, make cpufreq use an additional CPU mask
containing related CPUs that are actually present for each policy
object. That mask is initialized when the policy object is populated
after its creation (for the first online CPU using it) and it includes
CPUs from the "policy CPUs" mask returned by the cpufreq driver's
->init() callback that are physically present at that time. Symbolic
links to the policy are created only for the CPUs in that mask.
If cpufreq_add_dev() is invoked for an offline CPU, it checks the
new mask and only creates the symlink if the CPU was not in it (the
CPU is added to the mask at the same time).
In turn, cpufreq_remove_dev() drops the given CPU from the new mask,
removes its symlink to the policy object and returns, unless it is
the CPU owning the policy object. In that case, the policy object
is moved to a new CPU's sysfs directory or deleted if the CPU being
removed was the last user of the policy.
While at it, notice that cpufreq_remove_dev() can't fail, because
its return value is ignored, so make it ignore return values from
__cpufreq_remove_dev_prepare() and __cpufreq_remove_dev_finish()
and prevent these functions from aborting on errors returned by
__cpufreq_governor(). Also drop the now unused sif argument from
them.
Fixes: 87549141d516 (cpufreq: Stop migrating sysfs files on hotplug)
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reported-and-tested-by: Russell King <linux@arm.linux.org.uk>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
2015-07-26 02:07:47 +02:00
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2014-03-04 11:44:00 +08:00
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2015-07-29 03:08:57 +02:00
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2014-03-04 11:44:00 +08:00
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2014-11-24 10:08:03 +01:00
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2017-03-27 19:33:09 +02:00
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2015-05-08 11:53:45 +05:30
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2017-03-27 19:33:09 +02:00
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2017-03-21 11:36:06 +05:30
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2015-05-08 11:53:45 +05:30
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2014-01-09 20:38:43 +05:30
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2014-03-12 21:49:33 +01:00
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2013-10-03 20:28:30 +05:30
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2015-07-08 15:12:15 +05:30
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2013-10-03 20:28:30 +05:30
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2013-12-03 11:20:46 +05:30
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2015-07-29 03:08:57 +02:00
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2015-07-27 23:11:37 +02:00
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2013-07-30 04:24:49 +05:30
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2015-07-08 15:12:15 +05:30
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2016-05-31 22:14:44 +02:00
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2006-03-05 03:37:23 -05:00
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2015-05-08 11:53:45 +05:30
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2013-08-20 12:08:23 +05:30
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2015-07-08 15:12:16 +05:30
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2015-07-29 03:08:57 +02:00
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2013-12-24 07:11:01 +05:30
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2013-07-30 04:24:23 +05:30
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2014-03-04 11:44:01 +08:00
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2013-12-24 07:11:01 +05:30
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2007-12-17 15:54:39 -04:00
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2014-11-27 06:07:51 +05:30
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2011-03-27 15:04:46 +02:00
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2006-03-29 01:48:37 -05:00
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2005-04-16 15:20:36 -07:00
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2015-07-08 15:12:15 +05:30
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2014-09-10 10:12:08 -04:00
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2013-10-03 20:28:30 +05:30
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2017-03-27 19:33:09 +02:00
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2015-07-08 15:12:15 +05:30
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2017-01-05 10:17:27 +05:30
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2005-04-16 15:20:36 -07:00
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2015-07-29 03:03:44 +02:00
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2016-04-07 03:31:57 +02:00
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2015-07-29 03:03:44 +02:00
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cpufreq: create link to policy only for registered CPUs
If a cpufreq driver is registered very early in the boot stage (e.g.
registered from postcore_initcall()), then cpufreq core may generate
kernel warnings for it.
In this case, the CPUs are brought online, then the cpufreq driver is
registered, and then the CPU topology devices are registered. However,
by the time cpufreq_add_dev() gets called, the cpu device isn't stored
in the per-cpu variable (cpu_sys_devices,) which is read by
get_cpu_device().
So the cpufreq core fails to get device for the CPU, for which
cpufreq_add_dev() was called in the first place and we will hit a
WARN_ON(!cpu_dev).
Even if we reuse the 'dev' parameter passed to cpufreq_add_dev() to
avoid that warning, there might be other CPUs online that share the
policy with the cpu for which cpufreq_add_dev() is called. Eventually
get_cpu_device() will return NULL for them as well, and we will hit the
same WARN_ON() again.
In order to fix these issues, change cpufreq core to create links to the
policy for a cpu only when cpufreq_add_dev() is called for that CPU.
Reuse the 'real_cpus' mask to track that as well.
Note that cpufreq_remove_dev() already handles removal of the links for
individual CPUs and cpufreq_add_dev() has aligned with that now.
Reported-by: Russell King <rmk+kernel@arm.linux.org.uk>
Tested-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2016-09-12 12:07:05 +05:30
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2015-07-29 03:03:44 +02:00
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cpufreq: create link to policy only for registered CPUs
If a cpufreq driver is registered very early in the boot stage (e.g.
registered from postcore_initcall()), then cpufreq core may generate
kernel warnings for it.
In this case, the CPUs are brought online, then the cpufreq driver is
registered, and then the CPU topology devices are registered. However,
by the time cpufreq_add_dev() gets called, the cpu device isn't stored
in the per-cpu variable (cpu_sys_devices,) which is read by
get_cpu_device().
So the cpufreq core fails to get device for the CPU, for which
cpufreq_add_dev() was called in the first place and we will hit a
WARN_ON(!cpu_dev).
Even if we reuse the 'dev' parameter passed to cpufreq_add_dev() to
avoid that warning, there might be other CPUs online that share the
policy with the cpu for which cpufreq_add_dev() is called. Eventually
get_cpu_device() will return NULL for them as well, and we will hit the
same WARN_ON() again.
In order to fix these issues, change cpufreq core to create links to the
policy for a cpu only when cpufreq_add_dev() is called for that CPU.
Reuse the 'real_cpus' mask to track that as well.
Note that cpufreq_remove_dev() already handles removal of the links for
individual CPUs and cpufreq_add_dev() has aligned with that now.
Reported-by: Russell King <rmk+kernel@arm.linux.org.uk>
Tested-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2016-09-12 12:07:05 +05:30
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2015-07-29 03:03:44 +02:00
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|
|
cpufreq: create link to policy only for registered CPUs
If a cpufreq driver is registered very early in the boot stage (e.g.
registered from postcore_initcall()), then cpufreq core may generate
kernel warnings for it.
In this case, the CPUs are brought online, then the cpufreq driver is
registered, and then the CPU topology devices are registered. However,
by the time cpufreq_add_dev() gets called, the cpu device isn't stored
in the per-cpu variable (cpu_sys_devices,) which is read by
get_cpu_device().
So the cpufreq core fails to get device for the CPU, for which
cpufreq_add_dev() was called in the first place and we will hit a
WARN_ON(!cpu_dev).
Even if we reuse the 'dev' parameter passed to cpufreq_add_dev() to
avoid that warning, there might be other CPUs online that share the
policy with the cpu for which cpufreq_add_dev() is called. Eventually
get_cpu_device() will return NULL for them as well, and we will hit the
same WARN_ON() again.
In order to fix these issues, change cpufreq core to create links to the
policy for a cpu only when cpufreq_add_dev() is called for that CPU.
Reuse the 'real_cpus' mask to track that as well.
Note that cpufreq_remove_dev() already handles removal of the links for
individual CPUs and cpufreq_add_dev() has aligned with that now.
Reported-by: Russell King <rmk+kernel@arm.linux.org.uk>
Tested-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2016-09-12 12:07:05 +05:30
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2016-04-07 03:31:57 +02:00
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2017-03-27 19:33:09 +02:00
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2013-08-06 22:53:11 +05:30
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2017-03-27 19:33:09 +02:00
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2005-04-16 15:20:36 -07:00
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2016-09-06 19:04:48 +02:00
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2005-04-16 15:20:36 -07:00
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2013-08-06 22:53:05 +05:30
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2016-02-11 17:31:11 +05:30
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2005-04-16 15:20:36 -07:00
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2013-01-14 13:23:03 +00:00
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2005-04-16 15:20:36 -07:00
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2015-05-08 11:53:45 +05:30
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2013-08-06 22:53:05 +05:30
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2013-01-14 13:23:03 +00:00
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2016-09-06 19:04:48 +02:00
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2005-04-16 15:20:36 -07:00
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2016-02-11 17:31:12 +05:30
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2016-05-12 15:14:12 +02:00
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[CPUFREQ] CPU hotplug, re-create sysfs directory and symlinks
When we discover CPUs that are affected by each other's
frequency/voltage transitions, the first CPU gets a sysfs directory
created, and rest of the siblings get symlinks. Currently, when we
hotplug off only the first CPU, all of the symlinks and the sysfs
directory gets removed. Even though rest of the siblings are still
online and functional, they are orphaned, and no longer governed by
cpufreq.
This patch, given the above scenario, creates a sysfs directory for
the first sibling and symlinks for the rest of the siblings.
Please note the recursive call, it was rather too ugly to roll it
out. And the removal of redundant NULL setting (it is already taken
care of near the top of the function).
Signed-off-by: Jacob Shin <jacob.shin@amd.com>
Acked-by: Mark Langsdorf <mark.langsdorf@amd.com>
Reviewed-by: Thomas Renninger <trenn@suse.de>
Signed-off-by: Dave Jones <davej@redhat.com>
Cc: stable@kernel.org
2011-04-27 13:32:11 -05:00
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2015-06-10 02:20:23 +02:00
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2015-05-12 12:22:34 +05:30
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2015-06-10 02:20:23 +02:00
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2015-12-01 16:52:14 -08:00
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2015-06-10 02:20:23 +02:00
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2005-04-16 15:20:36 -07:00
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2015-06-10 02:20:23 +02:00
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2016-03-21 15:45:24 +01:00
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2015-06-10 02:20:23 +02:00
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2016-02-11 17:31:11 +05:30
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2016-02-11 17:31:12 +05:30
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2016-02-11 17:31:11 +05:30
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2014-03-19 08:45:53 -07:00
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2005-04-16 15:20:36 -07:00
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2016-05-12 15:13:35 +02:00
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2015-06-10 02:13:21 +02:00
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2015-10-07 13:50:44 -07:00
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2015-06-10 02:13:21 +02:00
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2015-10-07 13:50:44 -07:00
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2016-02-11 17:31:12 +05:30
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2016-09-06 19:04:48 +02:00
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2005-04-16 15:20:36 -07:00
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2013-09-07 01:23:09 +05:30
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2013-10-02 14:13:14 +05:30
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2013-09-07 01:23:09 +05:30
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2015-07-30 15:04:01 +05:30
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2007-02-05 16:12:44 -08:00
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2011-12-21 14:29:42 -08:00
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|
cpufreq: Avoid attempts to create duplicate symbolic links
After commit 87549141d516 (cpufreq: Stop migrating sysfs files on
hotplug) there is a problem with CPUs that share cpufreq policy
objects with other CPUs and are initially offline.
Say CPU1 shares a policy with CPU0 which is online and is registered
first. As part of the registration process, cpufreq_add_dev() is
called for it. It creates the policy object and a symbolic link
to it from the CPU1's sysfs directory. If CPU1 is registered
subsequently and it is offline at that time, cpufreq_add_dev() will
attempt to create a symbolic link to the policy object for it, but
that link is present already, so a warning about that will be
triggered.
To avoid that warning, make cpufreq use an additional CPU mask
containing related CPUs that are actually present for each policy
object. That mask is initialized when the policy object is populated
after its creation (for the first online CPU using it) and it includes
CPUs from the "policy CPUs" mask returned by the cpufreq driver's
->init() callback that are physically present at that time. Symbolic
links to the policy are created only for the CPUs in that mask.
If cpufreq_add_dev() is invoked for an offline CPU, it checks the
new mask and only creates the symlink if the CPU was not in it (the
CPU is added to the mask at the same time).
In turn, cpufreq_remove_dev() drops the given CPU from the new mask,
removes its symlink to the policy object and returns, unless it is
the CPU owning the policy object. In that case, the policy object
is moved to a new CPU's sysfs directory or deleted if the CPU being
removed was the last user of the policy.
While at it, notice that cpufreq_remove_dev() can't fail, because
its return value is ignored, so make it ignore return values from
__cpufreq_remove_dev_prepare() and __cpufreq_remove_dev_finish()
and prevent these functions from aborting on errors returned by
__cpufreq_governor(). Also drop the now unused sif argument from
them.
Fixes: 87549141d516 (cpufreq: Stop migrating sysfs files on hotplug)
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reported-and-tested-by: Russell King <linux@arm.linux.org.uk>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
2015-07-26 02:07:47 +02:00
|
|
|
|
2007-03-26 12:03:19 -07:00
|
|
|
|
cpufreq: Avoid attempts to create duplicate symbolic links
After commit 87549141d516 (cpufreq: Stop migrating sysfs files on
hotplug) there is a problem with CPUs that share cpufreq policy
objects with other CPUs and are initially offline.
Say CPU1 shares a policy with CPU0 which is online and is registered
first. As part of the registration process, cpufreq_add_dev() is
called for it. It creates the policy object and a symbolic link
to it from the CPU1's sysfs directory. If CPU1 is registered
subsequently and it is offline at that time, cpufreq_add_dev() will
attempt to create a symbolic link to the policy object for it, but
that link is present already, so a warning about that will be
triggered.
To avoid that warning, make cpufreq use an additional CPU mask
containing related CPUs that are actually present for each policy
object. That mask is initialized when the policy object is populated
after its creation (for the first online CPU using it) and it includes
CPUs from the "policy CPUs" mask returned by the cpufreq driver's
->init() callback that are physically present at that time. Symbolic
links to the policy are created only for the CPUs in that mask.
If cpufreq_add_dev() is invoked for an offline CPU, it checks the
new mask and only creates the symlink if the CPU was not in it (the
CPU is added to the mask at the same time).
In turn, cpufreq_remove_dev() drops the given CPU from the new mask,
removes its symlink to the policy object and returns, unless it is
the CPU owning the policy object. In that case, the policy object
is moved to a new CPU's sysfs directory or deleted if the CPU being
removed was the last user of the policy.
While at it, notice that cpufreq_remove_dev() can't fail, because
its return value is ignored, so make it ignore return values from
__cpufreq_remove_dev_prepare() and __cpufreq_remove_dev_finish()
and prevent these functions from aborting on errors returned by
__cpufreq_governor(). Also drop the now unused sif argument from
them.
Fixes: 87549141d516 (cpufreq: Stop migrating sysfs files on hotplug)
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reported-and-tested-by: Russell King <linux@arm.linux.org.uk>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
2015-07-26 02:07:47 +02:00
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2015-08-31 08:47:40 -07:00
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2015-06-10 02:13:21 +02:00
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2016-02-11 17:31:11 +05:30
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2015-06-10 02:13:21 +02:00
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cpufreq: Avoid attempts to create duplicate symbolic links
After commit 87549141d516 (cpufreq: Stop migrating sysfs files on
hotplug) there is a problem with CPUs that share cpufreq policy
objects with other CPUs and are initially offline.
Say CPU1 shares a policy with CPU0 which is online and is registered
first. As part of the registration process, cpufreq_add_dev() is
called for it. It creates the policy object and a symbolic link
to it from the CPU1's sysfs directory. If CPU1 is registered
subsequently and it is offline at that time, cpufreq_add_dev() will
attempt to create a symbolic link to the policy object for it, but
that link is present already, so a warning about that will be
triggered.
To avoid that warning, make cpufreq use an additional CPU mask
containing related CPUs that are actually present for each policy
object. That mask is initialized when the policy object is populated
after its creation (for the first online CPU using it) and it includes
CPUs from the "policy CPUs" mask returned by the cpufreq driver's
->init() callback that are physically present at that time. Symbolic
links to the policy are created only for the CPUs in that mask.
If cpufreq_add_dev() is invoked for an offline CPU, it checks the
new mask and only creates the symlink if the CPU was not in it (the
CPU is added to the mask at the same time).
In turn, cpufreq_remove_dev() drops the given CPU from the new mask,
removes its symlink to the policy object and returns, unless it is
the CPU owning the policy object. In that case, the policy object
is moved to a new CPU's sysfs directory or deleted if the CPU being
removed was the last user of the policy.
While at it, notice that cpufreq_remove_dev() can't fail, because
its return value is ignored, so make it ignore return values from
__cpufreq_remove_dev_prepare() and __cpufreq_remove_dev_finish()
and prevent these functions from aborting on errors returned by
__cpufreq_governor(). Also drop the now unused sif argument from
them.
Fixes: 87549141d516 (cpufreq: Stop migrating sysfs files on hotplug)
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reported-and-tested-by: Russell King <linux@arm.linux.org.uk>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
2015-07-26 02:07:47 +02:00
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|
cpufreq: create link to policy only for registered CPUs
If a cpufreq driver is registered very early in the boot stage (e.g.
registered from postcore_initcall()), then cpufreq core may generate
kernel warnings for it.
In this case, the CPUs are brought online, then the cpufreq driver is
registered, and then the CPU topology devices are registered. However,
by the time cpufreq_add_dev() gets called, the cpu device isn't stored
in the per-cpu variable (cpu_sys_devices,) which is read by
get_cpu_device().
So the cpufreq core fails to get device for the CPU, for which
cpufreq_add_dev() was called in the first place and we will hit a
WARN_ON(!cpu_dev).
Even if we reuse the 'dev' parameter passed to cpufreq_add_dev() to
avoid that warning, there might be other CPUs online that share the
policy with the cpu for which cpufreq_add_dev() is called. Eventually
get_cpu_device() will return NULL for them as well, and we will hit the
same WARN_ON() again.
In order to fix these issues, change cpufreq core to create links to the
policy for a cpu only when cpufreq_add_dev() is called for that CPU.
Reuse the 'real_cpus' mask to track that as well.
Note that cpufreq_remove_dev() already handles removal of the links for
individual CPUs and cpufreq_add_dev() has aligned with that now.
Reported-by: Russell King <rmk+kernel@arm.linux.org.uk>
Tested-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2016-09-12 12:07:05 +05:30
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2015-11-21 09:06:49 +05:30
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2017-01-05 10:17:27 +05:30
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2007-02-05 16:12:44 -08:00
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2005-04-16 15:20:36 -07:00
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2013-06-19 14:19:33 +05:30
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2015-01-02 12:34:28 +05:30
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2005-04-16 15:20:36 -07:00
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2009-01-18 01:37:11 -05:00
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2005-04-16 15:20:36 -07:00
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2015-01-02 12:34:28 +05:30
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2006-10-26 16:20:58 +05:30
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2005-04-16 15:20:36 -07:00
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2013-03-24 11:56:43 +05:30
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2014-03-11 10:03:00 -07:00
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2015-01-02 12:34:28 +05:30
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2005-04-16 15:20:36 -07:00
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2015-01-02 12:34:28 +05:30
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2005-04-16 15:20:36 -07:00
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2013-03-24 11:56:43 +05:30
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2014-03-24 13:35:45 +05:30
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2005-04-16 15:20:36 -07:00
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2006-02-28 00:43:23 -05:00
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2006-12-13 14:49:15 +05:30
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2005-12-02 10:43:20 -08:00
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2013-02-06 09:02:08 -08:00
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2006-10-26 16:20:58 +05:30
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2016-03-11 09:43:07 +01:00
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2005-12-02 10:43:20 -08:00
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2016-03-11 09:43:07 +01:00
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2013-02-06 09:02:08 -08:00
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2005-12-02 10:43:20 -08:00
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2006-10-26 16:20:58 +05:30
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2005-12-02 10:43:20 -08:00
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2008-02-07 16:33:49 -05:00
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2005-12-02 10:43:20 -08:00
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2011-06-28 10:59:12 -07:00
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2015-01-02 12:34:29 +05:30
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2005-04-16 15:20:36 -07:00
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2006-10-26 16:20:58 +05:30
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2005-04-16 15:20:36 -07:00
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2013-04-29 00:08:16 +02:00
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2008-02-07 16:33:49 -05:00
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2005-04-16 15:20:36 -07:00
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2015-01-02 12:34:29 +05:30
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2005-04-16 15:20:36 -07:00
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2016-03-30 03:47:49 +02:00
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2015-06-10 02:11:45 +02:00
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2006-10-26 16:20:58 +05:30
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2013-04-29 00:08:16 +02:00
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2006-10-26 16:20:58 +05:30
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2015-01-02 12:34:28 +05:30
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2005-04-16 15:20:36 -07:00
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2008-02-07 16:33:49 -05:00
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2007-02-05 16:12:44 -08:00
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2005-04-16 15:20:36 -07:00
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2007-02-05 16:12:44 -08:00
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2014-03-04 12:42:15 -08:00
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2007-02-05 16:12:44 -08:00
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2014-03-04 12:42:15 -08:00
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2016-11-18 13:40:45 +01:00
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2014-03-04 12:42:15 -08:00
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2013-09-20 22:37:31 +05:30
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2014-03-04 12:42:15 -08:00
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2013-08-06 22:53:11 +05:30
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2008-02-07 16:33:49 -05:00
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2005-04-16 15:20:36 -07:00
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2016-03-21 15:46:25 +01:00
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2011-12-21 14:29:42 -08:00
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cpufreq: Use syscore_ops for boot CPU suspend/resume (v2)
The cpufreq subsystem uses sysdev suspend and resume for
executing cpufreq_suspend() and cpufreq_resume(), respectively,
during system suspend, after interrupts have been switched off on the
boot CPU, and during system resume, while interrupts are still off on
the boot CPU. In both cases the other CPUs are off-line at the
relevant point (either they have been switched off via CPU hotplug
during suspend, or they haven't been switched on yet during resume).
For this reason, although it may seem that cpufreq_suspend() and
cpufreq_resume() are executed for all CPUs in the system, they are
only called for the boot CPU in fact, which is quite confusing.
To remove the confusion and to prepare for elimiating sysdev
suspend and resume operations from the kernel enirely, convernt
cpufreq to using a struct syscore_ops object for the boot CPU
suspend and resume and rename the callbacks so that their names
reflect their purpose. In addition, put some explanatory remarks
into their kerneldoc comments.
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
2011-03-23 22:16:32 +01:00
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2014-03-04 11:00:27 +08:00
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2005-04-29 07:40:12 -07:00
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2014-03-04 11:00:27 +08:00
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2005-04-29 07:40:12 -07:00
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2014-03-04 11:00:27 +08:00
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2009-08-04 14:03:25 -04:00
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2014-03-04 11:00:27 +08:00
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2015-09-08 18:41:02 +02:00
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2005-04-29 07:40:12 -07:00
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2014-03-04 11:00:27 +08:00
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2008-02-07 16:32:18 -05:00
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2005-04-29 07:40:12 -07:00
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2014-03-04 11:00:27 +08:00
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2005-04-29 07:40:12 -07:00
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2005-04-16 15:20:36 -07:00
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2014-03-04 11:00:26 +08:00
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2005-04-16 15:20:36 -07:00
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2014-03-04 11:00:26 +08:00
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2005-04-16 15:20:36 -07:00
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2014-03-04 11:00:26 +08:00
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2005-04-16 15:20:36 -07:00
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2013-08-06 22:53:05 +05:30
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2005-04-16 15:20:36 -07:00
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2014-03-04 11:00:26 +08:00
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|
cpufreq: Use syscore_ops for boot CPU suspend/resume (v2)
The cpufreq subsystem uses sysdev suspend and resume for
executing cpufreq_suspend() and cpufreq_resume(), respectively,
during system suspend, after interrupts have been switched off on the
boot CPU, and during system resume, while interrupts are still off on
the boot CPU. In both cases the other CPUs are off-line at the
relevant point (either they have been switched off via CPU hotplug
during suspend, or they haven't been switched on yet during resume).
For this reason, although it may seem that cpufreq_suspend() and
cpufreq_resume() are executed for all CPUs in the system, they are
only called for the boot CPU in fact, which is quite confusing.
To remove the confusion and to prepare for elimiating sysdev
suspend and resume operations from the kernel enirely, convernt
cpufreq to using a struct syscore_ops object for the boot CPU
suspend and resume and rename the callbacks so that their names
reflect their purpose. In addition, put some explanatory remarks
into their kerneldoc comments.
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
2011-03-23 22:16:32 +01:00
|
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|
2005-04-16 15:20:36 -07:00
|
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2016-05-02 02:27:19 +02:00
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2014-09-30 09:33:17 +05:30
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2005-04-29 07:40:12 -07:00
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2014-03-04 11:00:26 +08:00
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2015-05-12 12:20:11 +05:30
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2016-05-02 02:27:19 +02:00
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2016-05-12 15:14:12 +02:00
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2016-05-02 02:27:19 +02:00
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2014-03-04 11:00:26 +08:00
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2005-04-16 15:20:36 -07:00
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2014-09-30 09:33:17 +05:30
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2005-04-16 15:20:36 -07:00
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2014-03-04 11:00:26 +08:00
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2005-04-16 15:20:36 -07:00
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2014-03-04 11:00:26 +08:00
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2005-04-16 15:20:36 -07:00
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2014-03-04 11:00:26 +08:00
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2005-04-16 15:20:36 -07:00
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2013-08-06 22:53:05 +05:30
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2016-02-11 17:31:12 +05:30
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2005-04-16 15:20:36 -07:00
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2014-03-04 11:00:26 +08:00
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|
cpufreq: Use syscore_ops for boot CPU suspend/resume (v2)
The cpufreq subsystem uses sysdev suspend and resume for
executing cpufreq_suspend() and cpufreq_resume(), respectively,
during system suspend, after interrupts have been switched off on the
boot CPU, and during system resume, while interrupts are still off on
the boot CPU. In both cases the other CPUs are off-line at the
relevant point (either they have been switched off via CPU hotplug
during suspend, or they haven't been switched on yet during resume).
For this reason, although it may seem that cpufreq_suspend() and
cpufreq_resume() are executed for all CPUs in the system, they are
only called for the boot CPU in fact, which is quite confusing.
To remove the confusion and to prepare for elimiating sysdev
suspend and resume operations from the kernel enirely, convernt
cpufreq to using a struct syscore_ops object for the boot CPU
suspend and resume and rename the callbacks so that their names
reflect their purpose. In addition, put some explanatory remarks
into their kerneldoc comments.
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
2011-03-23 22:16:32 +01:00
|
|
|
|
2005-04-16 15:20:36 -07:00
|
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2014-09-18 15:03:07 +08:00
|
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2016-05-02 02:27:19 +02:00
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2014-03-04 11:00:26 +08:00
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2015-05-12 12:20:11 +05:30
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2016-02-11 17:31:12 +05:30
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2014-03-24 12:30:29 +05:30
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2016-05-02 02:27:19 +02:00
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2016-02-11 17:31:12 +05:30
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2016-03-21 15:45:24 +01:00
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2016-02-11 17:31:12 +05:30
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2005-04-16 15:20:36 -07:00
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2013-01-20 10:24:28 +00:00
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2013-04-29 00:08:16 +02:00
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2013-01-20 10:24:28 +00:00
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2005-04-16 15:20:36 -07:00
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2014-10-19 11:30:27 +02:00
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2005-04-16 15:20:36 -07:00
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2006-02-28 00:43:23 -05:00
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2005-04-16 15:20:36 -07:00
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[PATCH] Notifier chain update: API changes
The kernel's implementation of notifier chains is unsafe. There is no
protection against entries being added to or removed from a chain while the
chain is in use. The issues were discussed in this thread:
http://marc.theaimsgroup.com/?l=linux-kernel&m=113018709002036&w=2
We noticed that notifier chains in the kernel fall into two basic usage
classes:
"Blocking" chains are always called from a process context
and the callout routines are allowed to sleep;
"Atomic" chains can be called from an atomic context and
the callout routines are not allowed to sleep.
We decided to codify this distinction and make it part of the API. Therefore
this set of patches introduces three new, parallel APIs: one for blocking
notifiers, one for atomic notifiers, and one for "raw" notifiers (which is
really just the old API under a new name). New kinds of data structures are
used for the heads of the chains, and new routines are defined for
registration, unregistration, and calling a chain. The three APIs are
explained in include/linux/notifier.h and their implementation is in
kernel/sys.c.
With atomic and blocking chains, the implementation guarantees that the chain
links will not be corrupted and that chain callers will not get messed up by
entries being added or removed. For raw chains the implementation provides no
guarantees at all; users of this API must provide their own protections. (The
idea was that situations may come up where the assumptions of the atomic and
blocking APIs are not appropriate, so it should be possible for users to
handle these things in their own way.)
There are some limitations, which should not be too hard to live with. For
atomic/blocking chains, registration and unregistration must always be done in
a process context since the chain is protected by a mutex/rwsem. Also, a
callout routine for a non-raw chain must not try to register or unregister
entries on its own chain. (This did happen in a couple of places and the code
had to be changed to avoid it.)
Since atomic chains may be called from within an NMI handler, they cannot use
spinlocks for synchronization. Instead we use RCU. The overhead falls almost
entirely in the unregister routine, which is okay since unregistration is much
less frequent that calling a chain.
Here is the list of chains that we adjusted and their classifications. None
of them use the raw API, so for the moment it is only a placeholder.
ATOMIC CHAINS
-------------
arch/i386/kernel/traps.c: i386die_chain
arch/ia64/kernel/traps.c: ia64die_chain
arch/powerpc/kernel/traps.c: powerpc_die_chain
arch/sparc64/kernel/traps.c: sparc64die_chain
arch/x86_64/kernel/traps.c: die_chain
drivers/char/ipmi/ipmi_si_intf.c: xaction_notifier_list
kernel/panic.c: panic_notifier_list
kernel/profile.c: task_free_notifier
net/bluetooth/hci_core.c: hci_notifier
net/ipv4/netfilter/ip_conntrack_core.c: ip_conntrack_chain
net/ipv4/netfilter/ip_conntrack_core.c: ip_conntrack_expect_chain
net/ipv6/addrconf.c: inet6addr_chain
net/netfilter/nf_conntrack_core.c: nf_conntrack_chain
net/netfilter/nf_conntrack_core.c: nf_conntrack_expect_chain
net/netlink/af_netlink.c: netlink_chain
BLOCKING CHAINS
---------------
arch/powerpc/platforms/pseries/reconfig.c: pSeries_reconfig_chain
arch/s390/kernel/process.c: idle_chain
arch/x86_64/kernel/process.c idle_notifier
drivers/base/memory.c: memory_chain
drivers/cpufreq/cpufreq.c cpufreq_policy_notifier_list
drivers/cpufreq/cpufreq.c cpufreq_transition_notifier_list
drivers/macintosh/adb.c: adb_client_list
drivers/macintosh/via-pmu.c sleep_notifier_list
drivers/macintosh/via-pmu68k.c sleep_notifier_list
drivers/macintosh/windfarm_core.c wf_client_list
drivers/usb/core/notify.c usb_notifier_list
drivers/video/fbmem.c fb_notifier_list
kernel/cpu.c cpu_chain
kernel/module.c module_notify_list
kernel/profile.c munmap_notifier
kernel/profile.c task_exit_notifier
kernel/sys.c reboot_notifier_list
net/core/dev.c netdev_chain
net/decnet/dn_dev.c: dnaddr_chain
net/ipv4/devinet.c: inetaddr_chain
It's possible that some of these classifications are wrong. If they are,
please let us know or submit a patch to fix them. Note that any chain that
gets called very frequently should be atomic, because the rwsem read-locking
used for blocking chains is very likely to incur cache misses on SMP systems.
(However, if the chain's callout routines may sleep then the chain cannot be
atomic.)
The patch set was written by Alan Stern and Chandra Seetharaman, incorporating
material written by Keith Owens and suggestions from Paul McKenney and Andrew
Morton.
[jes@sgi.com: restructure the notifier chain initialization macros]
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Chandra Seetharaman <sekharan@us.ibm.com>
Signed-off-by: Jes Sorensen <jes@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-27 01:16:30 -08:00
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2005-04-16 15:20:36 -07:00
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2013-01-17 16:22:21 +00:00
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2008-02-16 08:41:24 -02:00
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2005-04-16 15:20:36 -07:00
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2016-03-30 03:47:49 +02:00
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2006-10-04 02:17:06 -07:00
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[PATCH] Notifier chain update: API changes
The kernel's implementation of notifier chains is unsafe. There is no
protection against entries being added to or removed from a chain while the
chain is in use. The issues were discussed in this thread:
http://marc.theaimsgroup.com/?l=linux-kernel&m=113018709002036&w=2
We noticed that notifier chains in the kernel fall into two basic usage
classes:
"Blocking" chains are always called from a process context
and the callout routines are allowed to sleep;
"Atomic" chains can be called from an atomic context and
the callout routines are not allowed to sleep.
We decided to codify this distinction and make it part of the API. Therefore
this set of patches introduces three new, parallel APIs: one for blocking
notifiers, one for atomic notifiers, and one for "raw" notifiers (which is
really just the old API under a new name). New kinds of data structures are
used for the heads of the chains, and new routines are defined for
registration, unregistration, and calling a chain. The three APIs are
explained in include/linux/notifier.h and their implementation is in
kernel/sys.c.
With atomic and blocking chains, the implementation guarantees that the chain
links will not be corrupted and that chain callers will not get messed up by
entries being added or removed. For raw chains the implementation provides no
guarantees at all; users of this API must provide their own protections. (The
idea was that situations may come up where the assumptions of the atomic and
blocking APIs are not appropriate, so it should be possible for users to
handle these things in their own way.)
There are some limitations, which should not be too hard to live with. For
atomic/blocking chains, registration and unregistration must always be done in
a process context since the chain is protected by a mutex/rwsem. Also, a
callout routine for a non-raw chain must not try to register or unregister
entries on its own chain. (This did happen in a couple of places and the code
had to be changed to avoid it.)
Since atomic chains may be called from within an NMI handler, they cannot use
spinlocks for synchronization. Instead we use RCU. The overhead falls almost
entirely in the unregister routine, which is okay since unregistration is much
less frequent that calling a chain.
Here is the list of chains that we adjusted and their classifications. None
of them use the raw API, so for the moment it is only a placeholder.
ATOMIC CHAINS
-------------
arch/i386/kernel/traps.c: i386die_chain
arch/ia64/kernel/traps.c: ia64die_chain
arch/powerpc/kernel/traps.c: powerpc_die_chain
arch/sparc64/kernel/traps.c: sparc64die_chain
arch/x86_64/kernel/traps.c: die_chain
drivers/char/ipmi/ipmi_si_intf.c: xaction_notifier_list
kernel/panic.c: panic_notifier_list
kernel/profile.c: task_free_notifier
net/bluetooth/hci_core.c: hci_notifier
net/ipv4/netfilter/ip_conntrack_core.c: ip_conntrack_chain
net/ipv4/netfilter/ip_conntrack_core.c: ip_conntrack_expect_chain
net/ipv6/addrconf.c: inet6addr_chain
net/netfilter/nf_conntrack_core.c: nf_conntrack_chain
net/netfilter/nf_conntrack_core.c: nf_conntrack_expect_chain
net/netlink/af_netlink.c: netlink_chain
BLOCKING CHAINS
---------------
arch/powerpc/platforms/pseries/reconfig.c: pSeries_reconfig_chain
arch/s390/kernel/process.c: idle_chain
arch/x86_64/kernel/process.c idle_notifier
drivers/base/memory.c: memory_chain
drivers/cpufreq/cpufreq.c cpufreq_policy_notifier_list
drivers/cpufreq/cpufreq.c cpufreq_transition_notifier_list
drivers/macintosh/adb.c: adb_client_list
drivers/macintosh/via-pmu.c sleep_notifier_list
drivers/macintosh/via-pmu68k.c sleep_notifier_list
drivers/macintosh/windfarm_core.c wf_client_list
drivers/usb/core/notify.c usb_notifier_list
drivers/video/fbmem.c fb_notifier_list
kernel/cpu.c cpu_chain
kernel/module.c module_notify_list
kernel/profile.c munmap_notifier
kernel/profile.c task_exit_notifier
kernel/sys.c reboot_notifier_list
net/core/dev.c netdev_chain
net/decnet/dn_dev.c: dnaddr_chain
net/ipv4/devinet.c: inetaddr_chain
It's possible that some of these classifications are wrong. If they are,
please let us know or submit a patch to fix them. Note that any chain that
gets called very frequently should be atomic, because the rwsem read-locking
used for blocking chains is very likely to incur cache misses on SMP systems.
(However, if the chain's callout routines may sleep then the chain cannot be
atomic.)
The patch set was written by Alan Stern and Chandra Seetharaman, incorporating
material written by Keith Owens and suggestions from Paul McKenney and Andrew
Morton.
[jes@sgi.com: restructure the notifier chain initialization macros]
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Chandra Seetharaman <sekharan@us.ibm.com>
Signed-off-by: Jes Sorensen <jes@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-27 01:16:30 -08:00
|
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|
2016-03-30 03:47:49 +02:00
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2005-04-16 15:20:36 -07:00
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|
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|
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|
[PATCH] Notifier chain update: API changes
The kernel's implementation of notifier chains is unsafe. There is no
protection against entries being added to or removed from a chain while the
chain is in use. The issues were discussed in this thread:
http://marc.theaimsgroup.com/?l=linux-kernel&m=113018709002036&w=2
We noticed that notifier chains in the kernel fall into two basic usage
classes:
"Blocking" chains are always called from a process context
and the callout routines are allowed to sleep;
"Atomic" chains can be called from an atomic context and
the callout routines are not allowed to sleep.
We decided to codify this distinction and make it part of the API. Therefore
this set of patches introduces three new, parallel APIs: one for blocking
notifiers, one for atomic notifiers, and one for "raw" notifiers (which is
really just the old API under a new name). New kinds of data structures are
used for the heads of the chains, and new routines are defined for
registration, unregistration, and calling a chain. The three APIs are
explained in include/linux/notifier.h and their implementation is in
kernel/sys.c.
With atomic and blocking chains, the implementation guarantees that the chain
links will not be corrupted and that chain callers will not get messed up by
entries being added or removed. For raw chains the implementation provides no
guarantees at all; users of this API must provide their own protections. (The
idea was that situations may come up where the assumptions of the atomic and
blocking APIs are not appropriate, so it should be possible for users to
handle these things in their own way.)
There are some limitations, which should not be too hard to live with. For
atomic/blocking chains, registration and unregistration must always be done in
a process context since the chain is protected by a mutex/rwsem. Also, a
callout routine for a non-raw chain must not try to register or unregister
entries on its own chain. (This did happen in a couple of places and the code
had to be changed to avoid it.)
Since atomic chains may be called from within an NMI handler, they cannot use
spinlocks for synchronization. Instead we use RCU. The overhead falls almost
entirely in the unregister routine, which is okay since unregistration is much
less frequent that calling a chain.
Here is the list of chains that we adjusted and their classifications. None
of them use the raw API, so for the moment it is only a placeholder.
ATOMIC CHAINS
-------------
arch/i386/kernel/traps.c: i386die_chain
arch/ia64/kernel/traps.c: ia64die_chain
arch/powerpc/kernel/traps.c: powerpc_die_chain
arch/sparc64/kernel/traps.c: sparc64die_chain
arch/x86_64/kernel/traps.c: die_chain
drivers/char/ipmi/ipmi_si_intf.c: xaction_notifier_list
kernel/panic.c: panic_notifier_list
kernel/profile.c: task_free_notifier
net/bluetooth/hci_core.c: hci_notifier
net/ipv4/netfilter/ip_conntrack_core.c: ip_conntrack_chain
net/ipv4/netfilter/ip_conntrack_core.c: ip_conntrack_expect_chain
net/ipv6/addrconf.c: inet6addr_chain
net/netfilter/nf_conntrack_core.c: nf_conntrack_chain
net/netfilter/nf_conntrack_core.c: nf_conntrack_expect_chain
net/netlink/af_netlink.c: netlink_chain
BLOCKING CHAINS
---------------
arch/powerpc/platforms/pseries/reconfig.c: pSeries_reconfig_chain
arch/s390/kernel/process.c: idle_chain
arch/x86_64/kernel/process.c idle_notifier
drivers/base/memory.c: memory_chain
drivers/cpufreq/cpufreq.c cpufreq_policy_notifier_list
drivers/cpufreq/cpufreq.c cpufreq_transition_notifier_list
drivers/macintosh/adb.c: adb_client_list
drivers/macintosh/via-pmu.c sleep_notifier_list
drivers/macintosh/via-pmu68k.c sleep_notifier_list
drivers/macintosh/windfarm_core.c wf_client_list
drivers/usb/core/notify.c usb_notifier_list
drivers/video/fbmem.c fb_notifier_list
kernel/cpu.c cpu_chain
kernel/module.c module_notify_list
kernel/profile.c munmap_notifier
kernel/profile.c task_exit_notifier
kernel/sys.c reboot_notifier_list
net/core/dev.c netdev_chain
net/decnet/dn_dev.c: dnaddr_chain
net/ipv4/devinet.c: inetaddr_chain
It's possible that some of these classifications are wrong. If they are,
please let us know or submit a patch to fix them. Note that any chain that
gets called very frequently should be atomic, because the rwsem read-locking
used for blocking chains is very likely to incur cache misses on SMP systems.
(However, if the chain's callout routines may sleep then the chain cannot be
atomic.)
The patch set was written by Alan Stern and Chandra Seetharaman, incorporating
material written by Keith Owens and suggestions from Paul McKenney and Andrew
Morton.
[jes@sgi.com: restructure the notifier chain initialization macros]
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Chandra Seetharaman <sekharan@us.ibm.com>
Signed-off-by: Jes Sorensen <jes@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-27 01:16:30 -08:00
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2005-04-16 15:20:36 -07:00
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2013-06-19 14:19:33 +05:30
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2005-04-16 15:20:36 -07:00
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[PATCH] Notifier chain update: API changes
The kernel's implementation of notifier chains is unsafe. There is no
protection against entries being added to or removed from a chain while the
chain is in use. The issues were discussed in this thread:
http://marc.theaimsgroup.com/?l=linux-kernel&m=113018709002036&w=2
We noticed that notifier chains in the kernel fall into two basic usage
classes:
"Blocking" chains are always called from a process context
and the callout routines are allowed to sleep;
"Atomic" chains can be called from an atomic context and
the callout routines are not allowed to sleep.
We decided to codify this distinction and make it part of the API. Therefore
this set of patches introduces three new, parallel APIs: one for blocking
notifiers, one for atomic notifiers, and one for "raw" notifiers (which is
really just the old API under a new name). New kinds of data structures are
used for the heads of the chains, and new routines are defined for
registration, unregistration, and calling a chain. The three APIs are
explained in include/linux/notifier.h and their implementation is in
kernel/sys.c.
With atomic and blocking chains, the implementation guarantees that the chain
links will not be corrupted and that chain callers will not get messed up by
entries being added or removed. For raw chains the implementation provides no
guarantees at all; users of this API must provide their own protections. (The
idea was that situations may come up where the assumptions of the atomic and
blocking APIs are not appropriate, so it should be possible for users to
handle these things in their own way.)
There are some limitations, which should not be too hard to live with. For
atomic/blocking chains, registration and unregistration must always be done in
a process context since the chain is protected by a mutex/rwsem. Also, a
callout routine for a non-raw chain must not try to register or unregister
entries on its own chain. (This did happen in a couple of places and the code
had to be changed to avoid it.)
Since atomic chains may be called from within an NMI handler, they cannot use
spinlocks for synchronization. Instead we use RCU. The overhead falls almost
entirely in the unregister routine, which is okay since unregistration is much
less frequent that calling a chain.
Here is the list of chains that we adjusted and their classifications. None
of them use the raw API, so for the moment it is only a placeholder.
ATOMIC CHAINS
-------------
arch/i386/kernel/traps.c: i386die_chain
arch/ia64/kernel/traps.c: ia64die_chain
arch/powerpc/kernel/traps.c: powerpc_die_chain
arch/sparc64/kernel/traps.c: sparc64die_chain
arch/x86_64/kernel/traps.c: die_chain
drivers/char/ipmi/ipmi_si_intf.c: xaction_notifier_list
kernel/panic.c: panic_notifier_list
kernel/profile.c: task_free_notifier
net/bluetooth/hci_core.c: hci_notifier
net/ipv4/netfilter/ip_conntrack_core.c: ip_conntrack_chain
net/ipv4/netfilter/ip_conntrack_core.c: ip_conntrack_expect_chain
net/ipv6/addrconf.c: inet6addr_chain
net/netfilter/nf_conntrack_core.c: nf_conntrack_chain
net/netfilter/nf_conntrack_core.c: nf_conntrack_expect_chain
net/netlink/af_netlink.c: netlink_chain
BLOCKING CHAINS
---------------
arch/powerpc/platforms/pseries/reconfig.c: pSeries_reconfig_chain
arch/s390/kernel/process.c: idle_chain
arch/x86_64/kernel/process.c idle_notifier
drivers/base/memory.c: memory_chain
drivers/cpufreq/cpufreq.c cpufreq_policy_notifier_list
drivers/cpufreq/cpufreq.c cpufreq_transition_notifier_list
drivers/macintosh/adb.c: adb_client_list
drivers/macintosh/via-pmu.c sleep_notifier_list
drivers/macintosh/via-pmu68k.c sleep_notifier_list
drivers/macintosh/windfarm_core.c wf_client_list
drivers/usb/core/notify.c usb_notifier_list
drivers/video/fbmem.c fb_notifier_list
kernel/cpu.c cpu_chain
kernel/module.c module_notify_list
kernel/profile.c munmap_notifier
kernel/profile.c task_exit_notifier
kernel/sys.c reboot_notifier_list
net/core/dev.c netdev_chain
net/decnet/dn_dev.c: dnaddr_chain
net/ipv4/devinet.c: inetaddr_chain
It's possible that some of these classifications are wrong. If they are,
please let us know or submit a patch to fix them. Note that any chain that
gets called very frequently should be atomic, because the rwsem read-locking
used for blocking chains is very likely to incur cache misses on SMP systems.
(However, if the chain's callout routines may sleep then the chain cannot be
atomic.)
The patch set was written by Alan Stern and Chandra Seetharaman, incorporating
material written by Keith Owens and suggestions from Paul McKenney and Andrew
Morton.
[jes@sgi.com: restructure the notifier chain initialization macros]
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Chandra Seetharaman <sekharan@us.ibm.com>
Signed-off-by: Jes Sorensen <jes@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-27 01:16:30 -08:00
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2005-04-16 15:20:36 -07:00
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2013-01-17 16:22:21 +00:00
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2005-04-16 15:20:36 -07:00
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2016-03-30 03:47:49 +02:00
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2006-10-04 02:17:06 -07:00
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[PATCH] Notifier chain update: API changes
The kernel's implementation of notifier chains is unsafe. There is no
protection against entries being added to or removed from a chain while the
chain is in use. The issues were discussed in this thread:
http://marc.theaimsgroup.com/?l=linux-kernel&m=113018709002036&w=2
We noticed that notifier chains in the kernel fall into two basic usage
classes:
"Blocking" chains are always called from a process context
and the callout routines are allowed to sleep;
"Atomic" chains can be called from an atomic context and
the callout routines are not allowed to sleep.
We decided to codify this distinction and make it part of the API. Therefore
this set of patches introduces three new, parallel APIs: one for blocking
notifiers, one for atomic notifiers, and one for "raw" notifiers (which is
really just the old API under a new name). New kinds of data structures are
used for the heads of the chains, and new routines are defined for
registration, unregistration, and calling a chain. The three APIs are
explained in include/linux/notifier.h and their implementation is in
kernel/sys.c.
With atomic and blocking chains, the implementation guarantees that the chain
links will not be corrupted and that chain callers will not get messed up by
entries being added or removed. For raw chains the implementation provides no
guarantees at all; users of this API must provide their own protections. (The
idea was that situations may come up where the assumptions of the atomic and
blocking APIs are not appropriate, so it should be possible for users to
handle these things in their own way.)
There are some limitations, which should not be too hard to live with. For
atomic/blocking chains, registration and unregistration must always be done in
a process context since the chain is protected by a mutex/rwsem. Also, a
callout routine for a non-raw chain must not try to register or unregister
entries on its own chain. (This did happen in a couple of places and the code
had to be changed to avoid it.)
Since atomic chains may be called from within an NMI handler, they cannot use
spinlocks for synchronization. Instead we use RCU. The overhead falls almost
entirely in the unregister routine, which is okay since unregistration is much
less frequent that calling a chain.
Here is the list of chains that we adjusted and their classifications. None
of them use the raw API, so for the moment it is only a placeholder.
ATOMIC CHAINS
-------------
arch/i386/kernel/traps.c: i386die_chain
arch/ia64/kernel/traps.c: ia64die_chain
arch/powerpc/kernel/traps.c: powerpc_die_chain
arch/sparc64/kernel/traps.c: sparc64die_chain
arch/x86_64/kernel/traps.c: die_chain
drivers/char/ipmi/ipmi_si_intf.c: xaction_notifier_list
kernel/panic.c: panic_notifier_list
kernel/profile.c: task_free_notifier
net/bluetooth/hci_core.c: hci_notifier
net/ipv4/netfilter/ip_conntrack_core.c: ip_conntrack_chain
net/ipv4/netfilter/ip_conntrack_core.c: ip_conntrack_expect_chain
net/ipv6/addrconf.c: inet6addr_chain
net/netfilter/nf_conntrack_core.c: nf_conntrack_chain
net/netfilter/nf_conntrack_core.c: nf_conntrack_expect_chain
net/netlink/af_netlink.c: netlink_chain
BLOCKING CHAINS
---------------
arch/powerpc/platforms/pseries/reconfig.c: pSeries_reconfig_chain
arch/s390/kernel/process.c: idle_chain
arch/x86_64/kernel/process.c idle_notifier
drivers/base/memory.c: memory_chain
drivers/cpufreq/cpufreq.c cpufreq_policy_notifier_list
drivers/cpufreq/cpufreq.c cpufreq_transition_notifier_list
drivers/macintosh/adb.c: adb_client_list
drivers/macintosh/via-pmu.c sleep_notifier_list
drivers/macintosh/via-pmu68k.c sleep_notifier_list
drivers/macintosh/windfarm_core.c wf_client_list
drivers/usb/core/notify.c usb_notifier_list
drivers/video/fbmem.c fb_notifier_list
kernel/cpu.c cpu_chain
kernel/module.c module_notify_list
kernel/profile.c munmap_notifier
kernel/profile.c task_exit_notifier
kernel/sys.c reboot_notifier_list
net/core/dev.c netdev_chain
net/decnet/dn_dev.c: dnaddr_chain
net/ipv4/devinet.c: inetaddr_chain
It's possible that some of these classifications are wrong. If they are,
please let us know or submit a patch to fix them. Note that any chain that
gets called very frequently should be atomic, because the rwsem read-locking
used for blocking chains is very likely to incur cache misses on SMP systems.
(However, if the chain's callout routines may sleep then the chain cannot be
atomic.)
The patch set was written by Alan Stern and Chandra Seetharaman, incorporating
material written by Keith Owens and suggestions from Paul McKenney and Andrew
Morton.
[jes@sgi.com: restructure the notifier chain initialization macros]
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Chandra Seetharaman <sekharan@us.ibm.com>
Signed-off-by: Jes Sorensen <jes@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-27 01:16:30 -08:00
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2016-03-30 03:47:49 +02:00
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2005-04-16 15:20:36 -07:00
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|
[PATCH] Notifier chain update: API changes
The kernel's implementation of notifier chains is unsafe. There is no
protection against entries being added to or removed from a chain while the
chain is in use. The issues were discussed in this thread:
http://marc.theaimsgroup.com/?l=linux-kernel&m=113018709002036&w=2
We noticed that notifier chains in the kernel fall into two basic usage
classes:
"Blocking" chains are always called from a process context
and the callout routines are allowed to sleep;
"Atomic" chains can be called from an atomic context and
the callout routines are not allowed to sleep.
We decided to codify this distinction and make it part of the API. Therefore
this set of patches introduces three new, parallel APIs: one for blocking
notifiers, one for atomic notifiers, and one for "raw" notifiers (which is
really just the old API under a new name). New kinds of data structures are
used for the heads of the chains, and new routines are defined for
registration, unregistration, and calling a chain. The three APIs are
explained in include/linux/notifier.h and their implementation is in
kernel/sys.c.
With atomic and blocking chains, the implementation guarantees that the chain
links will not be corrupted and that chain callers will not get messed up by
entries being added or removed. For raw chains the implementation provides no
guarantees at all; users of this API must provide their own protections. (The
idea was that situations may come up where the assumptions of the atomic and
blocking APIs are not appropriate, so it should be possible for users to
handle these things in their own way.)
There are some limitations, which should not be too hard to live with. For
atomic/blocking chains, registration and unregistration must always be done in
a process context since the chain is protected by a mutex/rwsem. Also, a
callout routine for a non-raw chain must not try to register or unregister
entries on its own chain. (This did happen in a couple of places and the code
had to be changed to avoid it.)
Since atomic chains may be called from within an NMI handler, they cannot use
spinlocks for synchronization. Instead we use RCU. The overhead falls almost
entirely in the unregister routine, which is okay since unregistration is much
less frequent that calling a chain.
Here is the list of chains that we adjusted and their classifications. None
of them use the raw API, so for the moment it is only a placeholder.
ATOMIC CHAINS
-------------
arch/i386/kernel/traps.c: i386die_chain
arch/ia64/kernel/traps.c: ia64die_chain
arch/powerpc/kernel/traps.c: powerpc_die_chain
arch/sparc64/kernel/traps.c: sparc64die_chain
arch/x86_64/kernel/traps.c: die_chain
drivers/char/ipmi/ipmi_si_intf.c: xaction_notifier_list
kernel/panic.c: panic_notifier_list
kernel/profile.c: task_free_notifier
net/bluetooth/hci_core.c: hci_notifier
net/ipv4/netfilter/ip_conntrack_core.c: ip_conntrack_chain
net/ipv4/netfilter/ip_conntrack_core.c: ip_conntrack_expect_chain
net/ipv6/addrconf.c: inet6addr_chain
net/netfilter/nf_conntrack_core.c: nf_conntrack_chain
net/netfilter/nf_conntrack_core.c: nf_conntrack_expect_chain
net/netlink/af_netlink.c: netlink_chain
BLOCKING CHAINS
---------------
arch/powerpc/platforms/pseries/reconfig.c: pSeries_reconfig_chain
arch/s390/kernel/process.c: idle_chain
arch/x86_64/kernel/process.c idle_notifier
drivers/base/memory.c: memory_chain
drivers/cpufreq/cpufreq.c cpufreq_policy_notifier_list
drivers/cpufreq/cpufreq.c cpufreq_transition_notifier_list
drivers/macintosh/adb.c: adb_client_list
drivers/macintosh/via-pmu.c sleep_notifier_list
drivers/macintosh/via-pmu68k.c sleep_notifier_list
drivers/macintosh/windfarm_core.c wf_client_list
drivers/usb/core/notify.c usb_notifier_list
drivers/video/fbmem.c fb_notifier_list
kernel/cpu.c cpu_chain
kernel/module.c module_notify_list
kernel/profile.c munmap_notifier
kernel/profile.c task_exit_notifier
kernel/sys.c reboot_notifier_list
net/core/dev.c netdev_chain
net/decnet/dn_dev.c: dnaddr_chain
net/ipv4/devinet.c: inetaddr_chain
It's possible that some of these classifications are wrong. If they are,
please let us know or submit a patch to fix them. Note that any chain that
gets called very frequently should be atomic, because the rwsem read-locking
used for blocking chains is very likely to incur cache misses on SMP systems.
(However, if the chain's callout routines may sleep then the chain cannot be
atomic.)
The patch set was written by Alan Stern and Chandra Seetharaman, incorporating
material written by Keith Owens and suggestions from Paul McKenney and Andrew
Morton.
[jes@sgi.com: restructure the notifier chain initialization macros]
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Chandra Seetharaman <sekharan@us.ibm.com>
Signed-off-by: Jes Sorensen <jes@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-27 01:16:30 -08:00
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2005-04-16 15:20:36 -07:00
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2016-03-30 03:47:49 +02:00
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2017-08-09 10:21:46 +05:30
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2016-03-30 03:47:49 +02:00
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2016-06-01 22:36:26 +02:00
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2016-03-30 03:47:49 +02:00
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2014-06-02 22:49:28 +05:30
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2016-06-03 10:58:50 +05:30
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2014-05-21 14:29:29 +05:30
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2014-06-02 22:49:28 +05:30
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2016-06-03 10:58:50 +05:30
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2014-05-21 14:29:29 +05:30
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2016-06-03 10:58:50 +05:30
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2014-05-21 14:29:29 +05:30
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2014-06-02 22:49:28 +05:30
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2014-05-21 14:29:29 +05:30
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2014-06-02 22:49:28 +05:30
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2016-06-03 10:58:50 +05:30
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2014-05-21 14:29:29 +05:30
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2014-06-02 22:49:28 +05:30
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2014-05-21 14:29:29 +05:30
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2014-06-02 22:49:28 +05:30
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2015-05-22 22:48:22 +05:30
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2014-06-02 22:49:28 +05:30
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2014-05-21 14:29:29 +05:30
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2005-04-16 15:20:36 -07:00
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2012-10-31 01:28:21 +01:00
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2016-06-03 10:58:51 +05:30
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2005-10-30 14:59:54 -08:00
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2012-03-13 19:18:39 -04:00
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2012-10-31 01:28:21 +01:00
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2016-05-26 11:27:24 +05:30
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2012-10-31 01:28:21 +01:00
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2014-03-11 10:03:00 -07:00
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2012-10-31 01:28:15 +01:00
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2013-10-25 19:45:48 +05:30
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2012-10-31 01:28:15 +01:00
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2014-06-02 22:49:28 +05:30
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2013-04-29 00:08:16 +02:00
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2016-02-26 00:03:01 +01:00
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2005-11-08 21:34:24 -08:00
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2016-02-26 00:03:01 +01:00
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2013-10-25 19:45:48 +05:30
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2016-06-03 10:58:51 +05:30
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2013-10-25 19:45:48 +05:30
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2016-06-03 10:58:50 +05:30
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2005-04-16 15:20:36 -07:00
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2008-07-25 22:44:53 +02:00
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2005-04-16 15:20:36 -07:00
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2013-10-18 19:10:15 +05:30
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2005-04-16 15:20:36 -07:00
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2013-10-18 19:10:15 +05:30
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2005-04-16 15:20:36 -07:00
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2016-02-05 02:37:42 +01:00
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2016-05-14 01:01:46 +02:00
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2005-04-16 15:20:36 -07:00
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2005-07-28 09:43:56 -07:00
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2007-10-02 13:28:13 -07:00
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2014-03-04 11:00:26 +08:00
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2014-12-18 15:28:19 +09:00
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2014-03-04 11:00:26 +08:00
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2017-07-19 15:42:46 +05:30
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2017-07-19 15:42:49 +05:30
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2016-02-05 02:37:42 +01:00
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2017-07-19 15:42:48 +05:30
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2014-03-11 10:03:00 -07:00
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2007-10-02 13:28:13 -07:00
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2016-02-05 02:37:42 +01:00
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2007-10-02 13:28:13 -07:00
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2007-10-02 13:28:12 -07:00
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2005-04-16 15:20:36 -07:00
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2016-05-14 01:01:46 +02:00
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2005-04-16 15:20:36 -07:00
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2016-05-14 01:01:46 +02:00
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cpufreq: Fix governor start/stop race condition
Cpufreq governors' stop and start operations should be carried out
in sequence. Otherwise, there will be unexpected behavior, like in
the example below.
Suppose there are 4 CPUs and policy->cpu=CPU0, CPU1/2/3 are linked
to CPU0. The normal sequence is:
1) Current governor is userspace. An application tries to set the
governor to ondemand. It will call __cpufreq_set_policy() in
which it will stop the userspace governor and then start the
ondemand governor.
2) Current governor is userspace. The online of CPU3 runs on CPU0.
It will call cpufreq_add_policy_cpu() in which it will first
stop the userspace governor, and then start it again.
If the sequence of the above two cases interleaves, it becomes:
1) Application stops userspace governor
2) Hotplug stops userspace governor
which is a problem, because the governor shouldn't be stopped twice
in a row. What happens next is:
3) Application starts ondemand governor
4) Hotplug starts a governor
In step 4, the hotplug is supposed to start the userspace governor,
but now the governor has been changed by the application to ondemand,
so the ondemand governor is started once again, which is incorrect.
The solution is to prevent policy governors from being stopped
multiple times in a row. A governor should only be stopped once for
one policy. After it has been stopped, no more governor stop
operations should be executed.
Also add a mutex to serialize governor operations.
[rjw: Changelog. And you owe me a beverage of my choice.]
Signed-off-by: Xiaoguang Chen <chenxg@marvell.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2013-06-19 15:00:07 +08:00
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2016-06-02 23:24:15 +02:00
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2016-05-12 15:13:35 +02:00
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2016-06-02 23:24:15 +02:00
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2016-05-12 15:13:35 +02:00
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2005-04-16 15:20:36 -07:00
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2016-05-14 01:01:46 +02:00
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2016-06-02 23:24:15 +02:00
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2016-05-14 01:01:46 +02:00
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2005-04-16 15:20:36 -07:00
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2016-03-21 15:45:24 +01:00
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2016-05-14 01:01:46 +02:00
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2016-03-21 15:47:48 +01:00
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2016-06-02 23:24:15 +02:00
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2016-05-14 00:59:27 +02:00
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2016-03-21 15:45:24 +01:00
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2016-05-14 01:01:46 +02:00
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2016-06-02 23:24:15 +02:00
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2016-05-14 01:01:46 +02:00
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2016-06-02 23:24:15 +02:00
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2016-03-21 15:45:24 +01:00
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2005-04-16 15:20:36 -07:00
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2006-07-06 12:30:26 -07:00
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2005-04-16 15:20:36 -07:00
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2012-03-13 19:18:39 -04:00
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2006-01-13 15:54:22 -08:00
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2006-02-28 00:43:23 -05:00
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2006-07-06 12:30:26 -07:00
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2015-01-02 12:34:26 +05:30
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2006-07-06 12:30:26 -07:00
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2005-04-16 15:20:36 -07:00
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2006-02-28 00:43:23 -05:00
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2006-07-06 12:30:26 -07:00
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2005-04-16 15:20:36 -07:00
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2015-05-12 12:22:34 +05:30
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2009-11-12 09:18:46 -05:00
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2005-04-16 15:20:36 -07:00
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2012-03-13 19:18:39 -04:00
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2015-05-12 12:22:34 +05:30
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2015-05-12 12:22:51 +05:30
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2015-05-12 12:22:34 +05:30
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2015-05-12 12:22:51 +05:30
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2009-11-12 09:18:46 -05:00
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2015-05-12 12:22:34 +05:30
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2009-11-12 09:18:46 -05:00
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2006-01-13 15:54:22 -08:00
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2005-04-16 15:20:36 -07:00
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2006-01-13 15:54:22 -08:00
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2005-04-16 15:20:36 -07:00
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2009-01-18 01:37:11 -05:00
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2005-04-16 15:20:36 -07:00
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2013-08-06 22:53:06 +05:30
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2005-04-16 15:20:36 -07:00
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2006-07-26 15:40:07 +02:00
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2013-10-02 14:13:16 +05:30
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2006-07-26 15:40:07 +02:00
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2013-10-02 14:13:16 +05:30
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2013-08-06 22:53:05 +05:30
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2005-04-16 15:20:36 -07:00
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2014-02-17 22:56:35 +01:00
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2005-04-16 15:20:36 -07:00
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2014-03-11 10:03:00 -07:00
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2005-04-16 15:20:36 -07:00
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2013-08-06 22:53:06 +05:30
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2005-04-16 15:20:36 -07:00
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2015-07-30 18:10:40 +08:00
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2014-02-17 22:56:35 +01:00
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2006-07-05 23:12:20 +02:00
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2005-04-16 15:20:36 -07:00
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2013-08-06 22:53:05 +05:30
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2005-04-16 15:20:36 -07:00
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2014-02-17 22:56:35 +01:00
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2005-04-16 15:20:36 -07:00
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[PATCH] Notifier chain update: API changes
The kernel's implementation of notifier chains is unsafe. There is no
protection against entries being added to or removed from a chain while the
chain is in use. The issues were discussed in this thread:
http://marc.theaimsgroup.com/?l=linux-kernel&m=113018709002036&w=2
We noticed that notifier chains in the kernel fall into two basic usage
classes:
"Blocking" chains are always called from a process context
and the callout routines are allowed to sleep;
"Atomic" chains can be called from an atomic context and
the callout routines are not allowed to sleep.
We decided to codify this distinction and make it part of the API. Therefore
this set of patches introduces three new, parallel APIs: one for blocking
notifiers, one for atomic notifiers, and one for "raw" notifiers (which is
really just the old API under a new name). New kinds of data structures are
used for the heads of the chains, and new routines are defined for
registration, unregistration, and calling a chain. The three APIs are
explained in include/linux/notifier.h and their implementation is in
kernel/sys.c.
With atomic and blocking chains, the implementation guarantees that the chain
links will not be corrupted and that chain callers will not get messed up by
entries being added or removed. For raw chains the implementation provides no
guarantees at all; users of this API must provide their own protections. (The
idea was that situations may come up where the assumptions of the atomic and
blocking APIs are not appropriate, so it should be possible for users to
handle these things in their own way.)
There are some limitations, which should not be too hard to live with. For
atomic/blocking chains, registration and unregistration must always be done in
a process context since the chain is protected by a mutex/rwsem. Also, a
callout routine for a non-raw chain must not try to register or unregister
entries on its own chain. (This did happen in a couple of places and the code
had to be changed to avoid it.)
Since atomic chains may be called from within an NMI handler, they cannot use
spinlocks for synchronization. Instead we use RCU. The overhead falls almost
entirely in the unregister routine, which is okay since unregistration is much
less frequent that calling a chain.
Here is the list of chains that we adjusted and their classifications. None
of them use the raw API, so for the moment it is only a placeholder.
ATOMIC CHAINS
-------------
arch/i386/kernel/traps.c: i386die_chain
arch/ia64/kernel/traps.c: ia64die_chain
arch/powerpc/kernel/traps.c: powerpc_die_chain
arch/sparc64/kernel/traps.c: sparc64die_chain
arch/x86_64/kernel/traps.c: die_chain
drivers/char/ipmi/ipmi_si_intf.c: xaction_notifier_list
kernel/panic.c: panic_notifier_list
kernel/profile.c: task_free_notifier
net/bluetooth/hci_core.c: hci_notifier
net/ipv4/netfilter/ip_conntrack_core.c: ip_conntrack_chain
net/ipv4/netfilter/ip_conntrack_core.c: ip_conntrack_expect_chain
net/ipv6/addrconf.c: inet6addr_chain
net/netfilter/nf_conntrack_core.c: nf_conntrack_chain
net/netfilter/nf_conntrack_core.c: nf_conntrack_expect_chain
net/netlink/af_netlink.c: netlink_chain
BLOCKING CHAINS
---------------
arch/powerpc/platforms/pseries/reconfig.c: pSeries_reconfig_chain
arch/s390/kernel/process.c: idle_chain
arch/x86_64/kernel/process.c idle_notifier
drivers/base/memory.c: memory_chain
drivers/cpufreq/cpufreq.c cpufreq_policy_notifier_list
drivers/cpufreq/cpufreq.c cpufreq_transition_notifier_list
drivers/macintosh/adb.c: adb_client_list
drivers/macintosh/via-pmu.c sleep_notifier_list
drivers/macintosh/via-pmu68k.c sleep_notifier_list
drivers/macintosh/windfarm_core.c wf_client_list
drivers/usb/core/notify.c usb_notifier_list
drivers/video/fbmem.c fb_notifier_list
kernel/cpu.c cpu_chain
kernel/module.c module_notify_list
kernel/profile.c munmap_notifier
kernel/profile.c task_exit_notifier
kernel/sys.c reboot_notifier_list
net/core/dev.c netdev_chain
net/decnet/dn_dev.c: dnaddr_chain
net/ipv4/devinet.c: inetaddr_chain
It's possible that some of these classifications are wrong. If they are,
please let us know or submit a patch to fix them. Note that any chain that
gets called very frequently should be atomic, because the rwsem read-locking
used for blocking chains is very likely to incur cache misses on SMP systems.
(However, if the chain's callout routines may sleep then the chain cannot be
atomic.)
The patch set was written by Alan Stern and Chandra Seetharaman, incorporating
material written by Keith Owens and suggestions from Paul McKenney and Andrew
Morton.
[jes@sgi.com: restructure the notifier chain initialization macros]
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Chandra Seetharaman <sekharan@us.ibm.com>
Signed-off-by: Jes Sorensen <jes@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-27 01:16:30 -08:00
|
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|
2013-08-06 22:53:05 +05:30
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|
2005-04-16 15:20:36 -07:00
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2013-06-19 14:19:33 +05:30
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2013-08-06 22:53:05 +05:30
|
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|
|
[PATCH] Notifier chain update: API changes
The kernel's implementation of notifier chains is unsafe. There is no
protection against entries being added to or removed from a chain while the
chain is in use. The issues were discussed in this thread:
http://marc.theaimsgroup.com/?l=linux-kernel&m=113018709002036&w=2
We noticed that notifier chains in the kernel fall into two basic usage
classes:
"Blocking" chains are always called from a process context
and the callout routines are allowed to sleep;
"Atomic" chains can be called from an atomic context and
the callout routines are not allowed to sleep.
We decided to codify this distinction and make it part of the API. Therefore
this set of patches introduces three new, parallel APIs: one for blocking
notifiers, one for atomic notifiers, and one for "raw" notifiers (which is
really just the old API under a new name). New kinds of data structures are
used for the heads of the chains, and new routines are defined for
registration, unregistration, and calling a chain. The three APIs are
explained in include/linux/notifier.h and their implementation is in
kernel/sys.c.
With atomic and blocking chains, the implementation guarantees that the chain
links will not be corrupted and that chain callers will not get messed up by
entries being added or removed. For raw chains the implementation provides no
guarantees at all; users of this API must provide their own protections. (The
idea was that situations may come up where the assumptions of the atomic and
blocking APIs are not appropriate, so it should be possible for users to
handle these things in their own way.)
There are some limitations, which should not be too hard to live with. For
atomic/blocking chains, registration and unregistration must always be done in
a process context since the chain is protected by a mutex/rwsem. Also, a
callout routine for a non-raw chain must not try to register or unregister
entries on its own chain. (This did happen in a couple of places and the code
had to be changed to avoid it.)
Since atomic chains may be called from within an NMI handler, they cannot use
spinlocks for synchronization. Instead we use RCU. The overhead falls almost
entirely in the unregister routine, which is okay since unregistration is much
less frequent that calling a chain.
Here is the list of chains that we adjusted and their classifications. None
of them use the raw API, so for the moment it is only a placeholder.
ATOMIC CHAINS
-------------
arch/i386/kernel/traps.c: i386die_chain
arch/ia64/kernel/traps.c: ia64die_chain
arch/powerpc/kernel/traps.c: powerpc_die_chain
arch/sparc64/kernel/traps.c: sparc64die_chain
arch/x86_64/kernel/traps.c: die_chain
drivers/char/ipmi/ipmi_si_intf.c: xaction_notifier_list
kernel/panic.c: panic_notifier_list
kernel/profile.c: task_free_notifier
net/bluetooth/hci_core.c: hci_notifier
net/ipv4/netfilter/ip_conntrack_core.c: ip_conntrack_chain
net/ipv4/netfilter/ip_conntrack_core.c: ip_conntrack_expect_chain
net/ipv6/addrconf.c: inet6addr_chain
net/netfilter/nf_conntrack_core.c: nf_conntrack_chain
net/netfilter/nf_conntrack_core.c: nf_conntrack_expect_chain
net/netlink/af_netlink.c: netlink_chain
BLOCKING CHAINS
---------------
arch/powerpc/platforms/pseries/reconfig.c: pSeries_reconfig_chain
arch/s390/kernel/process.c: idle_chain
arch/x86_64/kernel/process.c idle_notifier
drivers/base/memory.c: memory_chain
drivers/cpufreq/cpufreq.c cpufreq_policy_notifier_list
drivers/cpufreq/cpufreq.c cpufreq_transition_notifier_list
drivers/macintosh/adb.c: adb_client_list
drivers/macintosh/via-pmu.c sleep_notifier_list
drivers/macintosh/via-pmu68k.c sleep_notifier_list
drivers/macintosh/windfarm_core.c wf_client_list
drivers/usb/core/notify.c usb_notifier_list
drivers/video/fbmem.c fb_notifier_list
kernel/cpu.c cpu_chain
kernel/module.c module_notify_list
kernel/profile.c munmap_notifier
kernel/profile.c task_exit_notifier
kernel/sys.c reboot_notifier_list
net/core/dev.c netdev_chain
net/decnet/dn_dev.c: dnaddr_chain
net/ipv4/devinet.c: inetaddr_chain
It's possible that some of these classifications are wrong. If they are,
please let us know or submit a patch to fix them. Note that any chain that
gets called very frequently should be atomic, because the rwsem read-locking
used for blocking chains is very likely to incur cache misses on SMP systems.
(However, if the chain's callout routines may sleep then the chain cannot be
atomic.)
The patch set was written by Alan Stern and Chandra Seetharaman, incorporating
material written by Keith Owens and suggestions from Paul McKenney and Andrew
Morton.
[jes@sgi.com: restructure the notifier chain initialization macros]
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Chandra Seetharaman <sekharan@us.ibm.com>
Signed-off-by: Jes Sorensen <jes@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-27 01:16:30 -08:00
|
|
|
|
2014-02-17 22:56:35 +01:00
|
|
|
|
2005-04-16 15:20:36 -07:00
|
|
|
|
|
|
|
|
|
[PATCH] Notifier chain update: API changes
The kernel's implementation of notifier chains is unsafe. There is no
protection against entries being added to or removed from a chain while the
chain is in use. The issues were discussed in this thread:
http://marc.theaimsgroup.com/?l=linux-kernel&m=113018709002036&w=2
We noticed that notifier chains in the kernel fall into two basic usage
classes:
"Blocking" chains are always called from a process context
and the callout routines are allowed to sleep;
"Atomic" chains can be called from an atomic context and
the callout routines are not allowed to sleep.
We decided to codify this distinction and make it part of the API. Therefore
this set of patches introduces three new, parallel APIs: one for blocking
notifiers, one for atomic notifiers, and one for "raw" notifiers (which is
really just the old API under a new name). New kinds of data structures are
used for the heads of the chains, and new routines are defined for
registration, unregistration, and calling a chain. The three APIs are
explained in include/linux/notifier.h and their implementation is in
kernel/sys.c.
With atomic and blocking chains, the implementation guarantees that the chain
links will not be corrupted and that chain callers will not get messed up by
entries being added or removed. For raw chains the implementation provides no
guarantees at all; users of this API must provide their own protections. (The
idea was that situations may come up where the assumptions of the atomic and
blocking APIs are not appropriate, so it should be possible for users to
handle these things in their own way.)
There are some limitations, which should not be too hard to live with. For
atomic/blocking chains, registration and unregistration must always be done in
a process context since the chain is protected by a mutex/rwsem. Also, a
callout routine for a non-raw chain must not try to register or unregister
entries on its own chain. (This did happen in a couple of places and the code
had to be changed to avoid it.)
Since atomic chains may be called from within an NMI handler, they cannot use
spinlocks for synchronization. Instead we use RCU. The overhead falls almost
entirely in the unregister routine, which is okay since unregistration is much
less frequent that calling a chain.
Here is the list of chains that we adjusted and their classifications. None
of them use the raw API, so for the moment it is only a placeholder.
ATOMIC CHAINS
-------------
arch/i386/kernel/traps.c: i386die_chain
arch/ia64/kernel/traps.c: ia64die_chain
arch/powerpc/kernel/traps.c: powerpc_die_chain
arch/sparc64/kernel/traps.c: sparc64die_chain
arch/x86_64/kernel/traps.c: die_chain
drivers/char/ipmi/ipmi_si_intf.c: xaction_notifier_list
kernel/panic.c: panic_notifier_list
kernel/profile.c: task_free_notifier
net/bluetooth/hci_core.c: hci_notifier
net/ipv4/netfilter/ip_conntrack_core.c: ip_conntrack_chain
net/ipv4/netfilter/ip_conntrack_core.c: ip_conntrack_expect_chain
net/ipv6/addrconf.c: inet6addr_chain
net/netfilter/nf_conntrack_core.c: nf_conntrack_chain
net/netfilter/nf_conntrack_core.c: nf_conntrack_expect_chain
net/netlink/af_netlink.c: netlink_chain
BLOCKING CHAINS
---------------
arch/powerpc/platforms/pseries/reconfig.c: pSeries_reconfig_chain
arch/s390/kernel/process.c: idle_chain
arch/x86_64/kernel/process.c idle_notifier
drivers/base/memory.c: memory_chain
drivers/cpufreq/cpufreq.c cpufreq_policy_notifier_list
drivers/cpufreq/cpufreq.c cpufreq_transition_notifier_list
drivers/macintosh/adb.c: adb_client_list
drivers/macintosh/via-pmu.c sleep_notifier_list
drivers/macintosh/via-pmu68k.c sleep_notifier_list
drivers/macintosh/windfarm_core.c wf_client_list
drivers/usb/core/notify.c usb_notifier_list
drivers/video/fbmem.c fb_notifier_list
kernel/cpu.c cpu_chain
kernel/module.c module_notify_list
kernel/profile.c munmap_notifier
kernel/profile.c task_exit_notifier
kernel/sys.c reboot_notifier_list
net/core/dev.c netdev_chain
net/decnet/dn_dev.c: dnaddr_chain
net/ipv4/devinet.c: inetaddr_chain
It's possible that some of these classifications are wrong. If they are,
please let us know or submit a patch to fix them. Note that any chain that
gets called very frequently should be atomic, because the rwsem read-locking
used for blocking chains is very likely to incur cache misses on SMP systems.
(However, if the chain's callout routines may sleep then the chain cannot be
atomic.)
The patch set was written by Alan Stern and Chandra Seetharaman, incorporating
material written by Keith Owens and suggestions from Paul McKenney and Andrew
Morton.
[jes@sgi.com: restructure the notifier chain initialization macros]
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Chandra Seetharaman <sekharan@us.ibm.com>
Signed-off-by: Jes Sorensen <jes@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-27 01:16:30 -08:00
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2013-08-06 22:53:05 +05:30
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2005-04-16 15:20:36 -07:00
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2013-08-06 22:53:05 +05:30
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2005-04-16 15:20:36 -07:00
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2016-07-13 13:25:25 -07:00
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2011-03-27 15:04:46 +02:00
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2014-03-11 10:03:00 -07:00
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2005-04-16 15:20:36 -07:00
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2013-04-29 00:08:16 +02:00
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2013-08-06 22:53:05 +05:30
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2011-03-27 15:04:46 +02:00
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2014-02-17 22:56:35 +01:00
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2005-04-16 15:20:36 -07:00
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2016-03-21 15:45:24 +01:00
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2016-05-14 01:01:46 +02:00
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2016-05-14 00:59:27 +02:00
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2016-03-21 15:45:24 +01:00
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2014-02-17 22:56:35 +01:00
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2016-05-12 15:14:12 +02:00
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2016-05-12 15:13:35 +02:00
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2014-02-17 22:56:35 +01:00
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2016-05-14 01:01:46 +02:00
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2015-07-18 11:31:03 +05:30
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2016-03-21 15:45:24 +01:00
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2016-03-30 03:47:49 +02:00
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2014-02-17 22:56:35 +01:00
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2016-05-14 01:01:46 +02:00
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2015-07-18 11:31:03 +05:30
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2016-03-21 15:45:24 +01:00
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2014-02-17 22:56:35 +01:00
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2015-07-18 11:31:03 +05:30
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2005-04-16 15:20:36 -07:00
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2011-03-30 22:57:33 -03:00
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2005-04-16 15:20:36 -07:00
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2016-11-18 13:59:21 +01:00
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2005-04-16 15:20:36 -07:00
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2013-08-06 22:53:05 +05:30
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2005-04-16 15:20:36 -07:00
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2014-06-18 11:27:32 -07:00
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2016-11-18 13:59:21 +01:00
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2005-04-16 15:20:36 -07:00
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2013-10-18 19:10:15 +05:30
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2005-04-16 15:20:36 -07:00
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2016-11-18 13:59:21 +01:00
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2016-11-18 13:40:45 +01:00
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2011-03-27 15:04:46 +02:00
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2013-08-06 22:53:06 +05:30
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2013-08-06 22:53:05 +05:30
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2005-04-16 15:20:36 -07:00
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2013-06-19 14:19:33 +05:30
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2014-03-12 21:49:33 +01:00
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2016-11-18 13:59:21 +01:00
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2016-06-28 03:29:29 +02:00
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2016-11-18 13:59:21 +01:00
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2016-03-21 15:46:25 +01:00
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2016-11-18 13:59:21 +01:00
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2014-06-18 11:27:32 -07:00
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2006-01-26 18:46:33 +01:00
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2016-11-18 13:59:21 +01:00
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2005-04-16 15:20:36 -07:00
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2014-06-18 11:27:32 -07:00
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2013-10-18 19:10:15 +05:30
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2007-02-05 16:12:44 -08:00
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2013-08-06 22:53:05 +05:30
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2005-04-16 15:20:36 -07:00
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2013-12-20 15:24:49 +01:00
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2015-05-12 12:20:11 +05:30
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2016-06-03 10:58:47 +05:30
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2016-02-11 17:31:12 +05:30
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2016-06-03 10:58:47 +05:30
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2013-12-20 15:24:49 +01:00
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2016-06-03 10:58:47 +05:30
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2013-12-20 15:24:49 +01:00
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2014-03-11 10:03:00 -07:00
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2013-12-20 15:24:49 +01:00
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2015-12-27 00:23:48 +01:00
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2013-12-20 15:24:49 +01:00
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2015-12-27 00:27:38 +01:00
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2013-12-20 15:24:49 +01:00
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2015-07-29 16:23:09 +05:30
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2015-10-15 21:35:23 +05:30
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2015-07-29 16:23:09 +05:30
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2015-10-15 21:35:23 +05:30
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2015-07-29 16:23:09 +05:30
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2015-12-27 00:27:38 +01:00
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2015-07-29 16:23:09 +05:30
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2013-12-20 15:24:49 +01:00
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2005-04-16 15:20:36 -07:00
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2016-09-06 19:04:48 +02:00
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2005-04-16 15:20:36 -07:00
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cpufreq: Bring CPUs up even if cpufreq_online() failed
There is a report that after commit 27622b061eb4 ("cpufreq: Convert
to hotplug state machine"), the normal CPU offline/online cycle
fails on some platforms.
According to the ftrace result, this problem was triggered on
platforms using acpi-cpufreq as the default cpufreq driver,
and due to the lack of some ACPI freq method (eg. _PCT),
cpufreq_online() failed and returned a negative value, so the CPU
hotplug state machine rolled back the CPU online process. Actually,
from the user's perspective, the failure of cpufreq_online() should
not prevent that CPU from being brought up, although cpufreq might
not work on that CPU.
BTW, during system startup cpufreq_online() is not invoked via CPU
online but by the cpufreq device creation process, so the APs can be
brought up even though cpufreq_online() fails in that stage.
This patch ignores the return value of cpufreq_online/offline() and
lets the cpufreq framework deal with the failure. cpufreq_online()
itself will do a proper rollback in that case and if _PCT is missing,
the ACPI cpufreq driver will print a warning if the corresponding
debug options have been enabled.
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=194581
Fixes: 27622b061eb4 ("cpufreq: Convert to hotplug state machine")
Reported-and-tested-by: Tomasz Maciej Nowak <tmn505@gmail.com>
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Cc: 4.9+ <stable@vger.kernel.org> # 4.9+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2017-04-09 13:45:16 +08:00
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2005-04-16 15:20:36 -07:00
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2013-06-19 14:19:33 +05:30
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2016-02-20 21:50:01 -06:00
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2006-02-28 00:43:23 -05:00
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2005-04-16 15:20:36 -07:00
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2007-02-26 14:55:48 -08:00
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2005-04-16 15:20:36 -07:00
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2012-03-13 19:18:39 -04:00
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2005-04-16 15:20:36 -07:00
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2013-10-25 19:45:48 +05:30
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2014-03-19 12:48:30 +01:00
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2014-06-02 22:49:28 +05:30
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2005-04-16 15:20:36 -07:00
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2011-03-27 15:04:46 +02:00
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2005-04-16 15:20:36 -07:00
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2015-07-30 01:45:07 +02:00
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2017-05-24 10:15:20 +02:00
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2015-07-30 01:45:07 +02:00
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2013-02-22 16:24:34 +00:00
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2013-04-29 00:08:16 +02:00
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2013-02-22 16:24:34 +00:00
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2015-07-30 01:45:07 +02:00
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2005-04-16 15:20:36 -07:00
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2013-04-29 00:08:16 +02:00
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2013-02-22 16:24:34 +00:00
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2005-04-16 15:20:36 -07:00
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2015-01-02 12:34:30 +05:30
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2015-12-27 00:27:38 +01:00
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2013-12-20 15:24:49 +01:00
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2011-12-21 14:29:42 -08:00
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2011-03-01 17:41:10 +01:00
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2013-12-20 15:24:49 +01:00
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2005-04-16 15:20:36 -07:00
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2015-01-02 12:34:35 +05:30
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2005-04-16 15:20:36 -07:00
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2017-05-26 11:37:31 -04:00
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2015-01-02 12:34:35 +05:30
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2005-04-16 15:20:36 -07:00
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2017-05-24 10:15:20 +02:00
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2016-09-06 19:04:48 +02:00
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2016-09-20 16:56:28 +02:00
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2016-09-06 19:04:48 +02:00
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2011-03-27 15:04:46 +02:00
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2016-05-16 11:07:19 +00:00
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2015-07-30 01:45:07 +02:00
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2011-12-21 14:29:42 -08:00
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2013-12-20 15:24:49 +01:00
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2015-07-29 16:23:09 +05:30
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2011-03-01 17:41:10 +01:00
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2013-02-22 16:24:34 +00:00
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2013-04-29 00:08:16 +02:00
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2013-02-22 16:24:34 +00:00
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2016-05-16 11:07:19 +00:00
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2017-05-24 10:15:20 +02:00
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2016-05-16 11:07:19 +00:00
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2005-04-16 15:20:36 -07:00
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2013-06-19 14:19:33 +05:30
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2005-04-16 15:20:36 -07:00
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2007-02-26 14:55:48 -08:00
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2005-04-16 15:20:36 -07:00
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2013-04-29 00:08:16 +02:00
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2005-04-16 15:20:36 -07:00
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2011-03-27 15:04:46 +02:00
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2005-04-16 15:20:36 -07:00
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2015-07-22 17:59:11 +02:00
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2017-05-24 10:15:20 +02:00
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2011-12-21 14:29:42 -08:00
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2015-07-29 16:23:09 +05:30
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2017-05-24 10:15:20 +02:00
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2005-04-16 15:20:36 -07:00
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2013-02-22 16:24:34 +00:00
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2013-08-06 22:53:11 +05:30
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2013-04-29 00:08:16 +02:00
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2013-08-06 22:53:11 +05:30
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2013-02-22 16:24:34 +00:00
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2017-05-24 10:15:20 +02:00
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2005-04-16 15:20:36 -07:00
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2007-02-05 16:12:44 -08:00
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2014-12-23 22:09:48 -08:00
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2015-10-15 21:35:23 +05:30
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2007-02-05 16:12:44 -08:00
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2012-03-13 19:18:39 -04:00
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2015-10-15 21:35:22 +05:30
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2009-07-24 15:25:05 +02:00
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2014-12-23 22:09:48 -08:00
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2007-02-05 16:12:44 -08:00
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2017-02-28 16:44:16 -05:00
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2007-02-05 16:12:44 -08:00
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