Starting the kernel client with cephx disabled and then enabling cephx
and restarting userspace daemons can result in a crash:
[262671.478162] BUG: unable to handle kernel paging request at ffffebe000000000
[262671.531460] IP: [<ffffffff811cd04a>] kfree+0x5a/0x130
[262671.584334] PGD 0
[262671.635847] Oops: 0000 [#1] SMP
[262672.055841] CPU: 22 PID: 2961272 Comm: kworker/22:2 Not tainted 4.2.0-34-generic #39~14.04.1-Ubuntu
[262672.162338] Hardware name: Dell Inc. PowerEdge R720/068CDY, BIOS 2.4.3 07/09/2014
[262672.268937] Workqueue: ceph-msgr con_work [libceph]
[262672.322290] task: ffff88081c2d0dc0 ti: ffff880149ae8000 task.ti: ffff880149ae8000
[262672.428330] RIP: 0010:[<ffffffff811cd04a>] [<ffffffff811cd04a>] kfree+0x5a/0x130
[262672.535880] RSP: 0018:ffff880149aeba58 EFLAGS: 00010286
[262672.589486] RAX: 000001e000000000 RBX: 0000000000000012 RCX: ffff8807e7461018
[262672.695980] RDX: 000077ff80000000 RSI: ffff88081af2be04 RDI: 0000000000000012
[262672.803668] RBP: ffff880149aeba78 R08: 0000000000000000 R09: 0000000000000000
[262672.912299] R10: ffffebe000000000 R11: ffff880819a60e78 R12: ffff8800aec8df40
[262673.021769] R13: ffffffffc035f70f R14: ffff8807e5b138e0 R15: ffff880da9785840
[262673.131722] FS: 0000000000000000(0000) GS:ffff88081fac0000(0000) knlGS:0000000000000000
[262673.245377] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[262673.303281] CR2: ffffebe000000000 CR3: 0000000001c0d000 CR4: 00000000001406e0
[262673.417556] Stack:
[262673.472943] ffff880149aeba88 ffff88081af2be04 ffff8800aec8df40 ffff88081af2be04
[262673.583767] ffff880149aeba98 ffffffffc035f70f ffff880149aebac8 ffff8800aec8df00
[262673.694546] ffff880149aebac8 ffffffffc035c89e ffff8807e5b138e0 ffff8805b047f800
[262673.805230] Call Trace:
[262673.859116] [<ffffffffc035f70f>] ceph_x_destroy_authorizer+0x1f/0x50 [libceph]
[262673.968705] [<ffffffffc035c89e>] ceph_auth_destroy_authorizer+0x3e/0x60 [libceph]
[262674.078852] [<ffffffffc0352805>] put_osd+0x45/0x80 [libceph]
[262674.134249] [<ffffffffc035290e>] remove_osd+0xae/0x140 [libceph]
[262674.189124] [<ffffffffc0352aa3>] __reset_osd+0x103/0x150 [libceph]
[262674.243749] [<ffffffffc0354703>] kick_requests+0x223/0x460 [libceph]
[262674.297485] [<ffffffffc03559e2>] ceph_osdc_handle_map+0x282/0x5e0 [libceph]
[262674.350813] [<ffffffffc035022e>] dispatch+0x4e/0x720 [libceph]
[262674.403312] [<ffffffffc034bd91>] try_read+0x3d1/0x1090 [libceph]
[262674.454712] [<ffffffff810ab7c2>] ? dequeue_entity+0x152/0x690
[262674.505096] [<ffffffffc034cb1b>] con_work+0xcb/0x1300 [libceph]
[262674.555104] [<ffffffff8108fb3e>] process_one_work+0x14e/0x3d0
[262674.604072] [<ffffffff810901ea>] worker_thread+0x11a/0x470
[262674.652187] [<ffffffff810900d0>] ? rescuer_thread+0x310/0x310
[262674.699022] [<ffffffff810957a2>] kthread+0xd2/0xf0
[262674.744494] [<ffffffff810956d0>] ? kthread_create_on_node+0x1c0/0x1c0
[262674.789543] [<ffffffff817bd81f>] ret_from_fork+0x3f/0x70
[262674.834094] [<ffffffff810956d0>] ? kthread_create_on_node+0x1c0/0x1c0
What happens is the following:
(1) new MON session is established
(2) old "none" ac is destroyed
(3) new "cephx" ac is constructed
...
(4) old OSD session (w/ "none" authorizer) is put
ceph_auth_destroy_authorizer(ac, osd->o_auth.authorizer)
osd->o_auth.authorizer in the "none" case is just a bare pointer into
ac, which contains a single static copy for all services. By the time
we get to (4), "none" ac, freed in (2), is long gone. On top of that,
a new vtable installed in (3) points us at ceph_x_destroy_authorizer(),
so we end up trying to destroy a "none" authorizer with a "cephx"
destructor operating on invalid memory!
To fix this, decouple authorizer destruction from ac and do away with
a single static "none" authorizer by making a copy for each OSD or MDS
session. Authorizers themselves are independent of ac and so there is
no reason for destroy_authorizer() to be an ac op. Make it an op on
the authorizer itself by turning ceph_authorizer into a real struct.
Fixes: http://tracker.ceph.com/issues/15447
Reported-by: Alan Zhang <alan.zhang@linux.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Reviewed-by: Sage Weil <sage@redhat.com>
If hook spi_flash_read is implemented the fast flash read feature
is enabled for all devices attached to the respective master.
In most cases there is just one flash chip, however there are also
devices with more than one flash chip, namely some WiFi routers.
Then the fast flash read feature can be used for the first chip only.
OpenWRT implemented an own handling of this case, using controller_data
element of spi_device to hold the information whether fast flash read
can be used for a device.
This patch adds hook flash_read_supported to spi_master which is
used to extend spi_flash_read_supported() by checking whether the
fast flash read feature can be used for a specific spi_device.
If the hook is not implemented the default behavior is to allow
fast flash read for all devices (if spi_flash_read is implemented).
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
d894ba18d4 ("soreuseport: fix ordering for mixed v4/v6 sockets")
was merged as a bug fix to the net tree. Two conflicting changes
were committed to net-next before the above fix was merged back to
net-next:
ca065d0cf8 ("udp: no longer use SLAB_DESTROY_BY_RCU")
3b24d854cb ("tcp/dccp: do not touch listener sk_refcnt under synflood")
These changes switched the datastructure used for TCP and UDP sockets
from hlist_nulls to hlist. This patch applies the necessary parts
of the net tree fix to net-next which were not automatic as part of the
merge.
Fixes: 1602f49b58 ("Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net")
Signed-off-by: Craig Gallek <kraig@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Valdis reported tons of stack dumps caused by WARN_ON() in
sock_owned_by_user()
This test needs to be relaxed if/when lockdep disables itself.
Note that other lockdep_sock_is_held() callers are all from
rcu_dereference_protected() sections which already are disabled
if/when lockdep has been disabled.
Fixes: fafc4e1ea1 ("sock: tigthen lockdep checks for sock_owned_by_user")
Reported-by: Valdis Kletnieks <Valdis.Kletnieks@vt.edu>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
dev_pm_opp_set_sharing_cpus() doesn't do any DT specific stuff and its
declarations are added within the CONFIG_OF ifdef by mistake. Take them
out of that.
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Reviewed-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Simon Horman says:
====================
IPVS Updates for v4.7
please consider these enhancements to the IPVS. They allow SIP connections
originating from real-servers to be load balanced by the SIP psersitence
engine as is already implemented in the other direction. And for better one
packet scheduling (OPS) performance.
====================
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
When using a device is read/write mode, vb2 does not handle properly the
first select/poll operation.
The reason for this, is that when this code has been refactored, some of
the operations have changed their order, and now fileio emulator is not
started.
The reintroduced check to the core is enabled by a quirk flag, that
avoids this check by other subsystems like DVB.
Fixes: 49d8ab9fea ("media] media: videobuf2: Separate vb2_poll()")
Reported-by: Dimitrios Katsaros <patcherwork@gmail.com>
Cc: Junghak Sung <jh1009.sung@samsung.com>
Cc: <stable@vger.kernel.org> # for v4.5 and up
Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
The VSync polarity was negative instead of positive for the 4k CEA formats.
I probably copy-and-pasted these from the DMT 4k format, which does have a
negative VSync polarity.
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Reported-by: Martin Bugge <marbugge@cisco.com>
Cc: <stable@vger.kernel.org> # for v4.1 and up
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
The complete common architectural and micro-architectural
event number structure is filtered based on PMCEIDn_EL0 and
exposed to /sys using is_visibile function pointer in events
attribute_group.
To filter the events in is_visible function, pmceid based bitmap
is stored in arm_pmu structure and the id field from
perf_pmu_events_attr is used to check against the bitmap.
The function which derives event bitmap from PMCEIDn_EL0 is
executed in the cpus, which has the pmu being initialized,
for heterogeneous pmu support.
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Ashok Kumar <ashoks@broadcom.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
As earlier commit removed accessed to the hash from other files we can
also make it static.
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
We only allow rehash in init namespace, so we only use
init_ns.generation. And even if we would allow it, it makes no sense
as the conntrack locks are global; any ongoing rehash prevents insert/
delete.
So make this private to nf_conntrack_core instead.
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Most of what is marked as 'experimental' has been around for years. Time
to drop that annotation.
The only remaining 'experimental' bits of the API are the debug ioctls
and structs: these should remain experimental since the only application
that should use this is v4l2-dbg.
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
Move the better constructs/comments from i915_gem_stolen.c to
early-quirks.c and increase readability in preparation of only
having one set of functions.
- intel_stolen_base -> gen3_stolen_base
- use phys_addr_t instead of u32 for address for future proofing
v2:
- Print the invalid register values (Chris)
(Omitting the register prefix as it's visible from backtrace.)
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Acked-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
There are no users of rtctimer left. Remove its code as this is the
in-kernel user of the legacy PC RTC driver that will hopefully be removed
at some point.
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Merge necessary new clocks from Sylwester (used by new board) and add support
for Exynos3250-based Artik5 board.
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Merge tag 'samsung-dt-exynos3250-artik5-4.7' of git://git.kernel.org/pub/scm/linux/kernel/git/krzk/linux into next/dt
Merge "Topic branch for Device Tree changes for Exynos 3250 for v4.7" from Krzysztof Kozlowski:
Merge necessary new clocks from Sylwester (used by new board) and add support
for Exynos3250-based Artik5 board.
* tag 'samsung-dt-exynos3250-artik5-4.7' of git://git.kernel.org/pub/scm/linux/kernel/git/krzk/linux:
ARM: dts: exynos: Add MSHC2 DT node for SD card for exynos3250-artik5-eval board
ARM: dts: exynos: Add exynos3250-artik5 dtsi file for ARTIK5 module
ARM: dts: exynos: Add MSHC2 DT node for Exynos3250 SoC
ARM: dts: exynos: Add UART2 DT node for Exynos3250 SoC
ARM: dts: exynos: Add initial gpio setting of MMC2 device for exynos3250-monk
ARM: dts: exynos: Add initial pin configuration for exynos3250-rinato
clk: samsung: exynos3250: Add MMC2 clock
clk: samsung: exynos3250: Add UART2 clock
dt-bindings: Add the clock id of UART2 and MMC2 for Exynos3250
This patch introduces kexec support for mlx5.
When switching kernels, kexec() calls shutdown, which unloads
the driver and cleans its resources.
In addition, remove unregister netdev from shutdown flow. This will
allow a clean shutdown, even if some netdev clients did not release their
reference from this netdev. Releasing The HW resources only is enough as
the kernel is shutting down
Signed-off-by: Majd Dibbiny <majd@mellanox.com>
Signed-off-by: Tariq Toukan <tariqt@mellanox.com>
Signed-off-by: Haggai Abramovsky <hagaya@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Set and report vport MTU rather than physical MTU,
Driver will set both vport and physical port mtu and will
rely on the query of vport mtu.
SRIOV VFs have to report their MTU to their vport manager (PF),
and this will allow them to work with any MTU they need
without failing the request.
Also for some cases where the PF is not a port owner, PF can
work with MTU less than the physical port mtu if set physical
port mtu didn't take effect.
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
For set/query MTU port firmware commands the MTU field
is 16 bits, here I changed all the "int mtu" parameters
of the functions wrapping those firmware commands to be u16.
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Linux TCP stack painfully segments all TSO/GSO packets before retransmits.
This was fine back in the days when TSO/GSO were emerging, with their
bugs, but we believe the dark age is over.
Keeping big packets in write queues, but also in stack traversal
has a lot of benefits.
- Less memory overhead, because write queues have less skbs
- Less cpu overhead at ACK processing.
- Better SACK processing, as lot of studies mentioned how
awful linux was at this ;)
- Less cpu overhead to send the rtx packets
(IP stack traversal, netfilter traversal, drivers...)
- Better latencies in presence of losses.
- Smaller spikes in fq like packet schedulers, as retransmits
are not constrained by TCP Small Queues.
1 % packet losses are common today, and at 100Gbit speeds, this
translates to ~80,000 losses per second.
Losses are often correlated, and we see many retransmit events
leading to 1-MSS train of packets, at the time hosts are already
under stress.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
I accidentally forgot some MACSEC_ prefixes in if_macsec.h.
Fixes: dece8d2b78 ("uapi: add MACsec bits")
Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
When using switchdev deferred operation (SWITCHDEV_F_DEFER), the operation
is executed in different context and the application doesn't have any way
to get the operation real status.
Adding a completion callback fixes that. This patch adds fields to
switchdev_attr and switchdev_obj "complete_priv" field which is used by
the "complete" callback.
Application can set a complete function which will be called once the
operation executed.
Signed-off-by: Elad Raz <eladr@mellanox.com>
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Reviewed-by: Ido Schimmel <idosch@mellanox.com>
Acked-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Currently when filesystem needs to make sure data is on permanent
storage before committing a transaction it adds inode to transaction's
inode list. During transaction commit, jbd2 writes back all dirty
buffers that have allocated underlying blocks and waits for the IO to
finish. However when doing writeback for delayed allocated data, we
allocate blocks and immediately submit the data. Thus asking jbd2 to
write dirty pages just unnecessarily adds more work to jbd2 possibly
writing back other redirtied blocks.
Add support to jbd2 to allow filesystem to ask jbd2 to only wait for
outstanding data writes before committing a transaction and thus avoid
unnecessary writes.
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Pablo Neira Ayuso says:
====================
Netfilter updates for net-next
The following patchset contains Netfilter updates for your net-next
tree, mostly from Florian Westphal to sort out the lack of sufficient
validation in x_tables and connlabel preparation patches to add
nf_tables support. They are:
1) Ensure we don't go over the ruleset blob boundaries in
mark_source_chains().
2) Validate that target jumps land on an existing xt_entry. This extra
sanitization comes with a performance penalty when loading the ruleset.
3) Introduce xt_check_entry_offsets() and use it from {arp,ip,ip6}tables.
4) Get rid of the smallish check_entry() functions in {arp,ip,ip6}tables.
5) Make sure the minimal possible target size in x_tables.
6) Similar to #3, add xt_compat_check_entry_offsets() for compat code.
7) Check that standard target size is valid.
8) More sanitization to ensure that the target_offset field is correct.
9) Add xt_check_entry_match() to validate that matches are well-formed.
10-12) Three patch to reduce the number of parameters in
translate_compat_table() for {arp,ip,ip6}tables by using a container
structure.
13) No need to return value from xt_compat_match_from_user(), so make
it void.
14) Consolidate translate_table() so it can be used by compat code too.
15) Remove obsolete check for compat code, so we keep consistent with
what was already removed in the native layout code (back in 2007).
16) Get rid of target jump validation from mark_source_chains(),
obsoleted by #2.
17) Introduce xt_copy_counters_from_user() to consolidate counter
copying, and use it from {arp,ip,ip6}tables.
18,22) Get rid of unnecessary explicit inlining in ctnetlink for dump
functions.
19) Move nf_connlabel_match() to xt_connlabel.
20) Skip event notification if connlabel did not change.
21) Update of nf_connlabels_get() to make the upcoming nft connlabel
support easier.
23) Remove spinlock to read protocol state field in conntrack.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>
Pull thermal fixes from Eduardo Valentin:
"Specifics in this pull request:
- Fixes in mediatek and OF thermal drivers
- Fixes in power_allocator governor
- More fixes of unsigned to int type change in thermal_core.c.
These change have been CI tested using KernelCI bot. \o/"
* 'fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/evalenti/linux-soc-thermal:
thermal: fix Mediatek thermal controller build
thermal: consistently use int for trip temp
thermal: fix mtk_thermal build dependency
thermal: minor mtk_thermal.c cleanups
thermal: power_allocator: req_range multiplication should be a 64 bit type
thermal: of: add __init attribute
With this function, nla_data() is aligned on a 64-bit area.
Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
nla_data() is now aligned on a 64-bit area.
Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
nla_data() is now aligned on a 64-bit area.
In fact, there is no user of this function.
Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
nla_data() is now aligned on a 64-bit area.
The temporary function nla_put_be64_32bit() is removed in this patch.
Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
nla_data() is now aligned on a 64-bit area.
A temporary version (nla_put_be64_32bit()) is added for nla_put_net64().
This function is removed in the next patch.
Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
nla_data() is now aligned on a 64-bit area.
Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Conflicts were two cases of simple overlapping changes,
nothing serious.
In the UDP case, we need to add a hlist_add_tail_rcu()
to linux/rculist.h, because we've moved UDP socket handling
away from using nulls lists.
Signed-off-by: David S. Miller <davem@davemloft.net>
Here is one patch to wire up the preadv/pwritev system calls in the
generic system call table, which is required for all architectures
that were merged in the last few years, including arm64.
Usually these get merged along with the syscall implementation
or one of the architecture trees, but this time that did not
happen.
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Merge tag 'asm-generic-4.6' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/asm-generic
Pull asm-generic update from Arnd Bergmann:
"Here is one patch to wire up the preadv/pwritev system calls in the
generic system call table, which is required for all architectures
that were merged in the last few years, including arm64.
Usually these get merged along with the syscall implementation or one
of the architecture trees, but this time that did not happen.
Andre and Christoph both sent a version of this patch, I picked the
one I got first"
* tag 'asm-generic-4.6' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/asm-generic:
generic syscalls: wire up preadv2 and pwritev2 syscalls
Add a new rotation matrix sysfs attribute compliant with IIO core
mounting matrix API.
Matrix is retrieved from "in_anglvel_mount_matrix" and
"in_accel_mount_matrix" sysfs attributes. It is declared into mpu6050 DTS
entry as a "mount-matrix" property.
Old interface is kept for backward userspace compatibility and may be
retrieved from legacy platform_data mechanism only.
Signed-off-by: Gregor Boirie <gregor.boirie@parrot.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
Expose a rotation matrix to indicate userspace the chip orientation with
respect to the overall hardware system.
Matrix is retrieved from "in_mount_matrix". It is declared into ak8975 DTS
entry as a "mount-matrix" property.
Signed-off-by: Gregor Boirie <gregor.boirie@parrot.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
Expose a rotation matrix to indicate userspace the chip placement with
respect to the overall hardware system. This is needed to adjust
coordinates sampled from a sensor chip when its position deviates from the
main hardware system.
Final coordinates computation is delegated to userspace since:
* computation may involve floating point arithmetics ;
* it allows an application to combine adjustments with arbitrary
transformations.
This 3 dimentional space rotation matrix is expressed as 3x3 array of
strings to support floating point numbers. It may be retrieved from a
"[<dir>_][<type>_]mount_matrix" sysfs attribute file. It is declared into a
device / driver specific DTS property or platform data.
Signed-off-by: Gregor Boirie <gregor.boirie@parrot.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
These new syscalls are implemented as generic code, so enable them for
architectures like arm64 which use the generic syscall table.
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Pull locking fixes from Ingo Molnar:
"Misc fixes:
pvqspinlocks:
- an instrumentation fix
futexes:
- preempt-count vs pagefault_disable decouple corner case fix
- futex requeue plist race window fix
- futex UNLOCK_PI transaction fix for a corner case"
* 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
asm-generic/futex: Re-enable preemption in futex_atomic_cmpxchg_inatomic()
futex: Acknowledge a new waiter in counter before plist
futex: Handle unlock_pi race gracefully
locking/pvqspinlock: Fix division by zero in qstat_read()
Ticks can happen while the CPU is in dynticks-idle or dynticks-singletask
mode. In fact "nohz" or "dynticks" only mean that we exit the periodic
mode and we try to minimize the ticks as much as possible. The nohz
subsystem uses a confusing terminology with the internal state
"ts->tick_stopped" which is also available through its public interface
with tick_nohz_tick_stopped(). This is a misnomer as the tick is instead
reduced with the best effort rather than stopped. In the best case the
tick can indeed be actually stopped but there is no guarantee about that.
If a timer needs to fire one second later, a tick will fire while the
CPU is in nohz mode and this is a very common scenario.
Now this confusion happens to be a problem with CPU load updates:
cpu_load_update_active() doesn't handle nohz ticks correctly because it
assumes that ticks are completely stopped in nohz mode and that
cpu_load_update_active() can't be called in dynticks mode. When that
happens, the whole previous tickless load is ignored and the function
just records the load for the current tick, ignoring potentially long
idle periods behind.
In order to solve this, we could account the current load for the
previous nohz time but there is a risk that we account the load of a
task that got freshly enqueued for the whole nohz period.
So instead, lets record the dynticks load on nohz frame entry so we know
what to record in case of nohz ticks, then use this record to account
the tickless load on nohz ticks and nohz frame end.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Byungchul Park <byungchul.park@lge.com>
Cc: Chris Metcalf <cmetcalf@ezchip.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Luiz Capitulino <lcapitulino@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul E . McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1460555812-25375-3-git-send-email-fweisbec@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The CPU load update related functions have a weak naming convention
currently, starting with update_cpu_load_*() which isn't ideal as
"update" is a very generic concept.
Since two of these functions are public already (and a third is to come)
that's enough to introduce a more conventional naming scheme. So let's
do the following rename instead:
update_cpu_load_*() -> cpu_load_update_*()
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Byungchul Park <byungchul.park@lge.com>
Cc: Chris Metcalf <cmetcalf@ezchip.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Luiz Capitulino <lcapitulino@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul E . McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1460555812-25375-2-git-send-email-fweisbec@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This patch introduces 'write_backward' bit to perf_event_attr, which
controls the direction of a ring buffer. After set, the corresponding
ring buffer is written from end to beginning. This feature is design to
support reading from overwritable ring buffer.
Ring buffer can be created by mapping a perf event fd. Kernel puts event
records into ring buffer, user tooling like perf fetch them from
address returned by mmap(). To prevent racing between kernel and tooling,
they communicate to each other through 'head' and 'tail' pointers.
Kernel maintains 'head' pointer, points it to the next free area (tail
of the last record). Tooling maintains 'tail' pointer, points it to the
tail of last consumed record (record has already been fetched). Kernel
determines the available space in a ring buffer using these two
pointers to avoid overwrite unfetched records.
By mapping without 'PROT_WRITE', an overwritable ring buffer is created.
Different from normal ring buffer, tooling is unable to maintain 'tail'
pointer because writing is forbidden. Therefore, for this type of ring
buffers, kernel overwrite old records unconditionally, works like flight
recorder. This feature would be useful if reading from overwritable ring
buffer were as easy as reading from normal ring buffer. However,
there's an obscure problem.
The following figure demonstrates a full overwritable ring buffer. In
this figure, the 'head' pointer points to the end of last record, and a
long record 'E' is pending. For a normal ring buffer, a 'tail' pointer
would have pointed to position (X), so kernel knows there's no more
space in the ring buffer. However, for an overwritable ring buffer,
kernel ignore the 'tail' pointer.
(X) head
. |
. V
+------+-------+----------+------+---+
|A....A|B.....B|C........C|D....D| |
+------+-------+----------+------+---+
Record 'A' is overwritten by event 'E':
head
|
V
+--+---+-------+----------+------+---+
|.E|..A|B.....B|C........C|D....D|E..|
+--+---+-------+----------+------+---+
Now tooling decides to read from this ring buffer. However, none of these
two natural positions, 'head' and the start of this ring buffer, are
pointing to the head of a record. Even the full ring buffer can be
accessed by tooling, it is unable to find a position to start decoding.
The first attempt tries to solve this problem AFAIK can be found from
[1]. It makes kernel to maintain 'tail' pointer: updates it when ring
buffer is half full. However, this approach introduces overhead to
fast path. Test result shows a 1% overhead [2]. In addition, this method
utilizes no more tham 50% records.
Another attempt can be found from [3], which allows putting the size of
an event at the end of each record. This approach allows tooling to find
records in a backward manner from 'head' pointer by reading size of a
record from its tail. However, because of alignment requirement, it
needs 8 bytes to record the size of a record, which is a huge waste. Its
performance is also not good, because more data need to be written.
This approach also introduces some extra branch instructions to fast
path.
'write_backward' is a better solution to this problem.
Following figure demonstrates the state of the overwritable ring buffer
when 'write_backward' is set before overwriting:
head
|
V
+---+------+----------+-------+------+
| |D....D|C........C|B.....B|A....A|
+---+------+----------+-------+------+
and after overwriting:
head
|
V
+---+------+----------+-------+---+--+
|..E|D....D|C........C|B.....B|A..|E.|
+---+------+----------+-------+---+--+
In each situation, 'head' points to the beginning of the newest record.
From this record, tooling can iterate over the full ring buffer and fetch
records one by one.
The only limitation that needs to be considered is back-to-back reading.
Due to the non-deterministic of user programs, it is impossible to ensure
the ring buffer keeps stable during reading. Consider an extreme situation:
tooling is scheduled out after reading record 'D', then a burst of events
come, eat up the whole ring buffer (one or multiple rounds). When the
tooling process comes back, reading after 'D' is incorrect now.
To prevent this problem, we need to find a way to ensure the ring buffer
is stable during reading. ioctl(PERF_EVENT_IOC_PAUSE_OUTPUT) is
suggested because its overhead is lower than
ioctl(PERF_EVENT_IOC_ENABLE).
By carefully verifying 'header' pointer, reader can avoid pausing the
ring-buffer. For example:
/* A union of all possible events */
union perf_event event;
p = head = perf_mmap__read_head();
while (true) {
/* copy header of next event */
fetch(&event.header, p, sizeof(event.header));
/* read 'head' pointer */
head = perf_mmap__read_head();
/* check overwritten: is the header good? */
if (!verify(sizeof(event.header), p, head))
break;
/* copy the whole event */
fetch(&event, p, event.header.size);
/* read 'head' pointer again */
head = perf_mmap__read_head();
/* is the whole event good? */
if (!verify(event.header.size, p, head))
break;
p += event.header.size;
}
However, the overhead is high because:
a) In-place decoding is not safe.
Copying-verifying-decoding is required.
b) Fetching 'head' pointer requires additional synchronization.
(From Alexei Starovoitov:
Even when this trick works, pause is needed for more than stability of
reading. When we collect the events into overwrite buffer we're waiting
for some other trigger (like all cpu utilization spike or just one cpu
running and all others are idle) and when it happens the buffer has
valuable info from the past. At this point new events are no longer
interesting and buffer should be paused, events read and unpaused until
next trigger comes.)
This patch utilizes event's default overflow_handler introduced
previously. perf_event_output_backward() is created as the default
overflow handler for backward ring buffers. To avoid extra overhead to
fast path, original perf_event_output() becomes __perf_event_output()
and marked '__always_inline'. In theory, there's no extra overhead
introduced to fast path.
Performance testing:
Calling 3000000 times of 'close(-1)', use gettimeofday() to check
duration. Use 'perf record -o /dev/null -e raw_syscalls:*' to capture
system calls. In ns.
Testing environment:
CPU : Intel(R) Core(TM) i7-4790 CPU @ 3.60GHz
Kernel : v4.5.0
MEAN STDVAR
BASE 800214.950 2853.083
PRE1 2253846.700 9997.014
PRE2 2257495.540 8516.293
POST 2250896.100 8933.921
Where 'BASE' is pure performance without capturing. 'PRE1' is test
result of pure 'v4.5.0' kernel. 'PRE2' is test result before this
patch. 'POST' is test result after this patch. See [4] for the detailed
experimental setup.
Considering the stdvar, this patch doesn't introduce performance
overhead to the fast path.
[1] http://lkml.iu.edu/hypermail/linux/kernel/1304.1/04584.html
[2] http://lkml.iu.edu/hypermail/linux/kernel/1307.1/00535.html
[3] http://lkml.iu.edu/hypermail/linux/kernel/1512.0/01265.html
[4] http://lkml.kernel.org/g/56F89DCD.1040202@huawei.com
Signed-off-by: Wang Nan <wangnan0@huawei.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Cc: <acme@kernel.org>
Cc: <pi3orama@163.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Brendan Gregg <brendan.d.gregg@gmail.com>
Cc: He Kuang <hekuang@huawei.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Cc: Zefan Li <lizefan@huawei.com>
Link: http://lkml.kernel.org/r/1459865478-53413-1-git-send-email-wangnan0@huawei.com
[ Fixed the changelog some more. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
