The current mutex-based funnel-locking approach used by expedited grace
periods is subject to severe unfairness. The problem arises when a
few tasks, making a path from leaves to root, all wake up before other
tasks do. A new task can then follow this path all the way to the root,
which needlessly delays tasks whose grace period is done, but who do
not happen to acquire the lock quickly enough.
This commit avoids this problem by maintaining per-rcu_node wait queues,
along with a per-rcu_node counter that tracks the latest grace period
sought by an earlier task to visit this node. If that grace period
would satisfy the current task, instead of proceeding up the tree,
it waits on the current rcu_node structure using a pair of wait queues
provided for that purpose. This decouples awakening of old tasks from
the arrival of new tasks.
If the wakeups prove to be a bottleneck, additional kthreads can be
brought to bear for that purpose.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
The cpu_online() function can return values other than 0 and 1, which
can result in subscript overflow when applied to a two-element array.
This commit allows for this behavior by using "!!" on the return value
from cpu_online() when used as a subscript.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Commit #cdacbe1f91 ("rcu: Add fastpath bypassing funnel locking")
turns out to be a pessimization at high load because it forces a tree
full of tasks to wait for an expedited grace period that they probably
do not need. This commit therefore removes this optimization.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
This commit brings the synchronize_rcu_expedited() function's header
comment into line with the new implementation.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Although cond_resched_rcu_qs() supplies quiescent states to all flavors
of normal RCU grace periods, it does nothing for expedited RCU-sched
grace periods. This commit therefore adds a check for a need for a
quiescent state from the current CPU by an expedited RCU-sched grace
period, and invokes rcu_sched_qs() to supply that quiescent state if so.
Note that the check is racy in that we might be migrated to some other
CPU just after checking the per-CPU variable. This is OK because the
act of migration will do a context switch, which will supply the needed
quiescent state. The only downside is that we might do an unnecessary
call to rcu_sched_qs(), but the probability is low and the overhead
is small.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Currently, synchronize_sched_expedited_wait() simply sets the ndetected
variable to the rcu_print_task_exp_stall() return value. This means
that if the last rcu_node structure has no stalled tasks, record of
any stalled tasks in previous rcu_node structures is lost, which can
in turn result in failure to dump out the blocking rcu_node structures.
Or could, had the test been correct.
This commit therefore adds the return value of rcu_print_task_exp_stall()
to ndetected and corrects the later test for ndetected.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Currently, sync_sched_exp_handler() will force a reschedule unless
this CPU has already checked in or unless a reschedule has already
been called for. This is clearly wasteful if sync_sched_exp_handler()
interrupted an idle CPU, so this commit immediately reports the
quiescent state in that case.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Commit 4dffbfc48d ("arm64/efi: mark UEFI reserved regions as
MEMBLOCK_NOMAP") updated the mapping logic of both the RuntimeServices
regions as well as the kernel's copy of the UEFI memory map to set the
MEMBLOCK_NOMAP flag, which causes these regions to be omitted from the
kernel direct mapping, and from being covered by a struct page.
For the RuntimeServices regions, this is an obvious win, since the contents
of these regions have significance to the firmware executable code itself,
and are mapped in the EFI page tables using attributes that are described in
the UEFI memory map, and which may differ from the attributes we use for
mapping system RAM. It also prevents the contents from being modified
inadvertently, since the EFI page tables are only live during runtime
service invocations.
None of these concerns apply to the allocation that covers the UEFI memory
map, since it is entirely owned by the kernel. Setting the MEMBLOCK_NOMAP on
the region did allow us to use ioremap_cache() to map it both on arm64 and
on ARM, since the latter does not allow ioremap_cache() to be used on
regions that are covered by a struct page.
The ioremap_cache() on ARM restriction will be lifted in the v4.7 timeframe,
but in the mean time, it has been reported that commit 4dffbfc48d causes
a regression on 64k granule kernels. This is due to the fact that, given
the 64 KB page size, the region that we end up removing from the kernel
direct mapping is rounded up to 64 KB, and this 64 KB page frame may be
shared with the initrd when booting via GRUB (which does not align its
EFI_LOADER_DATA allocations to 64 KB like the stub does). This will crash
the kernel as soon as it tries to access the initrd.
Since the issue is specific to arm64, revert back to memblock_reserve()'ing
the UEFI memory map when running on arm64. This is a temporary fix for v4.5
and v4.6, and will be superseded in the v4.7 timeframe when we will be able
to move back to memblock_reserve() unconditionally.
Fixes: 4dffbfc48d ("arm64/efi: mark UEFI reserved regions as MEMBLOCK_NOMAP")
Reported-by: Mark Salter <msalter@redhat.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Acked-by: Will Deacon <will.deacon@arm.com>
Cc: Leif Lindholm <leif.lindholm@linaro.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Jeremy Linton <jeremy.linton@arm.com>
Cc: Mark Langsdorf <mlangsdo@redhat.com>
Cc: <stable@vger.kernel.org> # v4.5
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
Although call_rcu()'s fastpath works just fine on an idle CPU,
some branches of the slowpath invoke the scheduler, which uses
RCU. Therefore, this commit emphasizes the fact that call_rcu()
must not be invoked from an idle CPU.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
This commit uses colors to obscure the quick-quiz answers, thus getting
rid of the .htmlx file. Use your mouse to select the answer in order
to see the text. Alternatively, use your favorite scripting language
to remove all occurences of "<font color="ffffff">" from the file.
Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
This commit removes a cutesy cartoon and also a diagram that can
just as easily be represented by text.
Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
There is already a blanket statement about no member of RCU's API
being legal from an offline CPU, but add an explicit note where it
states that it is illegal to invoke call_rcu() from an NMI handler.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
This commit adds a Quick Quiz whose answer explains why the compiler
code reordering enabled by CONFIG_PREEMPT=n's empty rcu_read_lock()
and rcu_read_unlock() functions does not hinder RCU's ability to figure
out which RCU read-side critical sections have completed and not.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
This commit records RCU's responsibility to avoid degrading latencies
of CPUs running tight loops within properly configured workloads,
both in kernel and in userspace.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
In the chapter 'analogy with reader-writer locking', the sample
code uses spinlock_t in reader-writer case. Just correct it so
that we can read the document easily.
Signed-off-by: Yao Dongdong <yaodongdong@huawei.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
This commit consolidates a couple definitions and several calls for
single-shot ftrace-buffer dumping.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Drop #address-cells and #size-cells, which are not required by the
gpio-keys binding documentation, as button sub-nodes are not devices.
Rename sub-nodes to avoid new dtc unit address warnings when copied.
While at it, adopt the dashes convention for the node name.
Reported-by: Julien Chauveau <chauveau.julien@gmail.com>
Signed-off-by: Andreas Färber <afaerber@suse.de>
Reviewed-by: Javier Martinez Canillas <javier@osg.samsung.com>
Reviewed-by: Julien Chauveau <chauveau.julien@gmail.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
The device can now easily be derived from the interface.
Stop leaving a private copy.
Signed-off-by: Oliver Neukum <ONeukum@suse.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
The device can now easily be derived from the interface.
Stop leaving a private copy.
Signed-off-by: Oliver Neukum <oneukum@suse.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
The device can now easily be derived from the interface.
Stop leaving a private copy.
Signed-off-by: Oliver Neukum <oneukum@suse.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
The device can now easily be derived from the interface.
Stop leaving a private copy.
Signed-off-by: Oliver Neukum <ONeukum@suse.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
This is for fixing checkpatch.pl warning about
"Alignment should match open parenthesis" but if that is
fixed, code line is over 80 characters.
I think "ch->ch_rqueue + tail + i" could be declared once in
the begining of loop.
Signed-off-by: Daeseok Youn <daeseok.youn@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
It doesn't need to save major number with variable.
And there are no use of these variables(dgnc_serial_major and
dgnc_transparent_print_major)
Signed-off-by: Daeseok Youn <daeseok.youn@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The use of poll_count is a vestige from long-ago testing, which is no
longer needed. It is removed by this patch.
Signed-off-by: Tim Sell <Timothy.Sell@unisys.com>
Signed-off-by: David Kershner <david.kershner@unisys.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The gtco driver expects at least one valid endpoint. If given malicious
descriptors that specify 0 for the number of endpoints, it will crash in
the probe function. Ensure there is at least one endpoint on the interface
before using it.
Also let's fix a minor coding style issue.
The full correct report of this issue can be found in the public
Red Hat Bugzilla:
https://bugzilla.redhat.com/show_bug.cgi?id=1283385
Reported-by: Ralf Spenneberg <ralf@spenneberg.net>
Signed-off-by: Vladis Dronov <vdronov@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
We don't really need linux specific headers anymore so move
NUM_CACHEPAGES macro to libcfs_prim.h.
Signed-off-by: James Simmons <uja.ornl@gmail.com>
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-6245
Reviewed-on: http://review.whamcloud.com/13841
Reviewed-by: frank zago <fzago@cray.com>
Reviewed-by: Dmitry Eremin <dmitry.eremin@intel.com>
Reviewed-by: John L. Hammond <john.hammond@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Another abstraction that is not needed.
Signed-off-by: James Simmons <uja.ornl@gmail.com>
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-6245
Reviewed-on: http://review.whamcloud.com/13841
Reviewed-by: frank zago <fzago@cray.com>
Reviewed-by: Dmitry Eremin <dmitry.eremin@intel.com>
Reviewed-by: John L. Hammond <john.hammond@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Just use the index field directly for struct page.
Signed-off-by: James Simmons <uja.ornl@gmail.com>
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-6245
Reviewed-on: http://review.whamcloud.com/13841
Reviewed-by: frank zago <fzago@cray.com>
Reviewed-by: Dmitry Eremin <dmitry.eremin@intel.com>
Reviewed-by: John L. Hammond <john.hammond@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Long ago libcfs_prim.h was used for userland code which is why
memory_pressure_*() handling is in both libcfs_prim.h and
linux-mem.h headers. So lets just move the memory_pressure_*()
to libcfs_prim.h.
Signed-off-by: James Simmons <uja.ornl@gmail.com>
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-6245
Reviewed-on: http://review.whamcloud.com/13841
Reviewed-by: frank zago <fzago@cray.com>
Reviewed-by: Dmitry Eremin <dmitry.eremin@intel.com>
Reviewed-by: John L. Hammond <john.hammond@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Only lustre client uses add_wait_queue_exclusive_head() so move
it from libcfs layer to lustre_lib.h where it is needed.
Signed-off-by: James Simmons <uja.ornl@gmail.com>
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-6245
Reviewed-on: http://review.whamcloud.com/13874
Reviewed-by: Dmitry Eremin <dmitry.eremin@intel.com>
Reviewed-by: John L. Hammond <john.hammond@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Commit 55cd48c821 ("net: fec: stop the "rcv is not +last, " error
messages") introduces a write to a register that does not exist in
Coldfire.
Move the FEC_FTRL register access inside the FEC_QUIRK_HAS_RACC 'if' block,
so that we guarantee it will not be used on Coldfire CPUs.
Reported-by: Greg Ungerer <gerg@uclinux.org>
Signed-off-by: Fabio Estevam <fabio.estevam@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
The mvneta is also used in some Marvell berlin family SoCs which may
have 64bytes cacheline size. Replace the MVNETA_CPU_D_CACHE_LINE_SIZE
usage with L1_CACHE_BYTES.
And since dma_alloc_coherent() is always cacheline size aligned, so
remove the align checks.
Signed-off-by: Jisheng Zhang <jszhang@marvell.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
The mvpp2 ip maybe used in SoCs which may have have 64bytes cacheline
size. Replace the MVPP2_CPU_D_CACHE_LINE_SIZE with L1_CACHE_BYTES.
And since dma_alloc_coherent() is always cacheline size aligned, so
remove the align checks.
Signed-off-by: Jisheng Zhang <jszhang@marvell.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Some of the vendor-specific bootloaders set up this part
of the initialization for us, so this was never added.
However, since upstream bootloaders don't initialize the
chip specifically, they leave the fiber MII's PDOWN flag
set, which means that the CPU port doesn't connect.
This patch checks whether this flag has been clear prior
by something else, and if not make us clear it.
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Patrick Uiterwijk <patrick@puiterwijk.org>
Tested-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Add versions of the phy_page_read and _write functions to
be used in a context where the SMI mutex is held.
Tested-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com>
Reviewed-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com>
Signed-off-by: Patrick Uiterwijk <patrick@puiterwijk.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Use dma_request_chan instead of dma_request_slave_channel,
in this case we can check EPROBE_DEFER without static
warning.
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Shawn Lin <shawn.lin@rock-chips.com>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
IS_ERR_VALUE should be used only with unsigned long type,
signed types should use comparison 'ret < 0'
This patch removes such usages.
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
This patch fixes following static checker warning, by initializing the
ret to -EINVAL, as one of the code path in lpass_platform_pcm_new()
uses this variable uninitialized.
sound/soc/qcom/lpass-platform.c:555 lpass_platform_pcm_new()
error: uninitialized symbol 'ret'.
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
The right variable definition should be wb_congested_state that
include WB_async_congested and WB_sync_congested. So fix it.
Signed-off-by: Kaixu Xia <xiakaixu@huawei.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@fb.com>
Extending the lifetime of the media_device struct is not handled well
by the core, as it will erase some data from the struct, when
media_device_cleanup() is called after unregistering it.
While we have a fixup patch for it already, the usage of those new
functions are needed only when we share data with other drivers.
So, better to revert the changes.
This reverts commit 182dde7c5d ("[media] media: au0828 change
to use Managed Media Controller API")
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
Unfortunately, this patch caused several regressions at au0828 and
snd-usb-audio, like this one:
https://bugzilla.kernel.org/show_bug.cgi?id=115561
It also showed several troubles at the MC core that handles pretty
poorly the memory protections and data lifetime management.
So, better to revert it and fix the core before reapplying this
change.
This reverts commit aebb2b89bf ("[media] sound/usb: Use Media
Controller API to share media resources")'
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
The au0828 dev_state is actually a bit mask. It should not be
checking with "==" but, instead, with a logic and. There are some
places where it was doing it wrong.
Fix that by replacing the dev_state set/clear/test with the
bitops.
As reviewed by Shuah:
"Looks good. Tested running bind/unbind au0828 loop for 1000 times.
Didn't see any problems and the v4l2_querycap() problem has been
fixed with this patch.
After the above test, ran bind/unbind snd_usb_audio 1000 times.
Didn't see any problems. Generated media graph and the graph
looks good."
Cc: stable@vger.kernel.org
Reviewed-by: Shuah Khan <shuahkh@osg.samsung.com>
Tested-by: Shuah Khan <shuahkh@osg.samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
au0828_v4l2_close() check for dev_state == DEV_DISCONNECTED will fail to
detect the device disconnected state correctly, if au0828_v4l2_open() runs
to set the DEV_INITIALIZED bit. A loop test of bind/unbind found this bug
by increasing the likelihood of au0828_v4l2_open() occurring while unbind
is in progress. When au0828_v4l2_close() fails to detect that the device
is in disconnect state, it attempts to power down the device and fails with
the following general protection fault:
[ 260.992962] Call Trace:
[ 260.993008] [<ffffffffa0f80f0f>] ? xc5000_sleep+0x8f/0xd0 [xc5000]
[ 260.993095] [<ffffffffa0f6803c>] ? fe_standby+0x3c/0x50 [tuner]
[ 260.993186] [<ffffffffa0ef541c>] au0828_v4l2_close+0x53c/0x620 [au0828]
[ 260.993298] [<ffffffffa0d08ec0>] v4l2_release+0xf0/0x210 [videodev]
[ 260.993382] [<ffffffff81570f9c>] __fput+0x1fc/0x6c0
[ 260.993449] [<ffffffff815714ce>] ____fput+0xe/0x10
[ 260.993519] [<ffffffff8116eb83>] task_work_run+0x133/0x1f0
[ 260.993602] [<ffffffff810035d0>] exit_to_usermode_loop+0x140/0x170
[ 260.993681] [<ffffffff810061ca>] syscall_return_slowpath+0x16a/0x1a0
[ 260.993754] [<ffffffff82835fb3>] entry_SYSCALL_64_fastpath+0xa6/0xa8
Cc: stable@vger.kernel.org
Signed-off-by: Shuah Khan <shuahkh@osg.samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
