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workqueue has moved away from global_cwqs to worker_pools and with the
scheduled custom worker pools, wforkqueues will be associated with
pools which don't have anything to do with CPUs. The workqueue code
went through significant amount of changes recently and mass renaming
isn't likely to hurt much additionally. Let's replace 'cpu' with
'pool' so that it reflects the current design.
* s/struct cpu_workqueue_struct/struct pool_workqueue/
* s/cpu_wq/pool_wq/
* s/cwq/pwq/
This patch is purely cosmetic.
Signed-off-by: Tejun Heo <tj@kernel.org>
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To avoid executing the same work item from multiple CPUs concurrently,
a work_struct records the last pool it was on in its ->data so that,
on the next queueing, the pool can be queried to determine whether the
work item is still executing or not.
A delayed_work goes through timer before actually being queued on the
target workqueue and the timer needs to know the target workqueue and
CPU. This is currently achieved by modifying delayed_work->work.data
such that it points to the cwq which points to the target workqueue
and the last CPU the work item was on. __queue_delayed_work()
extracts the last CPU from delayed_work->work.data and then combines
it with the target workqueue to create new work.data.
The only thing this rather ugly hack achieves is encoding the target
workqueue into delayed_work->work.data without using a separate field,
which could be a trade off one can make; unfortunately, this entangles
work->data management between regular workqueue and delayed_work code
by setting cwq pointer before the work item is actually queued and
becomes a hindrance for further improvements of work->data handling.
This can be easily made sane by adding a target workqueue field to
delayed_work. While delayed_work is used widely in the kernel and
this does make it a bit larger (<5%), I think this is the right
trade-off especially given the prospect of much saner handling of
work->data which currently involves quite tricky memory barrier
dancing, and don't expect to see any measureable effect.
Add delayed_work->wq and drop the delayed_work->work.data overloading.
tj: Rewrote the description.
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
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Now that workqueue has moved away from gcwqs, workqueue no longer has
the need to have a CPU identifier indicating "no cpu associated" - we
now use WORK_OFFQ_POOL_NONE instead - and most uses of WORK_CPU_NONE
are gone.
The only left usage is as the end marker for for_each_*wq*()
iterators, where the name WORK_CPU_NONE is confusing w/o actual
WORK_CPU_NONE usages. Similarly, WORK_CPU_LAST which equals
WORK_CPU_NONE no longer makes sense.
Replace both WORK_CPU_NONE and LAST with WORK_CPU_END. This patch
doesn't introduce any functional difference.
tj: s/WORK_CPU_LAST/WORK_CPU_END/ and rewrote the description.
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
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Currently, when a work item is off-queue, work->data records the CPU
it was last on, which is used to locate the last executing instance
for non-reentrance, flushing, etc.
We're in the process of removing global_cwq and making worker_pool the
top level abstraction. This patch makes work->data point to the pool
it was last associated with instead of CPU.
After the previous WORK_OFFQ_POOL_CPU and worker_poo->id additions,
the conversion is fairly straight-forward. WORK_OFFQ constants and
functions are modified to record and read back pool ID instead.
worker_pool_by_id() is added to allow looking up pool from ID.
get_work_pool() replaces get_work_gcwq(), which is reimplemented using
get_work_pool(). get_work_pool_id() replaces work_cpu().
This patch shouldn't introduce any observable behavior changes.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Lai Jiangshan <laijs@cn.fujitsu.com>
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Currently, when a work item is off queue, high bits of its data
encodes the last CPU it was on. This is scheduled to be changed to
pool ID, which will make it impossible to use WORK_CPU_NONE to
indicate no association.
This patch limits the number of bits which are used for off-queue cpu
number to 31 (so that the max fits in an int) and uses the highest
possible value - WORK_OFFQ_CPU_NONE - to indicate no association.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Lai Jiangshan <laijs@cn.fujitsu.com>
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This function no longer has any external users. Unexport it. It will
be removed later on.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Lai Jiangshan <laijs@cn.fujitsu.com>
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Now that cancel_delayed_work() can be safely called from IRQ handlers,
there's no reason to use __cancel_delayed_work(). Use
cancel_delayed_work() instead of __cancel_delayed_work() and mark the
latter deprecated.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Jens Axboe <axboe@kernel.dk>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Roland Dreier <roland@kernel.org>
Cc: Tomi Valkeinen <tomi.valkeinen@ti.com>
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cancel_delayed_work() can't be called from IRQ handlers due to its use
of del_timer_sync() and can't cancel work items which are already
transferred from timer to worklist.
Also, unlike other flush and cancel functions, a canceled delayed_work
would still point to the last associated cpu_workqueue. If the
workqueue is destroyed afterwards and the work item is re-used on a
different workqueue, the queueing code can oops trying to dereference
already freed cpu_workqueue.
This patch reimplements cancel_delayed_work() using
try_to_grab_pending() and set_work_cpu_and_clear_pending(). This
allows the function to be called from IRQ handlers and makes its
behavior consistent with other flush / cancel functions.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
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Up to now, for delayed_works, try_to_grab_pending() couldn't be used
from IRQ handlers because IRQs may happen while
delayed_work_timer_fn() is in progress leading to indefinite -EAGAIN.
This patch makes delayed_work use the new TIMER_IRQSAFE flag for
delayed_work->timer. This makes try_to_grab_pending() and thus
mod_delayed_work_on() safe to call from IRQ handlers.
Signed-off-by: Tejun Heo <tj@kernel.org>
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Reimplement delayed_work initializers using new timer initializers
which take timer flags. This reduces code duplications and will ease
further initializer changes. This patch also adds a missing
initializer - INIT_DEFERRABLE_WORK_ONSTACK().
Signed-off-by: Tejun Heo <tj@kernel.org>
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Initalizers for deferrable delayed_work are confused.
* __DEFERRED_WORK_INITIALIZER()
* DECLARE_DEFERRED_WORK()
* INIT_DELAYED_WORK_DEFERRABLE()
Rename them to
* __DEFERRABLE_WORK_INITIALIZER()
* DECLARE_DEFERRABLE_WORK()
* INIT_DEFERRABLE_WORK()
This patch doesn't cause any functional changes.
Signed-off-by: Tejun Heo <tj@kernel.org>
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Consistently use the last tab position for '\' line continuation in
complex macro definitions. This is to help the following patches.
This patch is cosmetic.
Signed-off-by: Tejun Heo <tj@kernel.org>
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system_nrt[_freezable]_wq are now spurious. Mark them deprecated and
convert all users to system[_freezable]_wq.
If you're cc'd and wondering what's going on: Now all workqueues are
non-reentrant, so there's no reason to use system_nrt[_freezable]_wq.
Please use system[_freezable]_wq instead.
This patch doesn't make any functional difference.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-By: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: David Airlie <airlied@linux.ie>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: David Howells <dhowells@redhat.com>
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flush[_delayed]_work_sync() are now spurious. Mark them deprecated
and convert all users to flush[_delayed]_work().
If you're cc'd and wondering what's going on: Now all workqueues are
non-reentrant and the regular flushes guarantee that the work item is
not pending or running on any CPU on return, so there's no reason to
use the sync flushes at all and they're going away.
This patch doesn't make any functional difference.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: Ian Campbell <ian.campbell@citrix.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Mattia Dongili <malattia@linux.it>
Cc: Kent Yoder <key@linux.vnet.ibm.com>
Cc: David Airlie <airlied@linux.ie>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Karsten Keil <isdn@linux-pingi.de>
Cc: Bryan Wu <bryan.wu@canonical.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Alasdair Kergon <agk@redhat.com>
Cc: Mauro Carvalho Chehab <mchehab@infradead.org>
Cc: Florian Tobias Schandinat <FlorianSchandinat@gmx.de>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: linux-wireless@vger.kernel.org
Cc: Anton Vorontsov <cbou@mail.ru>
Cc: Sangbeom Kim <sbkim73@samsung.com>
Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Eric Van Hensbergen <ericvh@gmail.com>
Cc: Takashi Iwai <tiwai@suse.de>
Cc: Steven Whitehouse <swhiteho@redhat.com>
Cc: Petr Vandrovec <petr@vandrovec.name>
Cc: Mark Fasheh <mfasheh@suse.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Avi Kivity <avi@redhat.com>
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Now that all workqueues are non-reentrant, system[_freezable]_wq() are
equivalent to system_nrt[_freezable]_wq(). Replace the latter with
wrappers around system[_freezable]_wq(). The wrapping goes through
inline functions so that __deprecated can be added easily.
Signed-off-by: Tejun Heo <tj@kernel.org>
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Now that all workqueues are non-reentrant, flush[_delayed]_work_sync()
are equivalent to flush[_delayed]_work(). Drop the separate
implementation and make them thin wrappers around
flush[_delayed]_work().
* start_flush_work() no longer takes @wait_executing as the only left
user - flush_work() - always sets it to %true.
* __cancel_work_timer() uses flush_work() instead of wait_on_work().
Signed-off-by: Tejun Heo <tj@kernel.org>
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delayed_work encodes the workqueue to use and the last CPU in
delayed_work->work.data while it's on timer. The target CPU is
implicitly recorded as the CPU the timer is queued on and
delayed_work_timer_fn() queues delayed_work->work to the CPU it is
running on.
Unfortunately, this leaves flush_delayed_work[_sync]() no way to find
out which CPU the delayed_work was queued for when they try to
re-queue after killing the timer. Currently, it chooses the local CPU
flush is running on. This can unexpectedly move a delayed_work queued
on a specific CPU to another CPU and lead to subtle errors.
There isn't much point in trying to save several bytes in struct
delayed_work, which is already close to a hundred bytes on 64bit with
all debug options turned off. This patch adds delayed_work->cpu to
remember the CPU it's queued for.
Note that if the timer is migrated during CPU down, the work item
could be queued to the downed global_cwq after this change. As a
detached global_cwq behaves like an unbound one, this doesn't change
much for the delayed_work.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
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Workqueue was lacking a mechanism to modify the timeout of an already
pending delayed_work. delayed_work users have been working around
this using several methods - using an explicit timer + work item,
messing directly with delayed_work->timer, and canceling before
re-queueing, all of which are error-prone and/or ugly.
This patch implements mod_delayed_work[_on]() which behaves similarly
to mod_timer() - if the delayed_work is idle, it's queued with the
given delay; otherwise, its timeout is modified to the new value.
Zero @delay guarantees immediate execution.
v2: Updated to reflect try_to_grab_pending() changes. Now safe to be
called from bh context.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Ingo Molnar <mingo@redhat.com>
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There can be two reasons try_to_grab_pending() can fail with -EAGAIN.
One is when someone else is queueing or deqeueing the work item. With
the previous patches, it is guaranteed that PENDING and queued state
will soon agree making it safe to busy-retry in this case.
The other is if multiple __cancel_work_timer() invocations are racing
one another. __cancel_work_timer() grabs PENDING and then waits for
running instances of the target work item on all CPUs while holding
PENDING and !queued. try_to_grab_pending() invoked from another task
will keep returning -EAGAIN while the current owner is waiting.
Not distinguishing the two cases is okay because __cancel_work_timer()
is the only user of try_to_grab_pending() and it invokes
wait_on_work() whenever grabbing fails. For the first case, busy
looping should be fine but wait_on_work() doesn't cause any critical
problem. For the latter case, the new contender usually waits for the
same condition as the current owner, so no unnecessarily extended
busy-looping happens. Combined, these make __cancel_work_timer()
technically correct even without irq protection while grabbing PENDING
or distinguishing the two different cases.
While the current code is technically correct, not distinguishing the
two cases makes it difficult to use try_to_grab_pending() for other
purposes than canceling because it's impossible to tell whether it's
safe to busy-retry grabbing.
This patch adds a mechanism to mark a work item being canceled.
try_to_grab_pending() now disables irq on success and returns -EAGAIN
to indicate that grabbing failed but PENDING and queued states are
gonna agree soon and it's safe to busy-loop. It returns -ENOENT if
the work item is being canceled and it may stay PENDING && !queued for
arbitrary amount of time.
__cancel_work_timer() is modified to mark the work canceling with
WORK_OFFQ_CANCELING after grabbing PENDING, thus making
try_to_grab_pending() fail with -ENOENT instead of -EAGAIN. Also, it
invokes wait_on_work() iff grabbing failed with -ENOENT. This isn't
necessary for correctness but makes it consistent with other future
users of try_to_grab_pending().
v2: try_to_grab_pending() was testing preempt_count() to ensure that
the caller has disabled preemption. This triggers spuriously if
!CONFIG_PREEMPT_COUNT. Use preemptible() instead. Reported by
Fengguang Wu.
v3: Updated so that try_to_grab_pending() disables irq on success
rather than requiring preemption disabled by the caller. This
makes busy-looping easier and will allow try_to_grap_pending() to
be used from bh/irq contexts.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Fengguang Wu <fengguang.wu@intel.com>
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Low WORK_STRUCT_FLAG_BITS bits of work_struct->data contain
WORK_STRUCT_FLAG_* and flush color. If the work item is queued, the
rest point to the cpu_workqueue with WORK_STRUCT_CWQ set; otherwise,
WORK_STRUCT_CWQ is clear and the bits contain the last CPU number -
either a real CPU number or one of WORK_CPU_*.
Scheduled addition of mod_delayed_work[_on]() requires an additional
flag, which is used only while a work item is off queue. There are
more than enough bits to represent off-queue CPU number on both 32 and
64bits. This patch introduces WORK_OFFQ_FLAG_* which occupy the lower
part of the @work->data high bits while off queue. This patch doesn't
define any actual OFFQ flag yet.
Off-queue CPU number is now shifted by WORK_OFFQ_CPU_SHIFT, which adds
the number of bits used by OFFQ flags to WORK_STRUCT_FLAG_SHIFT, to
make room for OFFQ flags.
To avoid shift width warning with large WORK_OFFQ_FLAG_BITS, ulong
cast is added to WORK_STRUCT_NO_CPU and, just in case, BUILD_BUG_ON()
to check that there are enough bits to accomodate off-queue CPU number
is added.
This patch doesn't make any functional difference.
Signed-off-by: Tejun Heo <tj@kernel.org>
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delayed_work->timer.function is currently initialized during
queue_delayed_work_on(). Export delayed_work_timer_fn() and set
delayed_work timer function during delayed_work initialization
together with other fields.
This ensures the timer function is always valid on an initialized
delayed_work. This is to help mod_delayed_work() implementation.
To detect delayed_work users which diddle with the internal timer,
trigger WARN if timer function doesn't match on queue.
Signed-off-by: Tejun Heo <tj@kernel.org>
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All queueing functions return 1 on success, 0 if the work item was
already pending. Update them to return bool instead. This signifies
better that they don't return 0 / -errno.
This is cleanup and doesn't cause any functional difference.
While at it, fix comment opening for schedule_work_on().
Signed-off-by: Tejun Heo <tj@kernel.org>
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Currently, queue/schedule[_delayed]_work_on() are located below the
counterpart without the _on postifx even though the latter is usually
implemented using the former. Swap them.
This is cleanup and doesn't cause any functional difference.
Signed-off-by: Tejun Heo <tj@kernel.org>
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This patch (as1519) fixes a bug in the block layer's disk-events
polling. The polling is done by a work routine queued on the
system_nrt_wq workqueue. Since that workqueue isn't freezable, the
polling continues even in the middle of a system sleep transition.
Obviously, polling a suspended drive for media changes and such isn't
a good thing to do; in the case of USB mass-storage devices it can
lead to real problems requiring device resets and even re-enumeration.
The patch fixes things by creating a new system-wide, non-reentrant,
freezable workqueue and using it for disk-events polling.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
CC: <stable@kernel.org>
Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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alloc_workqueue() currently expects the passed in @name pointer to remain
accessible. This is inconvenient and a bit silly given that the whole wq
is being dynamically allocated. This patch updates alloc_workqueue() and
friends to take printf format string instead of opaque string and matching
varargs at the end. The name is allocated together with the wq and
formatted.
alloc_ordered_workqueue() is converted to a macro to unify varargs
handling with alloc_workqueue(), and, while at it, add comment to
alloc_workqueue().
None of the current in-kernel users pass in string with '%' as constant
name and this change shouldn't cause any problem.
[akpm@linux-foundation.org: use __printf]
Signed-off-by: Tejun Heo <tj@kernel.org>
Suggested-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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This allows us to move duplicated code in <asm/atomic.h>
(atomic_inc_not_zero() for now) to <linux/atomic.h>
Signed-off-by: Arun Sharma <asharma@fb.com>
Reviewed-by: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: David Miller <davem@davemloft.net>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Acked-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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There are users which want to drain workqueues without destroying it.
Separate out drain functionality from destroy_workqueue() into
drain_workqueue() and make it accessible to workqueue users.
To guarantee forward-progress, only chain queueing is allowed while
drain is in progress. If a new work item which isn't chained from the
running or pending work items is queued while draining is in progress,
WARN_ON_ONCE() is triggered.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: James Bottomley <James.Bottomley@hansenpartnership.com>
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cancel_rearming_delayed_work() and cancel_rearming_delayed_workqueue()
can be removed now.
Signed-off-by: WANG Cong <amwang@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
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wq:fixes-2.6.38 does s/WQ_FREEZEABLE/WQ_FREEZABLE and wq:for-2.6.39
adds new usage of the flag. The combination of the two creates a
build failure after merge. Fix it by renaming all freezeables to
freezables.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
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There are two spellings in use for 'freeze' + 'able' - 'freezable' and
'freezeable'. The former is the more prominent one. The latter is
mostly used by workqueue and in a few other odd places. Unify the
spelling to 'freezable'.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Alan Stern <stern@rowland.harvard.edu>
Acked-by: "Rafael J. Wysocki" <rjw@sisk.pl>
Acked-by: Greg Kroah-Hartman <gregkh@suse.de>
Acked-by: Dmitry Torokhov <dtor@mail.ru>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Alex Dubov <oakad@yahoo.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Steven Whitehouse <swhiteho@redhat.com>
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Add system wide freezeable workqueue.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
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* 'for-2.6.38' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq: (33 commits)
usb: don't use flush_scheduled_work()
speedtch: don't abuse struct delayed_work
media/video: don't use flush_scheduled_work()
media/video: explicitly flush request_module work
ioc4: use static work_struct for ioc4_load_modules()
init: don't call flush_scheduled_work() from do_initcalls()
s390: don't use flush_scheduled_work()
rtc: don't use flush_scheduled_work()
mmc: update workqueue usages
mfd: update workqueue usages
dvb: don't use flush_scheduled_work()
leds-wm8350: don't use flush_scheduled_work()
mISDN: don't use flush_scheduled_work()
macintosh/ams: don't use flush_scheduled_work()
vmwgfx: don't use flush_scheduled_work()
tpm: don't use flush_scheduled_work()
sonypi: don't use flush_scheduled_work()
hvsi: don't use flush_scheduled_work()
xen: don't use flush_scheduled_work()
gdrom: don't use flush_scheduled_work()
...
Fixed up trivial conflict in drivers/media/video/bt8xx/bttv-input.c
as per Tejun.
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'timers-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
MAINTAINERS: Update timer related entries
timers: Use this_cpu_read
timerqueue: Make timerqueue_getnext() static inline
hrtimer: fix timerqueue conversion flub
hrtimers: Convert hrtimers to use timerlist infrastructure
timers: Fixup allmodconfig build issue
timers: Rename timerlist infrastructure to timerqueue
timers: Introduce timerlist infrastructure.
hrtimer: Remove stale comment on curr_timer
timer: Warn when del_timer_sync() is called in hardirq context
timer: Del_timer_sync() can be used in softirq context
timer: Make try_to_del_timer_sync() the same on SMP and UP
posix-timers: Annotate lock_timer()
timer: Permit statically-declared work with deferrable timers
time: Use ARRAY_SIZE macro in timecompare.c
timer: Initialize the field slack of timer_list
timer_list: Remove alignment padding on 64 bit when CONFIG_TIMER_STATS
time: Compensate for rounding on odd-frequency clocksources
Fix up trivial conflict in MAINTAINERS
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There's no in-kernel user left for these two obsolete functions. Mark
them deprecated and schedule for removal during 2.6.39 cycle.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: David S. Miller <davem@davemloft.net>
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Silly though it is, completions and wait_queue_heads use foo_ONSTACK
(COMPLETION_INITIALIZER_ONSTACK, DECLARE_COMPLETION_ONSTACK,
__WAIT_QUEUE_HEAD_INIT_ONSTACK and DECLARE_WAIT_QUEUE_HEAD_ONSTACK) so I
guess workqueues should do the same thing.
s/INIT_WORK_ON_STACK/INIT_WORK_ONSTACK/
s/INIT_DELAYED_WORK_ON_STACK/INIT_DELAYED_WORK_ONSTACK/
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Currently, you have to just define a delayed_work uninitialised, and then
initialise it before first use. That's a tad clumsy. At risk of playing
mind-games with the compiler, fooling it into doing pointer arithmetic
with compile-time-constants, this lets clients properly initialise delayed
work with deferrable timers statically.
This patch was inspired by the issues which lead Artem Bityutskiy to
commit 8eab945c5616fc984 ("sunrpc: make the cache cleaner workqueue
deferrable").
Signed-off-by: Phil Carmody <ext-phil.2.carmody@nokia.com>
Acked-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
Cc: Arjan van de Ven <arjan@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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Commit a25909a4 (lockdep: Add an in_workqueue_context() lockdep-based
test function) added in_workqueue_context() but there hasn't been any
in-kernel user and the lockdep annotation in workqueue is scheduled to
change. Remove the unused function.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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Add WQ_MEM_RECLAIM flag which currently maps to WQ_RESCUER, mark
WQ_RESCUER as internal and replace all external WQ_RESCUER usages to
WQ_MEM_RECLAIM.
This makes the API users express the intent of the workqueue instead
of indicating the internal mechanism used to guarantee forward
progress. This is also to make it cleaner to add more semantics to
WQ_MEM_RECLAIM. For example, if deemed necessary, memory reclaim
workqueues can be made highpri.
This patch doesn't introduce any functional change.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Jeff Garzik <jgarzik@pobox.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Steven Whitehouse <swhiteho@redhat.com>
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Implement flush[_delayed]_work_sync(). These are flush functions
which also make sure no CPU is still executing the target work from
earlier queueing instances. These are similar to
cancel[_delayed]_work_sync() except that the target work item is
flushed instead of cancelled.
Signed-off-by: Tejun Heo <tj@kernel.org>
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Make the following cleanup changes.
* Relocate flush/cancel function prototypes and definitions.
* Relocate wait_on_cpu_work() and wait_on_work() before
try_to_grab_pending(). These will be used to implement
flush_work_sync().
* Make all flush/cancel functions return bool instead of int.
* Update wait_on_cpu_work() and wait_on_work() to return %true if they
actually waited.
* Add / update comments.
This patch doesn't cause any functional changes.
Signed-off-by: Tejun Heo <tj@kernel.org>
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alloc_ordered_workqueue() creates a workqueue which processes each
work itemp one by one in the queued order. This will be used to
replace create_freezeable_workqueue() and
create_singlethread_workqueue().
Signed-off-by: Tejun Heo <tj@kernel.org>
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Update copyright notice and add Documentation/workqueue.txt.
Randy Dunlap, Dave Chinner: misc fixes.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-By: Florian Mickler <florian@mickler.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
Cc: Dave Chinner <david@fromorbit.com>
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cwq->nr_active is used to keep track of how many work items are active
for the cpu workqueue, where 'active' is defined as either pending on
global worklist or executing. This is used to implement the
max_active limit and workqueue freezing. If a work item is queued
after nr_active has already reached max_active, the work item doesn't
increment nr_active and is put on the delayed queue and gets activated
later as previous active work items retire.
try_to_grab_pending() which is used in the cancellation path
unconditionally decremented nr_active whether the work item being
cancelled is currently active or delayed, so cancelling a delayed work
item makes nr_active underflow. This breaks max_active enforcement
and triggers BUG_ON() in destroy_workqueue() later on.
This patch fixes this bug by adding a flag WORK_STRUCT_DELAYED, which
is set while a work item in on the delayed list and making
try_to_grab_pending() decrement nr_active iff the work item is
currently active.
The addition of the flag enlarges cwq alignment to 256 bytes which is
getting a bit too large. It's scheduled to be reduced back to 128
bytes by merging WORK_STRUCT_PENDING and WORK_STRUCT_CWQ in the next
devel cycle.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Johannes Berg <johannes@sipsolutions.net>
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Now that the worklist is global, having works pending after wq
destruction can easily lead to oops and destroy_workqueue() have
several BUG_ON()s to catch these cases. Unfortunately, BUG_ON()
doesn't tell much about how the work became pending after the final
flush_workqueue().
This patch adds WQ_DYING which is set before the final flush begins.
If a work is requested to be queued on a dying workqueue,
WARN_ON_ONCE() is triggered and the request is ignored. This clearly
indicates which caller is trying to queue a work on a dying workqueue
and keeps the system working in most cases.
Locking rule comment is updated such that the 'I' rule includes
modifying the field from destruction path.
Signed-off-by: Tejun Heo <tj@kernel.org>
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* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq: (55 commits)
workqueue: mark init_workqueues() as early_initcall()
workqueue: explain for_each_*cwq_cpu() iterators
fscache: fix build on !CONFIG_SYSCTL
slow-work: kill it
gfs2: use workqueue instead of slow-work
drm: use workqueue instead of slow-work
cifs: use workqueue instead of slow-work
fscache: drop references to slow-work
fscache: convert operation to use workqueue instead of slow-work
fscache: convert object to use workqueue instead of slow-work
workqueue: fix how cpu number is stored in work->data
workqueue: fix mayday_mask handling on UP
workqueue: fix build problem on !CONFIG_SMP
workqueue: fix locking in retry path of maybe_create_worker()
async: use workqueue for worker pool
workqueue: remove WQ_SINGLE_CPU and use WQ_UNBOUND instead
workqueue: implement unbound workqueue
workqueue: prepare for WQ_UNBOUND implementation
libata: take advantage of cmwq and remove concurrency limitations
workqueue: fix worker management invocation without pending works
...
Fixed up conflicts in fs/cifs/* as per Tejun. Other trivial conflicts in
include/linux/workqueue.h, kernel/trace/Kconfig and kernel/workqueue.c
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Mark init_workqueues() as early_initcall() and thus it will be initialized
before smp bringup. init_workqueues() registers for the hotcpu notifier
and thus it should cope with the processors that are brought online after
the workqueues are initialized.
x86 smp bringup code uses workqueues and uses a workaround for the
cold boot process (as the workqueues are initialized post smp_init()).
Marking init_workqueues() as early_initcall() will pave the way for
cleaning up this code.
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
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Once a work starts execution, its data contains the cpu number it was
on instead of pointing to cwq. This is added by commit 7a22ad75
(workqueue: carry cpu number in work data once execution starts) to
reliably determine the work was last on even if the workqueue itself
was destroyed inbetween.
Whether data points to a cwq or contains a cpu number was
distinguished by comparing the value against PAGE_OFFSET. The
assumption was that a cpu number should be below PAGE_OFFSET while a
pointer to cwq should be above it. However, on architectures which
use separate address spaces for user and kernel spaces, this doesn't
hold as PAGE_OFFSET is zero.
Fix it by using an explicit flag, WORK_STRUCT_CWQ, to mark what the
data field contains. If the flag is set, it's pointing to a cwq;
otherwise, it contains a cpu number.
Reported on s390 and microblaze during linux-next testing.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Sachin Sant <sachinp@in.ibm.com>
Reported-by: Michal Simek <michal.simek@petalogix.com>
Reported-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Tested-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Tested-by: Michal Simek <monstr@monstr.eu>
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WQ_SINGLE_CPU combined with @max_active of 1 is used to achieve full
ordering among works queued to a workqueue. The same can be achieved
using WQ_UNBOUND as unbound workqueues always use the gcwq for
WORK_CPU_UNBOUND. As @max_active is always one and benefits from cpu
locality isn't accessible anyway, serving them with unbound workqueues
should be fine.
Drop WQ_SINGLE_CPU support and use WQ_UNBOUND instead. Note that most
single thread workqueue users will be converted to use multithread or
non-reentrant instead and only the ones which require strict ordering
will keep using WQ_UNBOUND + @max_active of 1.
Signed-off-by: Tejun Heo <tj@kernel.org>
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This patch implements unbound workqueue which can be specified with
WQ_UNBOUND flag on creation. An unbound workqueue has the following
properties.
* It uses a dedicated gcwq with a pseudo CPU number WORK_CPU_UNBOUND.
This gcwq is always online and disassociated.
* Workers are not bound to any CPU and not concurrency managed. Works
are dispatched to workers as soon as possible and the only applied
limitation is @max_active. IOW, all unbound workqeueues are
implicitly high priority.
Unbound workqueues can be used as simple execution context provider.
Contexts unbound to any cpu are served as soon as possible.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: David Howells <dhowells@redhat.com>
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