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Pull workqueue updates from Tejun Heo: "Mostly patches to initialize workqueue subsystem earlier and get rid of keventd_up(). The patches were headed for the last merge cycle but got delayed due to a bug found late minute, which is fixed now. Also, to help debugging, destroy_workqueue() is more chatty now on a sanity check failure." * 'for-4.10' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq: workqueue: move wq_numa_init() to workqueue_init() workqueue: remove keventd_up() debugobj, workqueue: remove keventd_up() usage slab, workqueue: remove keventd_up() usage power, workqueue: remove keventd_up() usage tty, workqueue: remove keventd_up() usage mce, workqueue: remove keventd_up() usage workqueue: make workqueue available early during boot workqueue: dump workqueue state on sanity check failures in destroy_workqueue() 
Linus Torvalds
commited |
c11a6cfb01 | |
Only formating changes. Signed-off-by: Silvio Fricke <silvio.fricke@gmail.com> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jonathan Corbet <corbet@lwn.net> 
Silvio Fricke
authored and
 Jonathan Corbet
commited |
42412c3aae | |
Tejun Heo
commited |
8bc4a04455 | |
keventd_up() no longer has in-kernel users. Remove it and make wq_online static. Signed-off-by: Tejun Heo <tj@kernel.org>
Tejun Heo
commited |
863b710b66 | |
Workqueue is currently initialized in an early init call; however,
there are cases where early boot code has to be split and reordered to
come after workqueue initialization or the same code path which makes
use of workqueues is used both before workqueue initailization and
after. The latter cases have to gate workqueue usages with
keventd_up() tests, which is nasty and easy to get wrong.
Workqueue usages have become widespread and it'd be a lot more
convenient if it can be used very early from boot. This patch splits
workqueue initialization into two steps. workqueue_init_early() which
sets up the basic data structures so that workqueues can be created
and work items queued, and workqueue_init() which actually brings up
workqueues online and starts executing queued work items. The former
step can be done very early during boot once memory allocation,
cpumasks and idr are initialized. The latter right after kthreads
become available.
This allows work item queueing and canceling from very early boot
which is what most of these use cases want.
* As systemd_wq being initialized doesn't indicate that workqueue is
fully online anymore, update keventd_up() to test wq_online instead.
The follow-up patches will get rid of all its usages and the
function itself.
* Flushing doesn't make sense before workqueue is fully initialized.
The flush functions trigger WARN and return immediately before fully
online.
* Work items are never in-flight before fully online. Canceling can
always succeed by skipping the flush step.
* Some code paths can no longer assume to be called with irq enabled
as irq is disabled during early boot. Use irqsave/restore
operations instead.
v2: Watchdog init, which requires timer to be running, moved from
workqueue_init_early() to workqueue_init().
Signed-off-by: Tejun Heo <tj@kernel.org>
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/CA+55aFx0vPuMuxn00rBSM192n-Du5uxy+4AvKa0SBSOVJeuCGg@mail.gmail.com
Tejun Heo
commited |
3347fa0928 | |
Like cancel_delayed_work(), but for regular work. Signed-off-by: Jens Axboe <axboe@fb.com> Mehed-by: Tejun Heo <tj@kernel.org> Acked-by: Tejun Heo <tj@kernel.org> 
Jens Axboe
commited |
f72b8792d1 | |
Get rid of the prio ordering of the separate notifiers and use a proper state callback pair. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de> Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Acked-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Lai Jiangshan <jiangshanlai@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Nicolas Iooss <nicolas.iooss_linux@m4x.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: rt@linutronix.de Link: http://lkml.kernel.org/r/20160713153335.197083890@linutronix.de Signed-off-by: Ingo Molnar <mingo@kernel.org> 
Thomas Gleixner
authored and
 Ingo Molnar
commited |
7ee681b252 | |
Tejun Heo
commited |
23d11a58a9 | |
Workqueue stalls can happen from a variety of usage bugs such as
missing WQ_MEM_RECLAIM flag or concurrency managed work item
indefinitely staying RUNNING. These stalls can be extremely difficult
to hunt down because the usual warning mechanisms can't detect
workqueue stalls and the internal state is pretty opaque.
To alleviate the situation, this patch implements workqueue lockup
detector. It periodically monitors all worker_pools periodically and,
if any pool failed to make forward progress longer than the threshold
duration, triggers warning and dumps workqueue state as follows.
BUG: workqueue lockup - pool cpus=0 node=0 flags=0x0 nice=0 stuck for 31s!
Showing busy workqueues and worker pools:
workqueue events: flags=0x0
pwq 0: cpus=0 node=0 flags=0x0 nice=0 active=17/256
pending: monkey_wrench_fn, e1000_watchdog, cache_reap, vmstat_shepherd, release_one_tty, release_one_tty, release_one_tty, release_one_tty, release_one_tty, release_one_tty, release_one_tty, release_one_tty, release_one_tty, release_one_tty, release_one_tty, release_one_tty, cgroup_release_agent
workqueue events_power_efficient: flags=0x80
pwq 0: cpus=0 node=0 flags=0x0 nice=0 active=2/256
pending: check_lifetime, neigh_periodic_work
workqueue cgroup_pidlist_destroy: flags=0x0
pwq 0: cpus=0 node=0 flags=0x0 nice=0 active=1/1
pending: cgroup_pidlist_destroy_work_fn
...
The detection mechanism is controller through kernel parameter
workqueue.watchdog_thresh and can be updated at runtime through the
sysfs module parameter file.
v2: Decoupled from softlockup control knobs.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Don Zickus <dzickus@redhat.com>
Cc: Ulrich Obergfell <uobergfe@redhat.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Chris Mason <clm@fb.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Tejun Heo
commited |
82607adcf9 | |
There are some errors in the docbook comments in workqueue.h that cause warnings when the docs are built; this only recently came to light because these comments were not used until now. Fix the comments to make the warnings go away. The "args..." "fix" is a hack. kerneldoc doesn't deal properly with named variadic arguments in macros, so all I've really achieved here is to make it shut up. Fixing kerneldoc will have to wait for more time. Signed-off-by: Jonathan Corbet <corbet@lwn.net> Signed-off-by: Tejun Heo <tj@kernel.org>
Jonathan Corbet
authored and
Tejun Heo
commited |
355c06633e | |
flush_scheduled_work() is just a simple call to flush_work(). Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com> Signed-off-by: Tejun Heo <tj@kernel.org> 
Lai Jiangshan
authored and
Tejun Heo
commited |
37b1ef31a5 | |
Allow to modify the low-level unbound workqueues cpumask through sysfs. This is performed by traversing the entire workqueue list and calling apply_wqattrs_prepare() on the unbound workqueues with the new low level mask. Only after all the preparation are done, we commit them all together. Ordered workqueues are ignored from the low level unbound workqueue cpumask, it will be handled in near future. All the (default & per-node) pwqs are mandatorily controlled by the low level cpumask. If the user configured cpumask doesn't overlap with the low level cpumask, the low level cpumask will be used for the wq instead. The comment of wq_calc_node_cpumask() is updated and explicitly requires that its first argument should be the attrs of the default pwq. The default wq_unbound_cpumask is cpu_possible_mask. The workqueue subsystem doesn't know its best default value, let the system manager or the other subsystem set it when needed. Changed from V8: merge the calculating code for the attrs of the default pwq together. minor change the code&comments for saving the user configured attrs. remove unnecessary list_del(). minor update the comment of wq_calc_node_cpumask(). update the comment of workqueue_set_unbound_cpumask(); Cc: Christoph Lameter <cl@linux.com> Cc: Kevin Hilman <khilman@linaro.org> Cc: Lai Jiangshan <laijs@cn.fujitsu.com> Cc: Mike Galbraith <bitbucket@online.de> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Tejun Heo <tj@kernel.org> Cc: Viresh Kumar <viresh.kumar@linaro.org> Cc: Frederic Weisbecker <fweisbec@gmail.com> Original-patch-by: Frederic Weisbecker <fweisbec@gmail.com> Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com> Signed-off-by: Tejun Heo <tj@kernel.org>
Lai Jiangshan
authored and
Tejun Heo
commited |
042f7df15a | |
Workqueues are used extensively throughout the kernel but sometimes
it's difficult to debug stalls involving work items because visibility
into its inner workings is fairly limited. Although sysrq-t task dump
annotates each active worker task with the information on the work
item being executed, it is challenging to find out which work items
are pending or delayed on which queues and how pools are being
managed.
This patch implements show_workqueue_state() which dumps all busy
workqueues and pools and is called from the sysrq-t handler. At the
end of sysrq-t dump, something like the following is printed.
Showing busy workqueues and worker pools:
...
workqueue filler_wq: flags=0x0
pwq 2: cpus=1 node=0 flags=0x0 nice=0 active=2/256
in-flight: 491:filler_workfn, 507:filler_workfn
pwq 0: cpus=0 node=0 flags=0x0 nice=0 active=2/256
in-flight: 501:filler_workfn
pending: filler_workfn
...
workqueue test_wq: flags=0x8
pwq 2: cpus=1 node=0 flags=0x0 nice=0 active=1/1
in-flight: 510(RESCUER):test_workfn BAR(69) BAR(500)
delayed: test_workfn1 BAR(492), test_workfn2
...
pool 0: cpus=0 node=0 flags=0x0 nice=0 workers=2 manager: 137
pool 2: cpus=1 node=0 flags=0x0 nice=0 workers=3 manager: 469
pool 3: cpus=1 node=0 flags=0x0 nice=-20 workers=2 idle: 16
pool 8: cpus=0-3 flags=0x4 nice=0 workers=2 manager: 62
The above shows that test_wq is executing test_workfn() on pid 510
which is the rescuer and also that there are two tasks 69 and 500
waiting for the work item to finish in flush_work(). As test_wq has
max_active of 1, there are two work items for test_workfn1() and
test_workfn2() which are delayed till the current work item is
finished. In addition, pid 492 is flushing test_workfn1().
The work item for test_workfn() is being executed on pwq of pool 2
which is the normal priority per-cpu pool for CPU 1. The pool has
three workers, two of which are executing filler_workfn() for
filler_wq and the last one is assuming the manager role trying to
create more workers.
This extra workqueue state dump will hopefully help chasing down hangs
involving workqueues.
v3: cpulist_pr_cont() replaced with "%*pbl" printf formatting.
v2: As suggested by Andrew, minor formatting change in pr_cont_work(),
printk()'s replaced with pr_info()'s, and cpumask printing now
uses cpulist_pr_cont().
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
CC: Ingo Molnar <mingo@redhat.com>
Tejun Heo
commited |
3494fc3084 | |
cancel[_delayed]_work_sync() are implemented using
__cancel_work_timer() which grabs the PENDING bit using
try_to_grab_pending() and then flushes the work item with PENDING set
to prevent the on-going execution of the work item from requeueing
itself.
try_to_grab_pending() can always grab PENDING bit without blocking
except when someone else is doing the above flushing during
cancelation. In that case, try_to_grab_pending() returns -ENOENT. In
this case, __cancel_work_timer() currently invokes flush_work(). The
assumption is that the completion of the work item is what the other
canceling task would be waiting for too and thus waiting for the same
condition and retrying should allow forward progress without excessive
busy looping
Unfortunately, this doesn't work if preemption is disabled or the
latter task has real time priority. Let's say task A just got woken
up from flush_work() by the completion of the target work item. If,
before task A starts executing, task B gets scheduled and invokes
__cancel_work_timer() on the same work item, its try_to_grab_pending()
will return -ENOENT as the work item is still being canceled by task A
and flush_work() will also immediately return false as the work item
is no longer executing. This puts task B in a busy loop possibly
preventing task A from executing and clearing the canceling state on
the work item leading to a hang.
task A task B worker
executing work
__cancel_work_timer()
try_to_grab_pending()
set work CANCELING
flush_work()
block for work completion
completion, wakes up A
__cancel_work_timer()
while (forever) {
try_to_grab_pending()
-ENOENT as work is being canceled
flush_work()
false as work is no longer executing
}
This patch removes the possible hang by updating __cancel_work_timer()
to explicitly wait for clearing of CANCELING rather than invoking
flush_work() after try_to_grab_pending() fails with -ENOENT.
Link: http://lkml.kernel.org/g/20150206171156.GA8942@axis.com
v3: bit_waitqueue() can't be used for work items defined in vmalloc
area. Switched to custom wake function which matches the target
work item and exclusive wait and wakeup.
v2: v1 used wake_up() on bit_waitqueue() which leads to NULL deref if
the target bit waitqueue has wait_bit_queue's on it. Use
DEFINE_WAIT_BIT() and __wake_up_bit() instead. Reported by Tomeu
Vizoso.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Rabin Vincent <rabin.vincent@axis.com>
Cc: Tomeu Vizoso <tomeu.vizoso@gmail.com>
Cc: stable@vger.kernel.org
Tested-by: Jesper Nilsson <jesper.nilsson@axis.com>
Tested-by: Rabin Vincent <rabin.vincent@axis.com>
Tejun Heo
commited |
8603e1b300 | |
checkpatch.pl complained about two single statement macros in do while (0) loops. The loops and the trailing semicolons are now removed, which makes checkpatch happy and the two macros consistent with the rest of the file. Signed-off-by: Valentin Rothberg <valentinrothberg@gmail.com> Signed-off-by: Tejun Heo <tj@kernel.org> 
Valentin Rothberg
authored and
Tejun Heo
commited |
9da7dae94f | |
create_singlethread_workqueue() is a compat interface for single threaded workqueue which maps to ordered workqueue w/ rescuer in the current implementation. create_singlethread_workqueue() currently implemented by invoking alloc_workqueue() w/ appropriate parameters.
Tejun Heo
commited |
e09c2c2954 | |
In
Lai Jiangshan
authored and
Tejun Heo
commited |
cafebac153 | |
WORK_CPU_END is totally unused since
Lai Jiangshan
authored and
Tejun Heo
commited |
79bc251f0e | |
system_highpri_wq is exported to modules via EXPORT_SYMBOL_GPL(), but it was forgotten to be declared in workqueue.h. So we add the declaration and a short description for it. tj: Minor comment tweak. Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com> Signed-off-by: Tejun Heo <tj@kernel.org>
Lai Jiangshan
authored and
Tejun Heo
commited |
73e4354444 | |
system_nrt[_freezable]_wq were deprecated by
Jingoo Han
authored and
Tejun Heo
commited |
cf416171e7 | |
flush[_delayed]_work_sync() were deprecated by
Jingoo Han
authored and
Tejun Heo
commited |
1a56f2aa47 | |
Pull timer changes from Thomas Gleixner:
"This assorted collection provides:
- A new timer based timer broadcast feature for systems which do not
provide a global accessible timer device. That allows those
systems to put CPUs into deep idle states where the per cpu timer
device stops.
- A few NOHZ_FULL related improvements to the timer wheel
- The usual updates to timer devices found in ARM SoCs
- Small improvements and updates all over the place"
* 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (44 commits)
tick: Remove code duplication in tick_handle_periodic()
tick: Fix spelling mistake in tick_handle_periodic()
x86: hpet: Use proper destructor for delayed work
workqueue: Provide destroy_delayed_work_on_stack()
clocksource: CMT, MTU2, TMU and STI should depend on GENERIC_CLOCKEVENTS
timer: Remove code redundancy while calling get_nohz_timer_target()
hrtimer: Rearrange comments in the order struct members are declared
timer: Use variable head instead of &work_list in __run_timers()
clocksource: exynos_mct: silence a static checker warning
arm: zynq: Add support for cpufreq
arm: zynq: Don't use arm_global_timer with cpufreq
clocksource/cadence_ttc: Overhaul clocksource frequency adjustment
clocksource/cadence_ttc: Call clockevents_update_freq() with IRQs enabled
clocksource: Add Kconfig entries for CMT, MTU2, TMU and STI
sh: Remove Kconfig entries for TMU, CMT and MTU2
ARM: shmobile: Remove CMT, TMU and STI Kconfig entries
clocksource: armada-370-xp: Use atomic access for shared registers
clocksource: orion: Use atomic access for shared registers
clocksource: timer-keystone: Delete unnecessary variable
clocksource: timer-keystone: introduce clocksource driver for Keystone
...
Linus Torvalds
commited |
1ead658124 | |
Tejun Heo has made WQ_NON_REENTRANT useless in the
ZhangZhen
authored and
Tejun Heo
commited |
59ff3eb6d6 | |
If a delayed or deferrable work is on stack we need to tell debug objects that we are destroying the timer and the work. Otherwise we leak the tracking object. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Vince Weaver <vincent.weaver@maine.edu> Acked-by: Tejun Heo <tj@kernel.org> Link: http://lkml.kernel.org/r/20140323141939.911487677@linutronix.de Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Thomas Gleixner
commited |
ea2e64f280 | |
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> Signed-off-by: Tejun Heo <tj@kernel.org> 
Geert Uytterhoeven
authored and
Tejun Heo
commited |
41f50094b2 | |
Peter Hurley noticed that since
Tejun Heo
commited |
f073f9229f | |
To receive
Tejun Heo
commited |
7104ce9b34 | |
__cancel_delayed_work() was deprecated by
Tan Xiaojun
authored and
Tejun Heo
commited |
90d88bd754 | |
Tommi noticed a 'funny' lock class name: "%s#5" from a lock acquired in
process_one_work().
Maybe #fmt plus #args could be used as the lock_name to give some more
information for some fmt string like the above.
__builtin_constant_p() check is removed (as there seems no good way to
check all the variables in args list). However, by removing the check,
it only adds two additional "s for those constants.
Some lockdep name examples printed out after the change:
lockdep name wq->name
"events_long" events_long
"%s"("khelper") khelper
"xfs-data/%s"mp->m_fsname xfs-data/dm-3
Signed-off-by: Li Zhong <zhong@linux.vnet.ibm.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Li Zhong
authored and
Tejun Heo
commited |
fada94ee64 | |
|
1207637304 | |
For the workqueue creation interfaces that do not expect format strings, make sure they cannot accidently be parsed that way. Additionally, clean up calls made with a single parameter that would be handled as a format string. Many callers are passing potentially dynamic string content, so use "%s" in those cases to avoid any potential accidents. Signed-off-by: Kees Cook <keescook@chromium.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> 
Kees Cook
authored and
Linus Torvalds
commited |
d8537548c9 | |
This patch adds system wide workqueues aligned towards power saving. This is done by allocating them with WQ_UNBOUND flag if 'wq_power_efficient' is set to 'true'. tj: updated comments a bit. Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Tejun Heo <tj@kernel.org> 
Viresh Kumar
authored and
Tejun Heo
commited |
0668106ca3 | |
Workqueues can be performance or power-oriented. Currently, most workqueues are
bound to the CPU they were created on. This gives good performance (due to cache
effects) at the cost of potentially waking up otherwise idle cores (Idle from
scheduler's perspective. Which may or may not be physically idle) just to
process some work. To save power, we can allow the work to be rescheduled on a
core that is already awake.
Workqueues created with the WQ_UNBOUND flag will allow some power savings.
However, we don't change the default behaviour of the system. To enable
power-saving behaviour, a new config option CONFIG_WQ_POWER_EFFICIENT needs to
be turned on. This option can also be overridden by the
workqueue.power_efficient boot parameter.
tj: Updated config description and comments. Renamed
CONFIG_WQ_POWER_EFFICIENT to CONFIG_WQ_POWER_EFFICIENT_DEFAULT.
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Reviewed-by: Amit Kucheria <amit.kucheria@linaro.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
Viresh Kumar
authored and
Tejun Heo
commited |
cee22a1505 | |
One of the problems that arise when converting dedicated custom threadpool to workqueue is that the shared worker pool used by workqueue anonimizes each worker making it more difficult to identify what the worker was doing on which target from the output of sysrq-t or debug dump from oops, BUG() and friends. This patch implements set_worker_desc() which can be called from any workqueue work function to set its description. When the worker task is dumped for whatever reason - sysrq-t, WARN, BUG, oops, lockdep assertion and so on - the description will be printed out together with the workqueue name and the worker function pointer. The printing side is implemented by print_worker_info() which is called from functions in task dump paths - sched_show_task() and dump_stack_print_info(). print_worker_info() can be safely called on any task in any state as long as the task struct itself is accessible. It uses probe_*() functions to access worker fields. It may print garbage if something went very wrong, but it wouldn't cause (another) oops. The description is currently limited to 24bytes including the terminating \0. worker->desc_valid and workder->desc[] are added and the 64 bytes marker which was already incorrect before adding the new fields is moved to the correct position. Here's an example dump with writeback updated to set the bdi name as worker desc. Hardware name: Bochs Modules linked in: Pid: 7, comm: kworker/u9:0 Not tainted 3.9.0-rc1-work+ #1 Workqueue: writeback bdi_writeback_workfn (flush-8:0) ffffffff820a3ab0 ffff88000f6e9cb8 ffffffff81c61845 ffff88000f6e9cf8 ffffffff8108f50f 0000000000000000 0000000000000000 ffff88000cde16b0 ffff88000cde1aa8 ffff88001ee19240 ffff88000f6e9fd8 ffff88000f6e9d08 Call Trace: [<ffffffff81c61845>] dump_stack+0x19/0x1b [<ffffffff8108f50f>] warn_slowpath_common+0x7f/0xc0 [<ffffffff8108f56a>] warn_slowpath_null+0x1a/0x20 [<ffffffff81200150>] bdi_writeback_workfn+0x2a0/0x3b0 ... Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ingo Molnar <mingo@redhat.com> Acked-by: Jan Kara <jack@suse.cz> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Dave Chinner <david@fromorbit.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Tejun Heo
authored and
Linus Torvalds
commited |
3d1cb2059d | |
Unbound workqueues are now NUMA aware. Let's add some control knobs and update sysfs interface accordingly. * Add kernel param workqueue.numa_disable which disables NUMA affinity globally. * Replace sysfs file "pool_id" with "pool_ids" which contain node:pool_id pairs. This change is userland-visible but "pool_id" hasn't seen a release yet, so this is okay. * Add a new sysf files "numa" which can toggle NUMA affinity on individual workqueues. This is implemented as attrs->no_numa whichn is special in that it isn't part of a pool's attributes. It only affects how apply_workqueue_attrs() picks which pools to use. After "pool_ids" change, first_pwq() doesn't have any user left. Removed. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Tejun Heo
commited |
d55262c4d1 | |
There's no reason to make these trivial wrappers full (exported) functions. Inline the followings. queue_work() queue_delayed_work() mod_delayed_work() schedule_work_on() schedule_work() schedule_delayed_work_on() schedule_delayed_work() keventd_up() Signed-off-by: Tejun Heo <tj@kernel.org>
Tejun Heo
commited |
8425e3d5bd | |
Implement a function which queries whether it currently is running off a workqueue rescuer. This will be used to convert writeback to workqueue. Signed-off-by: Tejun Heo <tj@kernel.org>
Tejun Heo
commited |
e626761691 | |
There are cases where workqueue users want to expose control knobs to
userland. e.g. Unbound workqueues with custom attributes are
scheduled to be used for writeback workers and depending on
configuration it can be useful to allow admins to tinker with the
priority or allowed CPUs.
This patch implements workqueue_sysfs_register(), which makes the
workqueue visible under /sys/bus/workqueue/devices/WQ_NAME. There
currently are two attributes common to both per-cpu and unbound pools
and extra attributes for unbound pools including nice level and
cpumask.
If alloc_workqueue*() is called with WQ_SYSFS,
workqueue_sysfs_register() is called automatically as part of
workqueue creation. This is the preferred method unless the workqueue
user wants to apply workqueue_attrs before making the workqueue
visible to userland.
v2: Disallow exposing ordered workqueues as ordered workqueues can't
be tuned in any way.
Signed-off-by: Tejun Heo <tj@kernel.org>
Tejun Heo
commited |
226223ab3c | |
Adjusting max_active of or applying new workqueue_attrs to an ordered workqueue breaks its ordering guarantee. The former is obvious. The latter is because applying attrs creates a new pwq (pool_workqueue) and there is no ordering constraint between the old and new pwqs. Make apply_workqueue_attrs() and workqueue_set_max_active() trigger WARN_ON() if those operations are requested on an ordered workqueue and fail / ignore respectively. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Tejun Heo
commited |
8719dceae2 | |
We're gonna add another internal WQ flag. Let's make the distinction clear. Prefix WQ_DRAINING with __ and move it to bit 16. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Tejun Heo
commited |
618b01eb42 | |
Implement apply_workqueue_attrs() which applies workqueue_attrs to the specified unbound workqueue by creating a new pwq (pool_workqueue) linked to worker_pool with the specified attributes. A new pwq is linked at the head of wq->pwqs instead of tail and __queue_work() verifies that the first unbound pwq has positive refcnt before choosing it for the actual queueing. This is to cover the case where creation of a new pwq races with queueing. As base ref on a pwq won't be dropped without making another pwq the first one, __queue_work() is guaranteed to make progress and not add work item to a dead pwq. init_and_link_pwq() is updated to return the last first pwq the new pwq replaced, which is put by apply_workqueue_attrs(). Note that apply_workqueue_attrs() is almost identical to unbound pwq part of alloc_and_link_pwqs(). The only difference is that there is no previous first pwq. apply_workqueue_attrs() is implemented to handle such cases and replaces unbound pwq handling in alloc_and_link_pwqs(). Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Tejun Heo
commited |
9e8cd2f589 | |
WQ_RESCUER is superflous. WQ_MEM_RECLAIM indicates that the user wants a rescuer and testing wq->rescuer for NULL can answer whether a given workqueue has a rescuer or not. Drop WQ_RESCUER and test wq->rescuer directly. This will help simplifying __alloc_workqueue_key() failure path by allowing it to use destroy_workqueue() on a partially constructed workqueue, which in turn will help implementing dynamic management of pool_workqueues. While at it, clear wq->rescuer after freeing it in destroy_workqueue(). This is a precaution as scheduled changes will make destruction more complex. This patch doesn't introduce any functional changes. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Tejun Heo
commited |
493008a8e4 | |
Introduce struct workqueue_attrs which carries worker attributes -
currently the nice level and allowed cpumask along with helper
routines alloc_workqueue_attrs() and free_workqueue_attrs().
Each worker_pool now carries ->attrs describing the attributes of its
workers. All functions dealing with cpumask and nice level of workers
are updated to follow worker_pool->attrs instead of determining them
from other characteristics of the worker_pool, and init_workqueues()
is updated to set worker_pool->attrs appropriately for all standard
pools.
Note that create_worker() is updated to always perform set_user_nice()
and use set_cpus_allowed_ptr() combined with manual assertion of
PF_THREAD_BOUND instead of kthread_bind(). This simplifies handling
random attributes without affecting the outcome.
This patch doesn't introduce any behavior changes.
v2: Missing cpumask_var_t definition caused build failure on some
archs. linux/cpumask.h included.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: kbuild test robot <fengguang.wu@intel.com>
Reviewed-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Tejun Heo
commited |
7a4e344c56 | |
Workqueue is mixing unsigned int and int for @cpu variables. There's no point in using unsigned int for cpus - many of cpu related APIs take int anyway. Consistently use int for @cpu variables so that we can use negative values to mark special ones. This patch doesn't introduce any visible behavior changes. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Tejun Heo
commited |
d84ff0512f | |
When a work item is off-queue, its work->data contains WORK_STRUCT_* and WORK_OFFQ_* flags. As WORK_OFFQ_* flags are used only while a work item is off-queue, it can occupy bits of work->data which aren't used while off-queue. WORK_OFFQ_* currently only use bits used by on-queue CWQ pointer. As color bits aren't used while off-queue, there's no reason to not use them. Lower WORK_OFFQ_FLAG_BASE from WORK_STRUCT_FLAG_BITS to WORK_STRUCT_COLOR_SHIFT thus giving 4 more bits to off-queue flag space which is also used to record worker_pool ID while off-queue. This doesn't introduce any visible behavior difference. tj: Rewrote the description. Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com> Signed-off-by: Tejun Heo <tj@kernel.org>
Lai Jiangshan
authored and
Tejun Heo
commited |
45d9550a0e | |
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>
Tejun Heo
commited |
112202d909 | |
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>
Lai Jiangshan
authored and
Tejun Heo
commited |
60c057bca2 | |
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>
Lai Jiangshan
authored and
Tejun Heo
commited |
6be195886a | |
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>
Tejun Heo
commited |
7c3eed5cd6 | |
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>
Tejun Heo
commited |
715b06b864 |