pm24.git/kernel/workqueue.c, branch v3.7-rc3

workqueue: cancel_delayed_work() should return %false if work item is idle

2012-10-24T19:38:16Z

57b30ae77b ("workqueue: reimplement cancel_delayed_work() using try_to_grab_pending()") made cancel_delayed_work() always return %true unless someone else is also trying to cancel the work item, which is broken - if the target work item is idle, the return value should be %false. try_to_grab_pending() indicates that the target work item was idle by zero return value. Use it for return. Note that this brings cancel_delayed_work() in line with __cancel_work_timer() in return value handling. Signed-off-by: Dan Magenheimer Signed-off-by: Tejun Heo LKML-Reference: <444a6439-b1a4-4740-9e7e-bc37267cfe73@default>

Merge branch 'for-3.7' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq

2012-10-02T16:54:49Z

Pull workqueue changes from Tejun Heo: "This is workqueue updates for v3.7-rc1. A lot of activities this round including considerable API and behavior cleanups. * delayed_work combines a timer and a work item. The handling of the timer part has always been a bit clunky leading to confusing cancelation API with weird corner-case behaviors. delayed_work is updated to use new IRQ safe timer and cancelation now works as expected. * Another deficiency of delayed_work was lack of the counterpart of mod_timer() which led to cancel+queue combinations or open-coded timer+work usages. mod_delayed_work[_on]() are added. These two delayed_work changes make delayed_work provide interface and behave like timer which is executed with process context. * A work item could be executed concurrently on multiple CPUs, which is rather unintuitive and made flush_work() behavior confusing and half-broken under certain circumstances. This problem doesn't exist for non-reentrant workqueues. While non-reentrancy check isn't free, the overhead is incurred only when a work item bounces across different CPUs and even in simulated pathological scenario the overhead isn't too high. All workqueues are made non-reentrant. This removes the distinction between flush_[delayed_]work() and flush_[delayed_]_work_sync(). The former is now as strong as the latter and the specified work item is guaranteed to have finished execution of any previous queueing on return. * In addition to the various bug fixes, Lai redid and simplified CPU hotplug handling significantly. * Joonsoo introduced system_highpri_wq and used it during CPU hotplug. There are two merge commits - one to pull in IRQ safe timer from tip/timers/core and the other to pull in CPU hotplug fixes from wq/for-3.6-fixes as Lai's hotplug restructuring depended on them." Fixed a number of trivial conflicts, but the more interesting conflicts were silent ones where the deprecated interfaces had been used by new code in the merge window, and thus didn't cause any real data conflicts. Tejun pointed out a few of them, I fixed a couple more. * 'for-3.7' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq: (46 commits) workqueue: remove spurious WARN_ON_ONCE(in_irq()) from try_to_grab_pending() workqueue: use cwq_set_max_active() helper for workqueue_set_max_active() workqueue: introduce cwq_set_max_active() helper for thaw_workqueues() workqueue: remove @delayed from cwq_dec_nr_in_flight() workqueue: fix possible stall on try_to_grab_pending() of a delayed work item workqueue: use hotcpu_notifier() for workqueue_cpu_down_callback() workqueue: use __cpuinit instead of __devinit for cpu callbacks workqueue: rename manager_mutex to assoc_mutex workqueue: WORKER_REBIND is no longer necessary for idle rebinding workqueue: WORKER_REBIND is no longer necessary for busy rebinding workqueue: reimplement idle worker rebinding workqueue: deprecate __cancel_delayed_work() workqueue: reimplement cancel_delayed_work() using try_to_grab_pending() workqueue: use mod_delayed_work() instead of __cancel + queue workqueue: use irqsafe timer for delayed_work workqueue: clean up delayed_work initializers and add missing one workqueue: make deferrable delayed_work initializer names consistent workqueue: cosmetic whitespace updates for macro definitions workqueue: deprecate system_nrt[_freezable]_wq workqueue: deprecate flush[_delayed]_work_sync() ...

workqueue: remove spurious WARN_ON_ONCE(in_irq()) from try_to_grab_pending()

2012-09-20T17:03:19Z

e0aecdd874 ("workqueue: use irqsafe timer for delayed_work") made try_to_grab_pending() safe to use from irq context but forgot to remove WARN_ON_ONCE(in_irq()). Remove it. Signed-off-by: Tejun Heo Reported-by: Fengguang Wu

workqueue: use cwq_set_max_active() helper for workqueue_set_max_active()

2012-09-19T17:40:48Z

workqueue_set_max_active() may increase ->max_active without activating delayed works and may make the activation order differ from the queueing order. Both aren't strictly bugs but the resulting behavior could be a bit odd. To make things more consistent, use cwq_set_max_active() helper which immediately makes use of the newly increased max_mactive if there are delayed work items and also keeps the activation order. tj: Slight update to description. Signed-off-by: Lai Jiangshan Signed-off-by: Tejun Heo

workqueue: introduce cwq_set_max_active() helper for thaw_workqueues()

2012-09-19T17:40:48Z

Using a helper instead of open code makes thaw_workqueues() clearer. The helper will also be used by the next patch. tj: Slight update to comment and description. Signed-off-by: Lai Jiangshan Signed-off-by: Tejun Heo

workqueue: reimplement work_on_cpu() using system_wq

2012-09-19T17:13:12Z

The existing work_on_cpu() implementation is hugely inefficient. It creates a new kthread, execute that single function and then let the kthread die on each invocation. Now that system_wq can handle concurrent executions, there's no advantage of doing this. Reimplement work_on_cpu() using system_wq which makes it simpler and way more efficient. stable: While this isn't a fix in itself, it's needed to fix a workqueue related bug in cpufreq/powernow-k8. AFAICS, this shouldn't break other existing users. Signed-off-by: Tejun Heo Acked-by: Jiri Kosina Cc: Linus Torvalds Cc: Bjorn Helgaas Cc: Len Brown Cc: Rafael J. Wysocki Cc: stable@vger.kernel.org

workqueue: remove @delayed from cwq_dec_nr_in_flight()

2012-09-18T17:40:00Z

@delayed is now always false for all callers, remove it. tj: Updated description. Signed-off-by: Lai Jiangshan Signed-off-by: Tejun Heo

workqueue: fix possible stall on try_to_grab_pending() of a delayed work item

2012-09-18T17:40:00Z

Currently, when try_to_grab_pending() grabs a delayed work item, it leaves its linked work items alone on the delayed_works. The linked work items are always NO_COLOR and will cause future cwq_activate_first_delayed() increase cwq->nr_active incorrectly, and may cause the whole cwq to stall. For example, state: cwq->max_active = 1, cwq->nr_active = 1 one work in cwq->pool, many in cwq->delayed_works. step1: try_to_grab_pending() removes a work item from delayed_works but leaves its NO_COLOR linked work items on it. step2: Later on, cwq_activate_first_delayed() activates the linked work item increasing ->nr_active. step3: cwq->nr_active = 1, but all activated work items of the cwq are NO_COLOR. When they finish, cwq->nr_active will not be decreased due to NO_COLOR, and no further work items will be activated from cwq->delayed_works. the cwq stalls. Fix it by ensuring the target work item is activated before stealing PENDING in try_to_grab_pending(). This ensures that all the linked work items are activated without incorrectly bumping cwq->nr_active. tj: Updated comment and description. Signed-off-by: Lai Jiangshan Signed-off-by: Tejun Heo Cc: stable@kernel.org

workqueue: use hotcpu_notifier() for workqueue_cpu_down_callback()

2012-09-18T16:59:23Z

workqueue_cpu_down_callback() is used only if HOTPLUG_CPU=y, so hotcpu_notifier() fits better than cpu_notifier(). When HOTPLUG_CPU=y, hotcpu_notifier() and cpu_notifier() are the same. When HOTPLUG_CPU=n, if we use cpu_notifier(), workqueue_cpu_down_callback() will be called during boot to do nothing, and the memory of workqueue_cpu_down_callback() and gcwq_unbind_fn() will be discarded after boot. If we use hotcpu_notifier(), we can avoid the no-op call of workqueue_cpu_down_callback() and the memory of workqueue_cpu_down_callback() and gcwq_unbind_fn() will be discard at build time: $ ls -l kernel/workqueue.o.cpu_notifier kernel/workqueue.o.hotcpu_notifier -rw-rw-r-- 1 laijs laijs 484080 Sep 15 11:31 kernel/workqueue.o.cpu_notifier -rw-rw-r-- 1 laijs laijs 478240 Sep 15 11:31 kernel/workqueue.o.hotcpu_notifier $ size kernel/workqueue.o.cpu_notifier kernel/workqueue.o.hotcpu_notifier text data bss dec hex filename 18513 2387 1221 22121 5669 kernel/workqueue.o.cpu_notifier 18082 2355 1221 21658 549a kernel/workqueue.o.hotcpu_notifier tj: Updated description. Signed-off-by: Lai Jiangshan Signed-off-by: Tejun Heo

workqueue: use cpuinit instead of devinit for cpu callbacks

2012-09-18T16:59:23Z

For workqueue hotplug callbacks, it makes less sense to use __devinit which discards the memory after boot if !HOTPLUG. __cpuinit, which discards the memory after boot if !HOTPLUG_CPU fits better. tj: Updated description. Signed-off-by: Lai Jiangshan Signed-off-by: Tejun Heo