user/sven/linux.git/include/linux/workqueue.h, branch v3.18.108

workqueue: Fix flag collision

2017-09-13T21:03:46Z

commit fbf1c41fc0f4d3574ac2377245efd666c1fa3075 upstream. Commit 0a94efb5acbb ("workqueue: implicit ordered attribute should be overridable") introduced a __WQ_ORDERED_EXPLICIT flag but gave it the same value as __WQ_LEGACY. I don't believe these were intended to mean the same thing, so renumber __WQ_ORDERED_EXPLICIT. Fixes: 0a94efb5acbb ("workqueue: implicit ordered attribute should be ...") Signed-off-by: Ben Hutchings Signed-off-by: Tejun Heo Signed-off-by: Greg Kroah-Hartman

workqueue: implicit ordered attribute should be overridable

2017-08-11T16:30:16Z

commit 0a94efb5acbb6980d7c9ab604372d93cd507e4d8 upstream. 5c0338c68706 ("workqueue: restore WQ_UNBOUND/max_active==1 to be ordered") automatically enabled ordered attribute for unbound workqueues w/ max_active == 1. Because ordered workqueues reject max_active and some attribute changes, this implicit ordered mode broke cases where the user creates an unbound workqueue w/ max_active == 1 and later explicitly changes the related attributes. This patch distinguishes explicit and implicit ordered setting and overrides from attribute changes if implict. Signed-off-by: Tejun Heo Fixes: 5c0338c68706 ("workqueue: restore WQ_UNBOUND/max_active==1 to be ordered") Cc: Holger Hoffstätte Signed-off-by: Greg Kroah-Hartman

workqueue: fix hang involving racing cancel[_delayed]_work_sync()'s for PREEMPT_NONE

2015-03-28T13:37:48Z

[ Upstream commit 8603e1b30027f943cc9c1eef2b291d42c3347af1 ] 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 Reported-by: Rabin Vincent Cc: Tomeu Vizoso Cc: stable@vger.kernel.org Tested-by: Jesper Nilsson Tested-by: Rabin Vincent Signed-off-by: Sasha Levin

workqueue: apply __WQ_ORDERED to create_singlethread_workqueue()

2014-09-12T20:13:08Z

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. 8719dceae2f9 ("workqueue: reject adjusting max_active or applying attrs to ordered workqueues") introduced __WQ_ORDERED to protect ordered workqueues against dynamic attribute changes which can break ordering guarantees but forgot to apply it to create_singlethread_workqueue(). This in itself is okay as nobody currently uses dynamic attribute change on workqueues created with create_singlethread_workqueue(). However, 4c16bd327c ("workqueue: implement NUMA affinity for unbound workqueues") broke singlethreaded guarantee for ordered workqueues through allocating a separate pool_workqueue on each NUMA node by default. A later change 8a2b75384444 ("workqueue: fix ordered workqueues in NUMA setups") fixed it by allocating only one global pool_workqueue if __WQ_ORDERED is set. Combined, the __WQ_ORDERED omission in create_singlethread_workqueue() became critical breaking its single threadedness and ordering guarantee. Let's make create_singlethread_workqueue() wrap alloc_ordered_workqueue() instead so that it inherits __WQ_ORDERED and can implicitly track future ordered_workqueue changes. v2: I missed that __WQ_ORDERED now protects against pwq splitting across NUMA nodes and incorrectly described the patch as a nice-to-have fix to protect against future dynamic attribute usages. Oleg pointed out that this is actually a critical breakage due to 8a2b75384444 ("workqueue: fix ordered workqueues in NUMA setups"). Signed-off-by: Tejun Heo Reported-by: Mike Anderson Cc: Oleg Nesterov Cc: Gustavo Luiz Duarte Cc: Tomas Henzl Cc: stable@vger.kernel.org Fixes: 4c16bd327c ("workqueue: implement NUMA affinity for unbound workqueues")

workqueue: remove unused work_clear_pending()

2014-05-22T15:35:51Z

In 8930caba3dbd ("workqueue: disable irq while manipulating PENDING"), setting last CPU and clearing PENDING got merged into a single operation (set_work_cpu_and_clear_pending()), which resulted that the internal routine work_clear_pending() is not used any more. tj: Minor description tweak. Signed-off-by: Lai Jiangshan Signed-off-by: Tejun Heo

workqueue: remove unused WORK_CPU_END

2014-05-22T15:35:51Z

WORK_CPU_END is totally unused since 4e8b22bd1a37 ("workqueue: fix pool ID allocation leakage and remove BUILD_BUG_ON() in init_workqueues"). It should be removed. After it is removed, the comment "special cpu IDs" is not precise due to there is only one special CPU ID (WORK_CPU_UNBOUND) left, so we also change this comment to the description for WORK_CPU_UNBOUND. tj: Minor description and comment tweaks. Signed-off-by: Lai Jiangshan Signed-off-by: Tejun Heo

workqueue: declare system_highpri_wq

2014-05-22T15:35:50Z

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 Signed-off-by: Tejun Heo

workqueue: Remove deprecated system_nrt[_freezable]_wq

2014-05-14T17:11:41Z

system_nrt[_freezable]_wq were deprecated by 3b07e9c ("workqueue: deprecate system_nrt[_freezable]_wq") and have been deprecated for a long time. In addition, these are not used anymore. So, let's remove these functions. Signed-off-by: Jingoo Han Signed-off-by: Tejun Heo

workqueue: Remove deprecated flush[_delayed]_work_sync()

2014-05-14T17:11:23Z

flush[_delayed]_work_sync() were deprecated by 4382973 ("workqueue: deprecate flush[_delayed]_work_sync()") and have been deprecated for a long time. In addition, these are not used anymore. So, let's remove these functions. Signed-off-by: Jingoo Han Signed-off-by: Tejun Heo

Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2014-04-01T18:00:07Z

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 ...