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| author | Tejun Heo <tj@kernel.org> | 2012-08-08 09:38:42 -0700 |
|---|---|---|
| committer | Tejun Heo <tj@kernel.org> | 2012-08-13 16:27:55 -0700 |
| commit | 1265057fa02c7bed3b6d9ddc8a2048065a370364 (patch) | |
| tree | b10e631ca6157103fcc71188e972b06e18c3570f /kernel/workqueue.c | |
| parent | 41f63c5359d14ca995172b8f6eaffd93f60fec54 (diff) | |
| download | lwn-1265057fa02c7bed3b6d9ddc8a2048065a370364.tar.gz lwn-1265057fa02c7bed3b6d9ddc8a2048065a370364.zip | |
workqueue: fix CPU binding of flush_delayed_work[_sync]()
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>
Diffstat (limited to 'kernel/workqueue.c')
| -rw-r--r-- | kernel/workqueue.c | 7 |
1 files changed, 4 insertions, 3 deletions
diff --git a/kernel/workqueue.c b/kernel/workqueue.c index 41ae2c0979fe..11723c5b2b20 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -1319,7 +1319,7 @@ void delayed_work_timer_fn(unsigned long __data) struct cpu_workqueue_struct *cwq = get_work_cwq(&dwork->work); local_irq_disable(); - __queue_work(WORK_CPU_UNBOUND, cwq->wq, &dwork->work); + __queue_work(dwork->cpu, cwq->wq, &dwork->work); local_irq_enable(); } EXPORT_SYMBOL_GPL(delayed_work_timer_fn); @@ -1356,6 +1356,7 @@ static void __queue_delayed_work(int cpu, struct workqueue_struct *wq, set_work_cwq(work, get_cwq(lcpu, wq), 0); + dwork->cpu = cpu; timer->expires = jiffies + delay; if (unlikely(cpu != WORK_CPU_UNBOUND)) @@ -2997,7 +2998,7 @@ bool flush_delayed_work(struct delayed_work *dwork) { local_irq_disable(); if (del_timer_sync(&dwork->timer)) - __queue_work(WORK_CPU_UNBOUND, + __queue_work(dwork->cpu, get_work_cwq(&dwork->work)->wq, &dwork->work); local_irq_enable(); return flush_work(&dwork->work); @@ -3020,7 +3021,7 @@ bool flush_delayed_work_sync(struct delayed_work *dwork) { local_irq_disable(); if (del_timer_sync(&dwork->timer)) - __queue_work(WORK_CPU_UNBOUND, + __queue_work(dwork->cpu, get_work_cwq(&dwork->work)->wq, &dwork->work); local_irq_enable(); return flush_work_sync(&dwork->work); |