diff options
author | Tejun Heo <tj@kernel.org> | 2012-08-21 13:18:24 -0700 |
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committer | Tejun Heo <tj@kernel.org> | 2012-08-21 13:18:24 -0700 |
commit | 57b30ae77bf00d2318df711ef9a4d2a9be0a3a2a (patch) | |
tree | d6e084bf0e2b82bb39302ee0e94e6f3f04762dbc /kernel/workqueue.c | |
parent | e7c2f967445dd2041f0f8e3179cca22bb8bb7f79 (diff) |
workqueue: reimplement cancel_delayed_work() using try_to_grab_pending()
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>
Diffstat (limited to 'kernel/workqueue.c')
-rw-r--r-- | kernel/workqueue.c | 30 |
1 files changed, 30 insertions, 0 deletions
diff --git a/kernel/workqueue.c b/kernel/workqueue.c index b394df8beae..039d0fae171 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -2949,6 +2949,36 @@ bool flush_delayed_work(struct delayed_work *dwork) EXPORT_SYMBOL(flush_delayed_work); /** + * cancel_delayed_work - cancel a delayed work + * @dwork: delayed_work to cancel + * + * Kill off a pending delayed_work. Returns %true if @dwork was pending + * and canceled; %false if wasn't pending. Note that the work callback + * function may still be running on return, unless it returns %true and the + * work doesn't re-arm itself. Explicitly flush or use + * cancel_delayed_work_sync() to wait on it. + * + * This function is safe to call from any context including IRQ handler. + */ +bool cancel_delayed_work(struct delayed_work *dwork) +{ + unsigned long flags; + int ret; + + do { + ret = try_to_grab_pending(&dwork->work, true, &flags); + } while (unlikely(ret == -EAGAIN)); + + if (unlikely(ret < 0)) + return false; + + set_work_cpu_and_clear_pending(&dwork->work, work_cpu(&dwork->work)); + local_irq_restore(flags); + return true; +} +EXPORT_SYMBOL(cancel_delayed_work); + +/** * cancel_delayed_work_sync - cancel a delayed work and wait for it to finish * @dwork: the delayed work cancel * |