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authorTejun Heo <tj@kernel.org>2012-08-21 13:18:24 -0700
committerTejun Heo <tj@kernel.org>2012-08-21 13:18:24 -0700
commit57b30ae77bf00d2318df711ef9a4d2a9be0a3a2a (patch)
treed6e084bf0e2b82bb39302ee0e94e6f3f04762dbc /kernel/workqueue.c
parente7c2f967445dd2041f0f8e3179cca22bb8bb7f79 (diff)
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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.c30
1 files changed, 30 insertions, 0 deletions
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index b394df8..039d0fa 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
*
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