From: Tejun Heo <tj@kernel.org>
Date: Tue, 21 Aug 2012 20:18:24 +0000 (-0700)
Subject: workqueue: reimplement cancel_delayed_work() using try_to_grab_pending()
X-Git-Tag: omap-for-v3.7-rc1/fixes-cpufreq-signed~52^2~13
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=57b30ae77bf00d2318df711ef9a4d2a9be0a3a2a;p=pandora-kernel.git

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>
---

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