diff options
| author | Thomas Tuttle <ttuttle@chromium.org> | 2011-09-14 16:22:28 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2011-10-03 11:40:31 -0700 |
| commit | d5b1a08d0d0a73c716766275eb0c5648e143ca85 (patch) | |
| tree | 2f62c1aa34c268658ca29b6776fdb73b71fcc7e9 | |
| parent | c780713f786ee22532839502ed35f1bd1cb0fd1d (diff) | |
workqueue: lock cwq access in drain_workqueue
commit fa2563e41c3d6d6e8af437643981ed28ae0cb56d upstream.
Take cwq->gcwq->lock to avoid racing between drain_workqueue checking to
make sure the workqueues are empty and cwq_dec_nr_in_flight decrementing
and then incrementing nr_active when it activates a delayed work.
We discovered this when a corner case in one of our drivers resulted in
us trying to destroy a workqueue in which the remaining work would
always requeue itself again in the same workqueue. We would hit this
race condition and trip the BUG_ON on workqueue.c:3080.
Signed-off-by: Thomas Tuttle <ttuttle@chromium.org>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
| -rw-r--r-- | kernel/workqueue.c | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/kernel/workqueue.c b/kernel/workqueue.c index 0400553f0d04..aec02b6a1c4a 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -3026,8 +3026,13 @@ reflush: for_each_cwq_cpu(cpu, wq) { struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); + bool drained; - if (!cwq->nr_active && list_empty(&cwq->delayed_works)) + spin_lock_irq(&cwq->gcwq->lock); + drained = !cwq->nr_active && list_empty(&cwq->delayed_works); + spin_unlock_irq(&cwq->gcwq->lock); + + if (drained) continue; if (++flush_cnt == 10 || |