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| author | Thomas Tuttle <ttuttle@chromium.org> | 2011-09-14 16:22:28 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2011-09-14 18:09:38 -0700 |
| commit | fa2563e41c3d6d6e8af437643981ed28ae0cb56d (patch) | |
| tree | 7d0dbcc4214a3bceb4d1dd9251df88752c1313b5 /kernel/workqueue.c | |
| parent | df4e33ad249b7480d6ba5dd11fc1dac5cfaffce1 (diff) | |
| download | lwn-fa2563e41c3d6d6e8af437643981ed28ae0cb56d.tar.gz lwn-fa2563e41c3d6d6e8af437643981ed28ae0cb56d.zip | |
workqueue: lock cwq access in drain_workqueue
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>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel/workqueue.c')
| -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 25fb1b0e53fa..1783aabc6128 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -2412,8 +2412,13 @@ 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 || |