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SubjectRe: [PATCH V3] workqueue: fix double unlock bug
On Tue, Apr 15, 2014 at 08:17:43AM +0900, Daeseok Youn wrote:
>
> Use default pwq when alloc_unbound_pwq() is failed.
>
> And remove "if" condition for whether "pwq" is same as "wq->dfl_pwq"
> when wq_calc_node_cpumask() returns false and just use "goto use_dfl_pwq"
>
> Signed-off-by: Daeseok Youn <daeseok.youn@gmail.com>

This is an awfully inadequate patch description. Can you change it to
something like the following?

workqueue: fix bugs in wq_update_unbound_numa() failure path

wq_update_unbound_numa() failure path has the following two bugs.

* alloc_unbound_pwq() is called without holding wq->mutex; however, if
the allocation fails, it jumps to out_unlock which tries to unlock
wq->mutex.

* The function should switch to dfl_pwq on failure but didn't do so
after alloc_unbound_pwq() failure.

Fix it by regrabbing wq->mutex and jumping to use_dfl_pwq on
alloc_unbound_pwq() failure.


> diff --git a/kernel/workqueue.c b/kernel/workqueue.c
> index 0ee63af..0679854 100644
> --- a/kernel/workqueue.c
> +++ b/kernel/workqueue.c
> @@ -4087,10 +4087,7 @@ static void wq_update_unbound_numa(struct workqueue_struct *wq, int cpu,
> if (cpumask_equal(cpumask, pwq->pool->attrs->cpumask))
> goto out_unlock;
> } else {
> - if (pwq == wq->dfl_pwq)
> - goto out_unlock;
> - else
> - goto use_dfl_pwq;
> + goto use_dfl_pwq;

And please put this in a separate patch. Patches which are to be
backported through -stable should be minimal. Also, please update the
comment above to reflect the change.

Thanks.

--
tejun


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