[PATCH 3.13 068/212] workqueue: fix bugs in wq_update_unbound_numa() failure path

[Kamal Mostafa]

3.13.11.4 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Daeseok Youn <daeseok.youn at gmail.com>

commit 77f300b198f93328c26191b52655ce1b62e202cf upstream.

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.

Signed-off-by: Daeseok Youn <daeseok.youn at gmail.com>
Acked-by: Lai Jiangshan <laijs at cn.fujitsu.com>
Signed-off-by: Tejun Heo <tj at kernel.org>
Fixes: 4c16bd327c74 ("workqueue: implement NUMA affinity for unbound workqueues")
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 kernel/workqueue.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index a8381cf..6b1b746 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -4093,7 +4093,8 @@ static void wq_update_unbound_numa(struct workqueue_struct *wq, int cpu,
 	if (!pwq) {
 		pr_warning("workqueue: allocation failed while updating NUMA affinity of \"%s\"\n",
 			   wq->name);
-		goto out_unlock;
+		mutex_lock(&wq->mutex);
+		goto use_dfl_pwq;
 	}
 
 	/*
-- 
1.9.1