[PATCH 2/3] workqueue: extend wq_pool_mutex to also protect pwq-installation

[Lai Jiangshan]

Athough pwq-installation without wq_pool_mutex held is not bug,
but it is not good design, it is better to make the pwq-allocation and installation
are in the (same) wq_pool_mutex.

And since the pwq-allocation and installation are in the same wq_pool_mutex,
get_online_cpus() will not be needed for this reason, and it will be remove
in later patch.

Signed-off-by: Lai Jiangshan <laijs@xxxxxxxxxxxxxx>
---
 kernel/workqueue.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 7a217f0..9bc3a87 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -3805,8 +3805,6 @@ int apply_workqueue_attrs(struct workqueue_struct *wq,
 		}
 	}
 
-	mutex_unlock(&wq_pool_mutex);
-
 	/* all pwqs have been created successfully, let's install'em */
 	mutex_lock(&wq->mutex);
 
@@ -3827,6 +3825,8 @@ int apply_workqueue_attrs(struct workqueue_struct *wq,
 		put_pwq_unlocked(pwq_tbl[node]);
 	put_pwq_unlocked(dfl_pwq);
 
+	mutex_unlock(&wq_pool_mutex);
+
 	put_online_cpus();
 	ret = 0;
 	/* fall through */
-- 
1.7.4.4

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