[PATCH 3/7] block: Remove sysfs lock from elevator_init_rq()

[Damien Le Moal]

Since elevator_init_rq() is called before the device queue is registered
in sysfs, there is no possible conflict with elevator_switch(). Remove
the unnecessary locking of q->sysfs_lock mutex.

Signed-off-by: Damien Le Moal <damien.lem...@wdc.com>
---
 block/elevator.c | 12 ++----------
 1 file changed, 2 insertions(+), 10 deletions(-)

diff --git a/block/elevator.c b/block/elevator.c
index 7fff06751633..6208ddc334ef 100644
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -617,17 +617,12 @@ void elevator_init_mq(struct request_queue *q)
        if (q->nr_hw_queues != 1)
                return;
 
-       /*
-        * q->sysfs_lock must be held to provide mutual exclusion between
-        * elevator_switch() and here.
-        */
-       mutex_lock(&q->sysfs_lock);
        if (unlikely(q->elevator))
-               goto out_unlock;
+               return;
 
        e = elevator_get(q, "mq-deadline", false);
        if (!e)
-               goto out_unlock;
+               return;
 
        err = blk_mq_init_sched(q, e);
        if (err) {
@@ -635,9 +630,6 @@ void elevator_init_mq(struct request_queue *q)
                        "falling back to \"none\"\n", e->elevator_name);
                elevator_put(e);
        }
-
-out_unlock:
-       mutex_unlock(&q->sysfs_lock);
 }
 
 
-- 
2.21.0