block, bfq: remove wrong lock in bfq_requests_merged

In bfq_requests_merged(), there is a deadlock because the lock on
bfqq->bfqd->lock is held by the calling function, but the code of
this function tries to grab the lock again.

This deadlock is currently hidden by another bug (fixed by next commit
for this source file), which causes the body of bfq_requests_merged()
to be never executed.

This commit removes the deadlock by removing the lock/unlock pair.

Signed-off-by: Filippo Muzzini <filippo.muzzini@outlook.it>
Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c
index b622e73a326ad7163cdf938425c75fb9c9e1cade..02dd4c836936caab7087095a558e1d770e965511 100644 (file)
--- a/block/bfq-iosched.c
+++ b/block/bfq-iosched.c
@@ -1847,7 +1847,6 @@ static void bfq_requests_merged(struct request_queue *q, struct request *rq,
 
        if (!RB_EMPTY_NODE(&rq->rb_node))
                goto end;
-       spin_lock_irq(&bfqq->bfqd->lock);
 
        /*
         * If next and rq belong to the same bfq_queue and next is older
@@ -1872,7 +1871,6 @@ static void bfq_requests_merged(struct request_queue *q, struct request *rq,
        bfq_remove_request(q, next);
        bfqg_stats_update_io_remove(bfqq_group(bfqq), next->cmd_flags);
 
-       spin_unlock_irq(&bfqq->bfqd->lock);
 end:
        bfqg_stats_update_io_merged(bfqq_group(bfqq), next->cmd_flags);
 }