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block, bfq: remove wrong lock in bfq_requests_merged

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[ Upstream commit a12bffebc0c9d6a5851f062aaea3aa7c4adc6042 ]

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>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Filippo Muzzini 2018-05-31 15:23:11 +02:00 committed by Greg Kroah-Hartman
parent 67226fb52c
commit 63019044fb
1 changed files with 0 additions and 2 deletions
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2
block/bfq-iosched.c
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@ -1678,7 +1678,6 @@ 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
@ -1702,7 +1701,6 @@ static void bfq_requests_merged(struct request_queue *q, struct request *rq,
bfq_remove_request(q, next);
spin_unlock_irq(&bfqq->bfqd->lock);
end:
bfqg_stats_update_io_merged(bfqq_group(bfqq), next->cmd_flags);
}