4.17-stable review patch. If anyone has any objections, please let me know.
------------------ From: Filippo Muzzini <[email protected]> [ 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 <[email protected]> Signed-off-by: Paolo Valente <[email protected]> Signed-off-by: Jens Axboe <[email protected]> Signed-off-by: Sasha Levin <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- block/bfq-iosched.c | 2 -- 1 file changed, 2 deletions(-) --- a/block/bfq-iosched.c +++ b/block/bfq-iosched.c @@ -1898,7 +1898,6 @@ static void bfq_requests_merged(struct r 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 @@ -1923,7 +1922,6 @@ static void bfq_requests_merged(struct r 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); }
