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Commit 3d492c2e authored by Omar Sandoval's avatar Omar Sandoval Committed by Jens Axboe
Browse files

blk-mq-sched: don't hold queue_lock when calling exit_icq 



None of the other blk-mq elevator hooks are called with this lock held.
Additionally, it can lead to circular locking dependencies between
queue_lock and the private scheduler lock.

Reported-by: default avatarPaolo Valente <paolo.valente@linaro.org>
Signed-off-by: default avatarOmar Sandoval <osandov@fb.com>
Signed-off-by: default avatarJens Axboe <axboe@fb.com>
parent f6f94300

block/blk-ioc.c

+16 −6
Original line number Diff line number Diff line
@@ -35,7 +35,10 @@ static void icq_free_icq_rcu(struct rcu_head *head) 
	kmem_cache_free(icq->__rcu_icq_cache, icq);

}



/* Exit an icq. Called with both ioc and q locked. */

/*

 * Exit an icq. Called with both ioc and q locked for sq, only ioc locked for

 * mq.

 */

static void ioc_exit_icq(struct io_cq *icq)

{

	struct elevator_type *et = icq->q->elevator->type;
@@ -166,6 +169,7 @@ EXPORT_SYMBOL(put_io_context); 
 */

void put_io_context_active(struct io_context *ioc)

{

	struct elevator_type *et;

	unsigned long flags;

	struct io_cq *icq;
@@ -184,6 +188,11 @@ void put_io_context_active(struct io_context *ioc) 
	hlist_for_each_entry(icq, &ioc->icq_list, ioc_node) {

		if (icq->flags & ICQ_EXITED)

			continue;



		et = icq->q->elevator->type;

		if (et->uses_mq) {

			ioc_exit_icq(icq);

		} else {

			if (spin_trylock(icq->q->queue_lock)) {

				ioc_exit_icq(icq);

				spin_unlock(icq->q->queue_lock);
@@ -193,6 +202,7 @@ void put_io_context_active(struct io_context *ioc) 
				goto retry;

			}

		}

	}

	spin_unlock_irqrestore(&ioc->lock, flags);



	put_io_context(ioc);