Commit a7cfa0af authored by Yu Kuai's avatar Yu Kuai Committed by Jens Axboe
Browse files

blk-ioc: fix recursive spin_lock/unlock_irq() in ioc_clear_queue() 



Recursive spin_lock/unlock_irq() is not safe, because spin_unlock_irq()
will enable irq unconditionally:

spin_lock_irq	queue_lock	-> disable irq
spin_lock_irq	ioc->lock
spin_unlock_irq ioc->lock	-> enable irq
/*
 * AA dead lock will be triggered if current context is preempted by irq,
 * and irq try to hold queue_lock again.
 */
spin_unlock_irq queue_lock

Fix this problem by using spin_lock/unlock() directly for 'ioc->lock'.

Fixes: 5a0ac57c ("blk-ioc: protect ioc_destroy_icq() by 'queue_lock'")
Signed-off-by: default avatarYu Kuai <yukuai3@huawei.com>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20230606011438.3743440-1-yukuai1@huaweicloud.com


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent f12bc113

block/blk-ioc.c

+2 −2
Original line number Diff line number Diff line
@@ -179,9 +179,9 @@ void ioc_clear_queue(struct request_queue *q) 
		 * Other context won't hold ioc lock to wait for queue_lock, see

		 * details in ioc_release_fn().

		 */

		spin_lock_irq(&icq->ioc->lock);

		spin_lock(&icq->ioc->lock);

		ioc_destroy_icq(icq);

		spin_unlock_irq(&icq->ioc->lock);

		spin_unlock(&icq->ioc->lock);

	}

	spin_unlock_irq(&q->queue_lock);

}