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:
5a0ac57c48aa ("blk-ioc: protect ioc_destroy_icq() by 'queue_lock'")
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20230606011438.3743440-1-yukuai1@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
* 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);
}