On 8/14/24 4:35 AM, Li Lingfeng wrote:
When interrupt is turned on while a lock holding by spin_lock_irq it
throws a warning because of potential deadlock.
Which tool reported the warning? Please mention this in the patch
description.
blk_mq_mark_tag_wait
spin_lock_irq(&wq->lock)
--> turn off interrupt and get lockA
blk_mq_get_driver_tag
__blk_mq_tag_busy
spin_lock_irq(&tags->lock)
spin_unlock_irq(&tags->lock)
--> release lockB and turn on interrupt accidentally
The above call chain does not match the code in Linus' master tree.
Please fix this.
Fix it by using spin_lock_irqsave to get lockB instead of spin_lock_irq.
Fixes: 4f1731df60f9 ("blk-mq: fix potential io hang by wrong 'wake_batch'")
Signed-off-by: Li Lingfeng <lilingfeng3@xxxxxxxxxx>
Please leave a blank line between the patch description and the section
with tags.
- spin_lock_irq(&tags->lock);
+ spin_lock_irqsave(&tags->lock, flags);
users = tags->active_queues + 1;
WRITE_ONCE(tags->active_queues, users);
blk_mq_update_wake_batch(tags, users);
- spin_unlock_irq(&tags->lock);
+ spin_unlock_irqrestore(&tags->lock, flags);
}
The code changes however look good to me.
Thanks,
Bart.
