Re: [PATCH] blk-mq: fix race between complete and BLK_EH_RESET_TIMER

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On Thu, 2018-04-12 at 04:55 +0800, Ming Lei wrote:
> +again:
>  	switch (ret) {
>  	case BLK_EH_HANDLED:
>  		__blk_mq_complete_request(req);
>  		break;
>  	case BLK_EH_RESET_TIMER:
>  		[ ... ]
> +		spin_lock_irqsave(req->q->queue_lock, flags);
> +		if (blk_mq_rq_state(req) != MQ_RQ_COMPLETE_IN_RESET) {
> +			blk_mq_rq_update_aborted_gstate(req, 0);
> +			blk_add_timer(req);
> +		} else {
> +			blk_mq_rq_update_state(req, MQ_RQ_IN_FLIGHT);
> +			ret = BLK_EH_HANDLED;
> +			goto again;
> +		}
> +		spin_unlock_irqrestore(req->q->queue_lock, flags);

Does the above chunk introduce a backwards goto from inside a region around
which a spinlock is held to outside that region? Can such a goto result in
anything else than a deadlock?

Thanks,

Bart.







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