linux-kernel - Re: [PATCH 5/5] nvme: use __blk_mq_complete

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Date:   Wed, 20 Jun 2018 16:39:56 +0200
From:   Christoph Hellwig <hch@....de>
To:     Jianchao Wang <jianchao.w.wang@...cle.com>
Cc:     axboe@...nel.dk, hch@....de, martin.petersen@...cle.com,
        keith.busch@...el.com, josef@...icpanda.com,
        ulf.hansson@...aro.org, linux-block@...r.kernel.org,
        linux-scsi@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 5/5] nvme: use __blk_mq_complete_request in timeout path

> diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
> index 73a97fc..2a161f6 100644
> --- a/drivers/nvme/host/pci.c
> +++ b/drivers/nvme/host/pci.c
> @@ -1203,6 +1203,7 @@ static enum blk_eh_timer_return nvme_timeout(struct request *req, bool reserved)
>  		nvme_warn_reset(dev, csts);
>  		nvme_dev_disable(dev, false);
>  		nvme_reset_ctrl(&dev->ctrl);
> +		__blk_mq_complete_request(req);
>  		return BLK_EH_DONE;
>  	}
>  
> @@ -1213,6 +1214,11 @@ static enum blk_eh_timer_return nvme_timeout(struct request *req, bool reserved)
>  		dev_warn(dev->ctrl.device,
>  			 "I/O %d QID %d timeout, completion polled\n",
>  			 req->tag, nvmeq->qid);
> +		/*
> +		 * nvme_end_request will invoke blk_mq_complete_request,
> +		 * it will do nothing for this timed out request.
> +		 */
> +		__blk_mq_complete_request(req);

And this clearly is bogus.  We want to iterate over the tagetset
and cancel all requests, not do that manually here.

That was the whole point of the original change.