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Date:   Wed, 20 Mar 2019 17:29:53 +0800
From:   Ming Lei <ming.lei@redhat.com>
To:     "zhengbin (A)" <zhengbin13@huawei.com>
Cc:     axboe@kernel.dk, hch@lst.de, linux-block@vger.kernel.org,
        linux-kernel@vger.kernel.org, houtao1@huawei.com,
        yanaijie@huawei.com, jianchao.w.wang@oracle.com
Subject: Re: [PATCH] blk-mq: fix a hung issue when set device state to
 blocked and restore running
Message-ID: <20190320092951.GA9051@ming.t460p>
References: <1553068921-6605-1-git-send-email-zhengbin13@huawei.com>
 <20190320081110.GA8408@ming.t460p>
 <c0821276-2127-e6d8-97b0-b96628d11ba7@huawei.com>
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On Wed, Mar 20, 2019 at 04:52:40PM +0800, zhengbin (A) wrote:
> Thanks for your quick reply, I will study BLK_STS_DEV_RESOURCE in detail
> 
> > BLK_STS_DEV_RESOURCE means that the driver will rerun hw queue, so
> > maybe you need to investigate why it is returned from scsi driver first.
> because we set the device state to blocked,
> scsi_queue_rq-->prep_to_mq(return BLK_STS_RESOURCE)
> 	     -->out_put_budget  transfer BLK_STS_RESOURCE to BLK_STS_DEV_RESOURCE
> In this situtation, the request does not send to the driver.

Then the queue will be run when the scsi_device becomes un-blocked,
see scsi_internal_device_unblock_nowait().


Thanks,
Ming