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Date:   Thu, 4 Apr 2019 14:57:27 +0800
From:   Ming Lei <ming.lei@redhat.com>
To:     Bart Van Assche <bvanassche@acm.org>
Cc:     Jens Axboe <axboe@kernel.dk>, linux-block@vger.kernel.org,
        Dongli Zhang <dongli.zhang@oracle.com>,
        James Smart <james.smart@broadcom.com>,
        Bart Van Assche <bart.vanassche@wdc.com>,
        linux-scsi@vger.kernel.org,
        "Martin K . Petersen" <martin.petersen@oracle.com>,
        Christoph Hellwig <hch@lst.de>,
        "James E . J . Bottomley" <jejb@linux.vnet.ibm.com>,
        jianchao wang <jianchao.w.wang@oracle.com>
Subject: Re: [PATCH V3 1/6] blk-mq: grab .q_usage_counter when queuing
 request from plug code path
Message-ID: <20190404065725.GC5004@ming.t460p>
References: <20190403102609.18707-1-ming.lei@redhat.com>
 <20190403102609.18707-2-ming.lei@redhat.com>
 <1554304871.118779.185.camel@acm.org>
 <20190403162726.GB22741@ming.t460p>
 <1554326574.118779.235.camel@acm.org>
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On Wed, Apr 03, 2019 at 02:22:54PM -0700, Bart Van Assche wrote:
> On Thu, 2019-04-04 at 00:27 +0800, Ming Lei wrote:
> > blk_mq_flush_plug_list():
> > 	blk_mq_sched_insert_requests()
> > 		insert requests to sw queue or scheduler queue 
> > 		blk_mq_run_hw_queue
> > 
> > Because of concurrent run queue, all requests inserted above may be completed
> > before calling the above blk_mq_run_hw_queue. Then queue can be freed
> > during the above blk_mq_run_hw_queue().
> 
> Thanks for the clarification. That makes sense to me.

I guess it is helpful for review to add the above description in comment log,
will do that in V4.

Thanks,
Ming