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From: Ming Lei <ming.lei@redhat.com>
To: "Martin K. Petersen" <martin.petersen@oracle.com>
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, Christoph Hellwig <hch@lst.de>,
	"James E . J . Bottomley" <jejb@linux.vnet.ibm.com>,
	jianchao wang <jianchao.w.wang@oracle.com>
Subject: Re: [PATCH V5 9/9] SCSI: don't hold device refcount in IO path
Date: Sat, 13 Apr 2019 14:56:09 +0800	[thread overview]
Message-ID: <20190413065608.GA9108@ming.t460p> (raw)
In-Reply-To: <yq1o95akbxj.fsf@oracle.com>

On Fri, Apr 12, 2019 at 08:04:40PM -0400, Martin K. Petersen wrote:
> 
> Ming,
> 
> > scsi_device's refcount is always grabbed in IO path.
> >
> > Turns out it isn't necessary, because blk_queue_cleanup() will
> > drain any in-flight IOs, then cancel timeout/requeue work, and
> > SCSI's requeue_work is canceled too in __scsi_remove_device().
> >
> > Also scsi_device won't go away until blk_cleanup_queue() is done.
> >
> > So don't hold the refcount in IO path, especially the refcount isn't
> > required in IO path since blk_queue_enter() / blk_queue_exit()
> > is introduced in the legacy block layer.
> 
> This all looks good to me. I assume it will go through Jens' tree?
> 
> Acked-by: Martin K. Petersen <martin.petersen@oracle.com>

Hi Nartin,

This patch doesn't depend on patch 1~8, so please take it via scsi tree
if you are fine.


Thanks,
Ming

  reply	other threads:[~2019-04-13  6:57 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-04-12  3:30 [PATCH V5 0/9] blk-mq: fix races related with freeing queue Ming Lei
2019-04-12  3:30 ` [PATCH V5 1/9] blk-mq: grab .q_usage_counter when queuing request from plug code path Ming Lei
2019-04-12  8:20   ` Johannes Thumshirn
2019-04-12 10:55   ` Hannes Reinecke
2019-04-12  3:30 ` [PATCH V5 2/9] blk-mq: move cancel of requeue_work into blk_mq_release Ming Lei
2019-04-12  8:23   ` Johannes Thumshirn
2019-04-12  3:30 ` [PATCH V5 3/9] blk-mq: free hw queue's resource in hctx's release handler Ming Lei
2019-04-12 11:03   ` Hannes Reinecke
2019-04-13  7:18     ` Ming Lei
2019-04-12  3:30 ` [PATCH V5 4/9] blk-mq: move all hctx alloction & initialization into __blk_mq_alloc_and_init_hctx Ming Lei
2019-04-12 11:04   ` Hannes Reinecke
2019-04-12  3:30 ` [PATCH V5 5/9] blk-mq: split blk_mq_alloc_and_init_hctx into two parts Ming Lei
2019-04-12 11:04   ` Hannes Reinecke
2019-04-12  3:30 ` [PATCH V5 6/9] blk-mq: always free hctx after request queue is freed Ming Lei
2019-04-12 11:06   ` Hannes Reinecke
2019-04-13  7:27     ` Ming Lei
2019-04-12  3:30 ` [PATCH V5 7/9] blk-mq: move cancel of hctx->run_work into blk_mq_hw_sysfs_release Ming Lei
2019-04-12 11:08   ` Hannes Reinecke
2019-04-12  3:30 ` [PATCH V5 8/9] block: don't drain in-progress dispatch in blk_cleanup_queue() Ming Lei
2019-04-12 11:09   ` Hannes Reinecke
2019-04-12  3:30 ` [PATCH V5 9/9] SCSI: don't hold device refcount in IO path Ming Lei
2019-04-12 11:09   ` Hannes Reinecke
2019-04-13  0:04   ` Martin K. Petersen
2019-04-13  6:56     ` Ming Lei [this message]
2019-04-13  9:23       ` Ming Lei
2019-04-16  2:12       ` Martin K. Petersen

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