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From: "jianchao.wang" <jianchao.w.wang@oracle.com>
To: Hannes Reinecke <hare@suse.de>, axboe@kernel.dk
Cc: linux-block@vger.kernel.org, jsmart2021@gmail.com,
	sagi@grimberg.me, josef@toxicpanda.com,
	linux-nvme@lists.infradead.org, linux-kernel@vger.kernel.org,
	keith.busch@intel.com, jthumshirn@suse.de, hch@lst.de,
	bvanassche@acm.org
Subject: Re: [PATCH V2 8/8] blk-mq: remove blk_mq_tagset_busy_iter
Date: Mon, 25 Mar 2019 15:37:04 +0800	[thread overview]
Message-ID: <f9d22543-65d1-e473-e3ab-deefa2d6e884@oracle.com> (raw)
In-Reply-To: <47fe0e2a-f427-0e3e-e15b-a9e2bffb502f@suse.de>

Hi Hannes

On 3/25/19 3:18 PM, Hannes Reinecke wrote:
> On 3/25/19 6:38 AM, Jianchao Wang wrote:
>> As nobody uses blk_mq_tagset_busy_iter, remove it.
>>
>> Signed-off-by: Jianchao Wang <jianchao.w.wang@oracle.com>
>> ---
>>   block/blk-mq-tag.c     | 95 --------------------------------------------------
>>   include/linux/blk-mq.h |  2 --
>>   2 files changed, 97 deletions(-)
>>
> Please, don't.
> 
> I'm currently implementing reserved commands for SCSI and reworking the SCSI error handling where I rely on this interface quite heavily.


blk_mq_tagset_busy_iter could access some stale requests which maybe freed due to io scheduler switching, request_queue cleanup (shared tagset)
when there is someone submits io and gets driver tag. When io scheduler attached, even quiesce request_queue won't work.

If this patchset is accepted, blk_mq_tagset_busy_iter could be replaced with blk_mq_queue_inflight_tag_iter which needs
to be invoked by every request_queue that shares the tagset.

Please go ahead your work.

Thanks
Jianchao

> 
> Cheers,
> 
> Hannes

  reply	other threads:[~2019-03-25  7:37 UTC|newest]

Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-03-25  5:38 [PATCH V2 0/8]: blk-mq: use static_rqs to iterate busy tags Jianchao Wang
2019-03-25  5:38 ` [PATCH V2 1/8] blk-mq: get rid of the synchronize_rcu in __blk_mq_update_nr_hw_queues Jianchao Wang
2019-03-25  5:38 ` [PATCH V2 2/8] blk-mq: use static_rqs instead of rqs to iterate tags Jianchao Wang
2019-03-25  7:12   ` Dongli Zhang
2019-03-25  7:14     ` jianchao.wang
2019-03-25  5:38 ` [PATCH V2 3/8] blk-mq: use blk_mq_queue_tag_inflight_iter in debugfs Jianchao Wang
2019-03-25  5:38 ` [PATCH V2 4/8] mtip32xx: use blk_mq_queue_tag_inflight_iter Jianchao Wang
2019-03-25  5:38 ` [PATCH V2 5/8] nbd: " Jianchao Wang
2019-03-25  5:38 ` [PATCH V2 6/8] skd: " Jianchao Wang
2019-03-25  5:38 ` [PATCH V2 7/8] nvme: " Jianchao Wang
2019-03-25 13:49   ` Keith Busch
2019-03-26  1:17     ` jianchao.wang
2019-03-26  2:41       ` Ming Lei
2019-03-26  3:05         ` jianchao.wang
2019-03-26 23:57           ` Keith Busch
2019-03-27  2:03             ` jianchao.wang
2019-03-27  2:15               ` Keith Busch
2019-03-27  2:27                 ` jianchao.wang
2019-03-27  2:33                   ` Keith Busch
2019-03-27  2:45                     ` jianchao.wang
2019-03-27  6:51                       ` Keith Busch
2019-03-27  7:18                         ` jianchao.wang
2019-03-25  5:38 ` [PATCH V2 8/8] blk-mq: remove blk_mq_tagset_busy_iter Jianchao Wang
2019-03-25  7:18   ` Hannes Reinecke
2019-03-25  7:37     ` jianchao.wang [this message]
2019-03-25  8:25       ` Hannes Reinecke
2019-03-25  9:12         ` jianchao.wang
2019-03-26 14:17         ` Jens Axboe
  -- strict thread matches above, loose matches on Subject: below --
2019-03-25  5:28 [PATCH V2 0/8]: blk-mq: use static_rqs to iterate busy tags Jianchao Wang
2019-03-25  5:28 ` [PATCH V2 8/8] blk-mq: remove blk_mq_tagset_busy_iter Jianchao Wang

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