From: Hannes Reinecke <hare@suse.de>
To: Christoph Hellwig <hch@lst.de>, Keith Busch <keith.busch@intel.com>
Cc: Jens Axboe <axboe@kernel.dk>,
linux-nvme@lists.infradead.org, linux-block@vger.kernel.org,
Ming Lei <ming.lei@redhat.com>,
Bart Van Assche <bart.vanassche@wdc.com>
Subject: Re: [RFC PATCH 3/3] blk-mq: Remove generation seqeunce
Date: Wed, 23 May 2018 07:48:47 +0200 [thread overview]
Message-ID: <53b05a82-a3f6-553a-ae3e-6efb8cbe7183@suse.de> (raw)
In-Reply-To: <20180522161704.GA20000@lst.de>
On 05/22/2018 06:17 PM, Christoph Hellwig wrote:
> Hi Keith,
>
> I like this series a lot. One comment that is probably close
> to the big discussion in the thread:
>
>> switch (ret) {
>> case BLK_EH_HANDLED:
>> /*
>> + * If the request is still in flight, the driver is requesting
>> + * blk-mq complete it.
>> */
>> + if (blk_mq_rq_state(req) == MQ_RQ_IN_FLIGHT)
>> + __blk_mq_complete_request(req);
>> + break;
>
> The state check here really irked me, and from the thread it seems like
> I'm not the only one. At least for the NVMe case I think it is perfectly
> safe, although I agree I'd rather audit what other drivers do carefully.
>
> That being said I think BLK_EH_HANDLED seems like a fundamentally broken
> idea, and I'd actually prefer to get rid of it over adding things like
> the MQ_RQ_IN_FLIGHT check above.
>
I can't agree more here.
BLK_EH_HANDLED is breaking all sorts of assumptions, and I'd be glad to
see it go.
> E.g. if we look at the cases where nvme-pci returns it:
>
> - if we did call nvme_dev_disable, we already canceled all requests,
> so we might as well just return BLK_EH_NOT_HANDLED
> - the poll for completion case already completed the command,
> so we should return BLK_EH_NOT_HANDLED
>
> So I think we need to fix up nvme and if needed any other driver
> to return the right value and then assert that the request is
> still in in-flight status for the BLK_EH_HANDLED case.
>
... and then kill BLK_EH_HANDLED :-)
Cheers,
Hannes
WARNING: multiple messages have this Message-ID (diff)
From: hare@suse.de (Hannes Reinecke)
Subject: [RFC PATCH 3/3] blk-mq: Remove generation seqeunce
Date: Wed, 23 May 2018 07:48:47 +0200 [thread overview]
Message-ID: <53b05a82-a3f6-553a-ae3e-6efb8cbe7183@suse.de> (raw)
In-Reply-To: <20180522161704.GA20000@lst.de>
On 05/22/2018 06:17 PM, Christoph Hellwig wrote:
> Hi Keith,
>
> I like this series a lot. One comment that is probably close
> to the big discussion in the thread:
>
>> switch (ret) {
>> case BLK_EH_HANDLED:
>> /*
>> + * If the request is still in flight, the driver is requesting
>> + * blk-mq complete it.
>> */
>> + if (blk_mq_rq_state(req) == MQ_RQ_IN_FLIGHT)
>> + __blk_mq_complete_request(req);
>> + break;
>
> The state check here really irked me, and from the thread it seems like
> I'm not the only one. At least for the NVMe case I think it is perfectly
> safe, although I agree I'd rather audit what other drivers do carefully.
>
> That being said I think BLK_EH_HANDLED seems like a fundamentally broken
> idea, and I'd actually prefer to get rid of it over adding things like
> the MQ_RQ_IN_FLIGHT check above.
>
I can't agree more here.
BLK_EH_HANDLED is breaking all sorts of assumptions, and I'd be glad to
see it go.
> E.g. if we look at the cases where nvme-pci returns it:
>
> - if we did call nvme_dev_disable, we already canceled all requests,
> so we might as well just return BLK_EH_NOT_HANDLED
> - the poll for completion case already completed the command,
> so we should return BLK_EH_NOT_HANDLED
>
> So I think we need to fix up nvme and if needed any other driver
> to return the right value and then assert that the request is
> still in in-flight status for the BLK_EH_HANDLED case.
>
... and then kill BLK_EH_HANDLED :-)
Cheers,
Hannes
next prev parent reply other threads:[~2018-05-23 5:48 UTC|newest]
Thread overview: 128+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-05-21 23:11 [RFC PATCH 0/3] blk-mq: Timeout rework Keith Busch
2018-05-21 23:11 ` Keith Busch
2018-05-21 23:11 ` [RFC PATCH 1/3] blk-mq: Reference count request usage Keith Busch
2018-05-21 23:11 ` Keith Busch
2018-05-22 2:27 ` Ming Lei
2018-05-22 2:27 ` Ming Lei
2018-05-22 15:19 ` Christoph Hellwig
2018-05-22 15:19 ` Christoph Hellwig
2018-05-21 23:11 ` [RFC PATCH 2/3] blk-mq: Fix timeout and state order Keith Busch
2018-05-21 23:11 ` Keith Busch
2018-05-22 2:28 ` Ming Lei
2018-05-22 2:28 ` Ming Lei
2018-05-22 15:24 ` Christoph Hellwig
2018-05-22 15:24 ` Christoph Hellwig
2018-05-22 16:27 ` Bart Van Assche
2018-05-22 16:27 ` Bart Van Assche
2018-05-21 23:11 ` [RFC PATCH 3/3] blk-mq: Remove generation seqeunce Keith Busch
2018-05-21 23:11 ` Keith Busch
2018-05-21 23:29 ` Bart Van Assche
2018-05-21 23:29 ` Bart Van Assche
2018-05-22 14:15 ` Keith Busch
2018-05-22 14:15 ` Keith Busch
2018-05-22 16:29 ` Bart Van Assche
2018-05-22 16:29 ` Bart Van Assche
2018-05-22 16:34 ` Keith Busch
2018-05-22 16:34 ` Keith Busch
2018-05-22 16:48 ` Bart Van Assche
2018-05-22 16:48 ` Bart Van Assche
2018-05-22 2:49 ` Ming Lei
2018-05-22 2:49 ` Ming Lei
2018-05-22 3:16 ` Jens Axboe
2018-05-22 3:16 ` Jens Axboe
2018-05-22 3:47 ` Ming Lei
2018-05-22 3:47 ` Ming Lei
2018-05-22 3:51 ` Jens Axboe
2018-05-22 3:51 ` Jens Axboe
2018-05-22 8:51 ` Ming Lei
2018-05-22 8:51 ` Ming Lei
2018-05-22 14:35 ` Jens Axboe
2018-05-22 14:35 ` Jens Axboe
2018-05-22 14:20 ` Keith Busch
2018-05-22 14:20 ` Keith Busch
2018-05-22 14:37 ` Ming Lei
2018-05-22 14:37 ` Ming Lei
2018-05-22 14:46 ` Keith Busch
2018-05-22 14:46 ` Keith Busch
2018-05-22 14:57 ` Ming Lei
2018-05-22 14:57 ` Ming Lei
2018-05-22 15:01 ` Keith Busch
2018-05-22 15:01 ` Keith Busch
2018-05-22 15:07 ` Ming Lei
2018-05-22 15:07 ` Ming Lei
2018-05-22 15:17 ` Keith Busch
2018-05-22 15:17 ` Keith Busch
2018-05-22 15:23 ` Ming Lei
2018-05-22 15:23 ` Ming Lei
2018-05-22 16:17 ` Christoph Hellwig
2018-05-22 16:17 ` Christoph Hellwig
2018-05-23 0:34 ` Ming Lei
2018-05-23 0:34 ` Ming Lei
2018-05-23 14:35 ` Keith Busch
2018-05-23 14:35 ` Keith Busch
2018-05-24 1:52 ` Ming Lei
2018-05-24 1:52 ` Ming Lei
2018-05-23 5:48 ` Hannes Reinecke [this message]
2018-05-23 5:48 ` Hannes Reinecke
2018-07-12 18:16 ` Bart Van Assche
2018-07-12 18:16 ` Bart Van Assche
2018-07-12 19:24 ` Keith Busch
2018-07-12 19:24 ` Keith Busch
2018-07-12 22:24 ` Bart Van Assche
2018-07-12 22:24 ` Bart Van Assche
2018-07-13 1:12 ` jianchao.wang
2018-07-13 1:12 ` jianchao.wang
2018-07-13 2:40 ` jianchao.wang
2018-07-13 2:40 ` jianchao.wang
2018-07-13 15:43 ` Keith Busch
2018-07-13 15:43 ` Keith Busch
2018-07-13 15:52 ` Bart Van Assche
2018-07-13 15:52 ` Bart Van Assche
2018-07-13 18:47 ` Keith Busch
2018-07-13 18:47 ` Keith Busch
2018-07-13 23:03 ` Bart Van Assche
2018-07-13 23:03 ` Bart Van Assche
2018-07-13 23:58 ` Keith Busch
2018-07-13 23:58 ` Keith Busch
2018-07-18 19:56 ` hch
2018-07-18 19:56 ` hch
2018-07-18 20:39 ` hch
2018-07-18 20:39 ` hch
2018-07-18 21:05 ` Bart Van Assche
2018-07-18 21:05 ` Bart Van Assche
2018-07-18 22:53 ` Keith Busch
2018-07-18 22:53 ` Keith Busch
2018-07-18 20:53 ` Keith Busch
2018-07-18 20:53 ` Keith Busch
2018-07-18 20:58 ` Bart Van Assche
2018-07-18 20:58 ` Bart Van Assche
2018-07-18 21:17 ` Keith Busch
2018-07-18 21:17 ` Keith Busch
2018-07-18 21:30 ` Bart Van Assche
2018-07-18 21:30 ` Bart Van Assche
2018-07-18 21:33 ` Keith Busch
2018-07-18 21:33 ` Keith Busch
2018-07-19 13:19 ` hch
2018-07-19 13:19 ` hch
2018-07-19 14:59 ` Keith Busch
2018-07-19 14:59 ` Keith Busch
2018-07-19 15:56 ` Keith Busch
2018-07-19 15:56 ` Keith Busch
2018-07-19 16:04 ` Bart Van Assche
2018-07-19 16:04 ` Bart Van Assche
2018-07-19 16:22 ` Keith Busch
2018-07-19 16:22 ` Keith Busch
2018-07-19 16:29 ` hch
2018-07-19 16:29 ` hch
2018-07-19 20:18 ` Keith Busch
2018-07-19 20:18 ` Keith Busch
2018-07-19 13:22 ` hch
2018-07-19 13:22 ` hch
2018-05-21 23:29 ` [RFC PATCH 0/3] blk-mq: Timeout rework Bart Van Assche
2018-05-21 23:29 ` Bart Van Assche
2018-05-22 14:06 ` Keith Busch
2018-05-22 14:06 ` Keith Busch
2018-05-22 16:30 ` Bart Van Assche
2018-05-22 16:30 ` Bart Van Assche
2018-05-22 16:44 ` Keith Busch
2018-05-22 16:44 ` Keith Busch
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