From: Alan Stern <stern@rowland.harvard.edu>
To: Bart Van Assche <bvanassche@acm.org>
Cc: Martin Kepplinger <martin.kepplinger@puri.sm>,
jejb@linux.ibm.com, Can Guo <cang@codeaurora.org>,
martin.petersen@oracle.com, linux-scsi@vger.kernel.org,
linux-kernel@vger.kernel.org, kernel@puri.sm
Subject: Re: [PATCH] scsi: sd: add runtime pm to open / release
Date: Tue, 30 Jun 2020 15:38:02 -0400 [thread overview]
Message-ID: <20200630193802.GA463609@rowland.harvard.edu> (raw)
In-Reply-To: <1804723c-4aaf-a820-d3ef-e70125017cad@acm.org>
On Tue, Jun 30, 2020 at 12:23:12PM -0700, Bart Van Assche wrote:
> On 2020-06-30 11:02, Alan Stern wrote:
> > Right now there doesn't seem to be any mechanism for resuming the queue
> > if an REQ_PREEMPT request is added while the queue is suspended.
>
> I do not agree with the above statement. My understanding is that resuming
> happens as follows if a request is submitted against a runtime suspended
> queue owned by a SCSI LLD:
>
> blk_queue_enter()
> -> blk_pm_request_resume()
Assume that BLK_MQ_REQ_PREEMPT is set in flags. Then where exactly
does blk_queue_enter(q, flags) call blk_pm_request_resume(q)?
Nowhere, as far as I can see.
Alan Stern
> -> pm_request_resume(dev)
> -> __pm_runtime_resume(dev, RPM_ASYNC)
> -> rpm_resume(dev, RPM_ASYNC)
> -> dev->power.request = RPM_REQ_RESUME;
> -> queue_work(pm_wq, &dev->power.work)
> -> pm_runtime_work()
> -> rpm_resume(dev, RPM_NOWAIT)
> -> callback = scsi_runtime_resume;
> -> rpm_callback(callback, dev);
> -> scsi_runtime_resume(dev);
> -> sdev_runtime_resume(dev);
> -> blk_pre_runtime_resume(sdev->request_queue);
> -> q->rpm_status = RPM_RESUMING;
> -> sd_resume(dev);
> -> sd_start_stop_device(sdkp);
> -> sd_pm_ops.runtime_resume == scsi_execute(sdp, START);
> -> blk_get_request(..., ..., BLK_MQ_REQ_PREEMPT)
> -> blk_mq_alloc_request()
> -> blk_queue_enter()
> -> __blk_mq_alloc_request()
> -> blk_execute_rq()
> -> blk_put_request()
> -> blk_post_runtime_resume(sdev->request_queue);
> -> q->rpm_status = RPM_ACTIVE;
> -> pm_runtime_mark_last_busy(q->dev);
> -> pm_request_autosuspend(q->dev);
>
> Bart.
next prev parent reply other threads:[~2020-06-30 19:38 UTC|newest]
Thread overview: 68+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-23 11:10 [PATCH] scsi: sd: add runtime pm to open / release Martin Kepplinger
2020-06-24 13:33 ` Bart Van Assche
2020-06-25 8:16 ` Martin Kepplinger
2020-06-25 14:52 ` Alan Stern
2020-06-26 3:53 ` Bart Van Assche
2020-06-26 15:07 ` Bart Van Assche
2020-06-26 15:44 ` Alan Stern
2020-06-28 2:37 ` Bart Van Assche
2020-06-28 13:10 ` Alan Stern
2020-06-29 9:42 ` Martin Kepplinger
2020-06-29 16:15 ` Alan Stern
2020-06-29 16:56 ` Bart Van Assche
2020-06-29 17:40 ` Alan Stern
2020-06-30 3:33 ` Martin Kepplinger
2020-06-30 13:38 ` Alan Stern
2020-06-30 15:59 ` Bart Van Assche
2020-06-30 18:02 ` Alan Stern
2020-06-30 19:23 ` Bart Van Assche
2020-06-30 19:38 ` Alan Stern [this message]
2020-06-30 23:31 ` Bart Van Assche
2020-07-01 0:49 ` Alan Stern
2020-07-06 16:41 ` Alan Stern
2020-07-28 7:02 ` Martin Kepplinger
2020-07-28 20:02 ` Alan Stern
2020-07-29 14:12 ` Martin Kepplinger
2020-07-29 14:32 ` Alan Stern
2020-07-29 14:44 ` Martin K. Petersen
2020-07-29 14:56 ` Alan Stern
2020-07-29 14:46 ` James Bottomley
2020-07-29 14:53 ` James Bottomley
2020-07-29 15:40 ` Martin Kepplinger
2020-07-29 15:44 ` James Bottomley
2020-07-29 16:43 ` Martin Kepplinger
2020-07-29 18:25 ` Alan Stern
2020-07-29 18:29 ` James Bottomley
2020-07-30 8:52 ` Martin Kepplinger
2020-07-30 8:54 ` Martin Kepplinger
2020-07-30 15:10 ` Alan Stern
2020-08-04 9:39 ` Martin Kepplinger
2020-08-07 9:51 ` Martin Kepplinger
2020-08-07 14:30 ` Alan Stern
2020-08-08 6:59 ` Martin Kepplinger
2020-08-08 15:05 ` Alan Stern
2020-08-09 9:20 ` Martin Kepplinger
2020-08-09 15:26 ` Alan Stern
2020-08-10 12:03 ` Martin Kepplinger
2020-08-10 14:13 ` Alan Stern
2020-08-11 7:55 ` Martin Kepplinger
2020-08-11 13:48 ` Alan Stern
2020-08-23 14:57 ` [PATCH] block: Fix bug in runtime-resume handling Alan Stern
2020-08-24 17:48 ` Bart Van Assche
2020-08-24 20:13 ` Alan Stern
2020-08-26 7:48 ` Martin Kepplinger
2020-08-27 17:42 ` Martin Kepplinger
2020-08-27 20:29 ` Alan Stern
2020-08-29 7:24 ` Martin Kepplinger
2020-08-29 15:26 ` Alan Stern
2020-08-29 16:33 ` Martin Kepplinger
2020-08-29 18:56 ` Alan Stern
2020-08-30 0:38 ` Bart Van Assche
2020-08-30 1:06 ` Alan Stern
2020-07-29 15:40 ` [PATCH] scsi: sd: add runtime pm to open / release Alan Stern
2020-07-29 15:49 ` James Bottomley
2020-07-29 16:17 ` Alan Stern
2020-07-29 15:52 ` Martin Kepplinger
2020-07-29 18:10 ` Douglas Gilbert
2020-07-30 8:05 ` Martin Kepplinger
2020-07-30 15:14 ` Alan Stern
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