From patchwork Wed Jul 1 18:37:18 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alan Stern X-Patchwork-Id: 11637095 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id B63D8161F for ; Wed, 1 Jul 2020 18:37:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A828B20853 for ; Wed, 1 Jul 2020 18:37:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728193AbgGAShV (ORCPT ); Wed, 1 Jul 2020 14:37:21 -0400 Received: from netrider.rowland.org ([192.131.102.5]:34369 "HELO netrider.rowland.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1725440AbgGAShU (ORCPT ); Wed, 1 Jul 2020 14:37:20 -0400 Received: (qmail 508077 invoked by uid 1000); 1 Jul 2020 14:37:18 -0400 Date: Wed, 1 Jul 2020 14:37:18 -0400 From: Alan Stern To: Bart Van Assche , martin.petersen@oracle.com Cc: Can Guo , linux-scsi@vger.kernel.org, linux-block@vger.kernel.org Subject: [PATCH v2] SCSI and block: Simplify resume handling Message-ID: <20200701183718.GA507293@rowland.harvard.edu> MIME-Version: 1.0 Content-Disposition: inline User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-scsi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-scsi@vger.kernel.org Commit 05d18ae1cc8a ("scsi: pm: Balance pm_only counter of request queue during system resume") fixed a problem in the block layer's runtime-PM code: blk_set_runtime_active() failed to call blk_clear_pm_only(). However, the commit's implementation was awkward; it forced the SCSI system-resume handler to choose whether to call blk_post_runtime_resume() or blk_set_runtime_active(), depending on whether or not the SCSI device had previously been runtime suspended. This patch simplifies the situation considerably by adding the missing function call directly into blk_set_runtime_active() (under the condition that the queue is not already in the RPM_ACTIVE state). This allows the SCSI routine to revert back to its original form. Furthermore, making this change reveals that blk_post_runtime_resume() (in its success pathway) does exactly the same thing as blk_set_runtime_active(). The duplicate code is easily removed by making one routine call the other. No functional changes are intended. Signed-off-by: Alan Stern CC: Can Guo CC: Bart Van Assche --- v2: Don't call blk_clear_pm_only() if the queue's RPM status was already set to RPM_ACTIVE. This happens during a system resume if the device was not in runtime suspend beforehand. Martin: Since you merged the oritinal 05d18ae1cc8a commit, I'm submitting this to you as an update. If you would prefer to have it go by way of the block-layer tree, let me know and I'll resend it. [as1939b] block/blk-pm.c | 30 +++++++++++++++--------------- drivers/scsi/scsi_pm.c | 10 ++-------- 2 files changed, 17 insertions(+), 23 deletions(-) Index: usb-devel/block/blk-pm.c =================================================================== --- usb-devel.orig/block/blk-pm.c +++ usb-devel/block/blk-pm.c @@ -164,30 +164,21 @@ EXPORT_SYMBOL(blk_pre_runtime_resume); * * Description: * Update the queue's runtime status according to the return value of the - * device's runtime_resume function. If it is successfully resumed, process - * the requests that are queued into the device's queue when it is resuming - * and then mark last busy and initiate autosuspend for it. + * device's runtime_resume function. If the resume was successful, call + * blk_set_runtime_active() to do the real work of restarting the queue. * * This function should be called near the end of the device's * runtime_resume callback. */ void blk_post_runtime_resume(struct request_queue *q, int err) { - if (!q->dev) - return; - - spin_lock_irq(&q->queue_lock); if (!err) { - q->rpm_status = RPM_ACTIVE; - pm_runtime_mark_last_busy(q->dev); - pm_request_autosuspend(q->dev); - } else { + blk_set_runtime_active(q); + } else if (q->dev) { + spin_lock_irq(&q->queue_lock); q->rpm_status = RPM_SUSPENDED; + spin_unlock_irq(&q->queue_lock); } - spin_unlock_irq(&q->queue_lock); - - if (!err) - blk_clear_pm_only(q); } EXPORT_SYMBOL(blk_post_runtime_resume); @@ -204,15 +195,24 @@ EXPORT_SYMBOL(blk_post_runtime_resume); * This function can be used in driver's resume hook to correct queue * runtime PM status and re-enable peeking requests from the queue. It * should be called before first request is added to the queue. + * + * This function is also called by blk_post_runtime_resume() for successful + * runtime resumes. It does everything necessary to restart the queue. */ void blk_set_runtime_active(struct request_queue *q) { if (q->dev) { + int old_status; + spin_lock_irq(&q->queue_lock); + old_status = q->rpm_status; q->rpm_status = RPM_ACTIVE; pm_runtime_mark_last_busy(q->dev); pm_request_autosuspend(q->dev); spin_unlock_irq(&q->queue_lock); + + if (old_status != RPM_ACTIVE) + blk_clear_pm_only(q); } } EXPORT_SYMBOL(blk_set_runtime_active); Index: usb-devel/drivers/scsi/scsi_pm.c =================================================================== --- usb-devel.orig/drivers/scsi/scsi_pm.c +++ usb-devel/drivers/scsi/scsi_pm.c @@ -80,10 +80,6 @@ static int scsi_dev_type_resume(struct d dev_dbg(dev, "scsi resume: %d\n", err); if (err == 0) { - bool was_runtime_suspended; - - was_runtime_suspended = pm_runtime_suspended(dev); - pm_runtime_disable(dev); err = pm_runtime_set_active(dev); pm_runtime_enable(dev); @@ -97,10 +93,8 @@ static int scsi_dev_type_resume(struct d */ if (!err && scsi_is_sdev_device(dev)) { struct scsi_device *sdev = to_scsi_device(dev); - if (was_runtime_suspended) - blk_post_runtime_resume(sdev->request_queue, 0); - else - blk_set_runtime_active(sdev->request_queue); + + blk_set_runtime_active(sdev->request_queue); } }