| Message ID | 20200706151436.GA702867@rowland.harvard.edu (mailing list archive) |
|---|---|
| State | Mainlined |
| Commit | 8f38f8e0a30e1c33cdfc48eba2bd63ac2eae373a |
| Headers | show |
| Series | [v3] SCSI and block: Simplify resume handling | expand |
On 2020-07-06 08:14, Alan Stern wrote: > 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 <stern@rowland.harvard.edu> > CC: Can Guo <cang@codeaurora.org> > CC: Bart Van Assche <bvanassche@acm.org> This patch looks good to me. Can, since this patch modifies code in which you recently fixed a bug, would it be possible to test this patch? Thanks, Bart.
> This patch looks good to me. Can, since this patch modifies code in > which you recently fixed a bug, would it be possible to test this > patch? Can: Please verify Alan's patch: https://patchwork.kernel.org/patch/11646029/ Bart: A proper review tag would be appreciated. Thanks!
On 2020-07-06 08:14, Alan Stern wrote: > 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. Reviewed-by: Bart Van Assche <bvanassche@acm.org>
On Mon, 6 Jul 2020 11:14:36 -0400, Alan Stern wrote: > 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. > > [...] Applied to 5.9/scsi-queue, thanks! [1/1] scsi: block: pm: Simplify resume handling https://git.kernel.org/mkp/scsi/c/8f38f8e0a30e
Index: usb-devel/block/blk-pm.c =================================================================== --- usb-devel.orig/block/blk-pm.c +++ usb-devel/block/blk-pm.c @@ -164,9 +164,8 @@ 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. @@ -175,19 +174,13 @@ void blk_post_runtime_resume(struct requ { 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); + blk_set_runtime_active(q); } else { + 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 +197,25 @@ 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) { - spin_lock_irq(&q->queue_lock); - q->rpm_status = RPM_ACTIVE; - pm_runtime_mark_last_busy(q->dev); - pm_request_autosuspend(q->dev); - spin_unlock_irq(&q->queue_lock); - } + int old_status; + + if (!q->dev) + return; + + 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); } }
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 <stern@rowland.harvard.edu> CC: Can Guo <cang@codeaurora.org> CC: Bart Van Assche <bvanassche@acm.org> --- v3: Arrange the code in blk_pm_post_runtime_resume() and blk_set_runtime_active() so that the "if (!q->dev)" tests and early returns come first, as in the other nearby functions. 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. [as1939c] block/blk-pm.c | 41 ++++++++++++++++++++++------------------- drivers/scsi/scsi_pm.c | 10 ++-------- 2 files changed, 24 insertions(+), 27 deletions(-)