| Message ID | 20200630151734.GA451991@rowland.harvard.edu (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | SCSI and block: Simplify resume handling | expand |
On Tue, Jun 30, 2020 at 11:17:34AM -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. > > This patch simplifies the situation considerably by adding the missing > function call directly into blk_set_runtime_active(). 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> Please disregard this patch. When I wrote it, I didn't realize that blk_clear_pm_only() is meant to be used like a reference counter (it's a bad choice of name, since the routine does a decrement rather than a clear -- and likewise for blk_set_pm_only()). I'll submit a revised patch later. Alan Stern > block/blk-pm.c | 25 ++++++++++--------------- > drivers/scsi/scsi_pm.c | 10 ++-------- > 2 files changed, 12 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); > > @@ -204,6 +195,9 @@ 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) > { > @@ -213,6 +207,7 @@ void blk_set_runtime_active(struct reque > pm_runtime_mark_last_busy(q->dev); > pm_request_autosuspend(q->dev); > spin_unlock_irq(&q->queue_lock); > + 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); > } > } > >
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); @@ -204,6 +195,9 @@ 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) { @@ -213,6 +207,7 @@ void blk_set_runtime_active(struct reque pm_runtime_mark_last_busy(q->dev); pm_request_autosuspend(q->dev); spin_unlock_irq(&q->queue_lock); + 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(). 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> --- 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. [as1939] block/blk-pm.c | 25 ++++++++++--------------- drivers/scsi/scsi_pm.c | 10 ++-------- 2 files changed, 12 insertions(+), 23 deletions(-)