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scsi: block: pm: Simplify resume handling 

Commit 05d18ae1cc ("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.

Link: https://lore.kernel.org/r/20200706151436.GA702867@rowland.harvard.edu
CC: Can Guo <cang@codeaurora.org>
CC: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
This commit is contained in:
Alan Stern 2020-07-06 11:14:36 -04:00 committed by Martin K. Petersen
parent df4ec2fa7a
commit 8f38f8e0a3
2 changed files with 24 additions and 27 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

41
block/blk-pm.c
View File

@ -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 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);
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);

10
drivers/scsi/scsi_pm.c
View File

@ -80,10 +80,6 @@ static int scsi_dev_type_resume(struct device *dev,
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 device *dev,
*/
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);
}
}