PM / Runtime: Use deferred_resume flag in pm_request_resume

This patch (as1307) adds a small optimization to
__pm_request_resume().  If the device is currently being suspended,
there's no need to queue a work routine to resume it.  Setting the
deferred_resume flag will suffice.  (There's also a minor improvement
to the function's code layout: An unnecessary "else" is removed.)

Also, the patch clarifies the usage of the deferred_resume flag.  It
is meaningful only while a suspend is in progress, so it should be
cleared just before a suspend starts, not just after one ends.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>

drivers/base/power/runtime.c

@@ -185,6 +185,7 @@ int __pm_runtime_suspend(struct device *dev, bool from_wq)
 	}
 
 	dev->power.runtime_status = RPM_SUSPENDING;
+	dev->power.deferred_resume = false;
 
 	if (dev->bus && dev->bus->pm && dev->bus->pm->runtime_suspend) {
 		spin_unlock_irq(&dev->power.lock);
@@ -200,7 +201,6 @@ int __pm_runtime_suspend(struct device *dev, bool from_wq)
 	if (retval) {
 		dev->power.runtime_status = RPM_ACTIVE;
 		pm_runtime_cancel_pending(dev);
-		dev->power.deferred_resume = false;
 
 		if (retval == -EAGAIN || retval == -EBUSY) {
 			notify = true;
@@ -217,7 +217,6 @@ int __pm_runtime_suspend(struct device *dev, bool from_wq)
 	wake_up_all(&dev->power.wait_queue);
 
 	if (dev->power.deferred_resume) {
-		dev->power.deferred_resume = false;
 		__pm_runtime_resume(dev, false);
 		retval = -EAGAIN;
 		goto out;
@@ -659,13 +658,17 @@ static int __pm_request_resume(struct device *dev)
 
 	pm_runtime_deactivate_timer(dev);
 
+	if (dev->power.runtime_status == RPM_SUSPENDING) {
+		dev->power.deferred_resume = true;
+		return retval;
+	}
 	if (dev->power.request_pending) {
 		/* If non-resume request is pending, we can overtake it. */
 		dev->power.request = retval ? RPM_REQ_NONE : RPM_REQ_RESUME;
 		return retval;
-	} else if (retval) {
-		return retval;
 	}
+	if (retval)
+		return retval;
 
 	dev->power.request = RPM_REQ_RESUME;
 	dev->power.request_pending = true;