[PATCHv3 1/1] kernel/power/autosleep.c: check for pm_suspend() return before queueing suspend again

[Nitish Ambastha <nitish.a@samsung.com>]

Prevent tight loop for suspend-resume when some
devices failed to suspend
If some devices failed to suspend, we monitor this
error in try_to_suspend(). pm_suspend() is already
an 'int' returning function, how about checking return
from pm_suspend() before queueing suspend again?

For devices which do not register for pending events,
this will prevent tight loop for suspend-resume in
suspend abort scenarios due to device suspend failures

Signed-off-by: Nitish Ambastha <nitish.a@samsung.com>
---
v2: Rearranged code to make wait entry shared with
    existing one as suggested by Pavel Machek <pavel@ucw.cz>
    Corrected log level from pr_info to pr_err for failure log
    Added return check for hibernate()

v3: Restructured code as suggested by Rafael J Wysocki <rjw@rjwysocki.net>

 kernel/power/autosleep.c |   20 +++++++++-----------
 1 file changed, 9 insertions(+), 11 deletions(-)

diff --git a/kernel/power/autosleep.c b/kernel/power/autosleep.c
index 9012ecf..e458d0c 100644
--- a/kernel/power/autosleep.c
+++ b/kernel/power/autosleep.c
@@ -26,6 +26,7 @@ static struct wakeup_source *autosleep_ws;
 static void try_to_suspend(struct work_struct *work)
 {
 	unsigned int initial_count, final_count;
+	int error;
 
 	if (!pm_get_wakeup_count(&initial_count, true))
 		goto out;
@@ -42,23 +43,20 @@ static void try_to_suspend(struct work_struct *work)
 		mutex_unlock(&autosleep_lock);
 		return;
 	}
-	if (autosleep_state >= PM_SUSPEND_MAX)
-		hibernate();
-	else
-		pm_suspend(autosleep_state);
 
-	mutex_unlock(&autosleep_lock);
+	error = autosleep_state < PM_SUSPEND_MAX ?
+		pm_suspend(autosleep_state) : hibernate();
 
-	if (!pm_get_wakeup_count(&final_count, false))
-		goto out;
+	mutex_unlock(&autosleep_lock);
 
 	/*
-	 * If the wakeup occured for an unknown reason, wait to prevent the
-	 * system from trying to suspend and waking up in a tight loop.
+	 * If some devices failed to suspend or if the wakeup ocurred
+	 * for an unknown reason, wait to prevent the system from
+	 * trying to suspend and waking up in a tight loop.
 	 */
-	if (final_count == initial_count)
+	if (error || (pm_get_wakeup_count(&final_count, false)
+		&& (final_count == initial_count)))
 		schedule_timeout_uninterruptible(HZ / 2);
-
  out:
 	queue_up_suspend_work();
 }
-- 
1.7.9.5