PM / Sleep: avoid 'autosleep' in shutdown progress

Prevent automatic system suspend from happening during system
shutdown by making try_to_suspend() check system_state and return
immediately if it is not SYSTEM_RUNNING.

This prevents the following breakage from happening (scenario from
Zhang Yanmin):

 Kernel starts shutdown and calls all device driver's shutdown
 callback.  When a driver's shutdown is called, the last wakelock is
 released and suspend-to-ram starts.  However, as some driver's shut
 down callbacks already shut down devices and disabled runtime pm,
 the suspend-to-ram calls driver's suspend callback without noticing
 that device is already off and causes crash.

[rjw: Changelog]
Signed-off-by: Liu ShuoX <[email protected]>
Cc: 3.5+ <[email protected]>
Signed-off-by: Rafael J. Wysocki <[email protected]>

Author: Liu ShuoX

kernel/power/autosleep.c

@@ -32,7 +32,8 @@ static void try_to_suspend(struct work_struct *work)
 
 	mutex_lock(&autosleep_lock);
 
-	if (!pm_save_wakeup_count(initial_count)) {
+	if (!pm_save_wakeup_count(initial_count) ||
+		system_state != SYSTEM_RUNNING) {
 		mutex_unlock(&autosleep_lock);
 		goto out;
 	}