PM / reboot: Eliminate race between reboot and suspend

At present, "systemctl suspend" and "shutdown" can run in parrallel. A
system can suspend after devices_shutdown(), and resume. Then the shutdown
task goes on to power off. This causes many devices are not really shut
off. Hence replacing reboot_mutex with system_transition_mutex (renamed
from pm_mutex) to achieve the exclusion. The renaming of pm_mutex as
system_transition_mutex can be better to reflect the purpose of the mutex.

Signed-off-by: Pingfan Liu <kernelfans@gmail.com>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

1 files changed, 6 insertions, 6 deletions

diff --git a/kernel/power/main.c b/kernel/power/main.c
index d9706da10930..35b50823d83b 100644
--- a/kernel/power/main.c
+++ b/kernel/power/main.c
@@ -15,17 +15,16 @@
 #include <linux/workqueue.h>
 #include <linux/debugfs.h>
 #include <linux/seq_file.h>
+#include <linux/suspend.h>
 
 #include "power.h"
 
-DEFINE_MUTEX(pm_mutex);
-
 #ifdef CONFIG_PM_SLEEP
 
 void lock_system_sleep(void)
 {
 	current->flags |= PF_FREEZER_SKIP;
-	mutex_lock(&pm_mutex);
+	mutex_lock(&system_transition_mutex);
 }
 EXPORT_SYMBOL_GPL(lock_system_sleep);
 
@@ -37,8 +36,9 @@ void unlock_system_sleep(void)
 	 *
 	 * Reason:
 	 * Fundamentally, we just don't need it, because freezing condition
-	 * doesn't come into effect until we release the pm_mutex lock,
-	 * since the freezer always works with pm_mutex held.
+	 * doesn't come into effect until we release the
+	 * system_transition_mutex lock, since the freezer always works with
+	 * system_transition_mutex held.
 	 *
 	 * More importantly, in the case of hibernation,
 	 * unlock_system_sleep() gets called in snapshot_read() and
@@ -47,7 +47,7 @@ void unlock_system_sleep(void)
 	 * enter the refrigerator, thus causing hibernation to lockup.
 	 */
 	current->flags &= ~PF_FREEZER_SKIP;
-	mutex_unlock(&pm_mutex);
+	mutex_unlock(&system_transition_mutex);
 }
 EXPORT_SYMBOL_GPL(unlock_system_sleep);