clocksource: fix lock order in the resume path

lockdep complains about the lock nesting of clocksource and watchdog lock
in the resume path.

Change the resume marker to a bit operation and remove the lock from this
path.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: john stultz <johnstul@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c
index 3db5c3c..51b6a6a 100644 (file)
--- a/kernel/time/clocksource.c
+++ b/kernel/time/clocksource.c
@@ -74,7 +74,7 @@ static struct clocksource *watchdog;
 static struct timer_list watchdog_timer;
 static DEFINE_SPINLOCK(watchdog_lock);
 static cycle_t watchdog_last;
-static int watchdog_resumed;
+static unsigned long watchdog_resumed;
 
 /*
  * Interval: 0.5sec Threshold: 0.0625s
@@ -104,9 +104,7 @@ static void clocksource_watchdog(unsigned long data)
 
        spin_lock(&watchdog_lock);
 
-       resumed = watchdog_resumed;
-       if (unlikely(resumed))
-               watchdog_resumed = 0;
+       resumed = test_and_clear_bit(0, &watchdog_resumed);
 
        wdnow = watchdog->read();
        wd_nsec = cyc2ns(watchdog, (wdnow - watchdog_last) & watchdog->mask);
@@ -151,9 +149,7 @@ static void clocksource_watchdog(unsigned long data)
 }
 static void clocksource_resume_watchdog(void)
 {
-       spin_lock(&watchdog_lock);
-       watchdog_resumed = 1;
-       spin_unlock(&watchdog_lock);
+       set_bit(0, &watchdog_resumed);
 }
 
 static void clocksource_check_watchdog(struct clocksource *cs)