kgdb: clocksource watchdog

In order to not trip the clocksource watchdog, kgdb must touch the
clocksource watchdog on the return to normal system run state.
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

include/linux/clocksource.h

@@ -216,6 +216,7 @@ static inline void clocksource_calculate_interval(struct clocksource *c,
 /* used to install a new clocksource */
 extern int clocksource_register(struct clocksource*);
 extern void clocksource_unregister(struct clocksource*);
+extern void clocksource_touch_watchdog(void);
 extern struct clocksource* clocksource_get_next(void);
 extern void clocksource_change_rating(struct clocksource *cs, int rating);
 extern void clocksource_resume(void);

kernel/kgdb.c

@@ -28,6 +28,7 @@
  * kind, whether express or implied.
  */
 #include <linux/pid_namespace.h>
+#include <linux/clocksource.h>
 #include <linux/interrupt.h>
 #include <linux/spinlock.h>
 #include <linux/console.h>
@@ -574,6 +575,7 @@ static void kgdb_wait(struct pt_regs *regs)
 
 	/* Signal the primary CPU that we are done: */
 	atomic_set(&cpu_in_kgdb[cpu], 0);
+	clocksource_touch_watchdog();
 	local_irq_restore(flags);
 }
 #endif
@@ -1396,6 +1398,7 @@ kgdb_handle_exception(int evector, int signo, int ecode, struct pt_regs *regs)
 	    atomic_read(&kgdb_cpu_doing_single_step) != cpu) {
 
 		atomic_set(&kgdb_active, -1);
+		clocksource_touch_watchdog();
 		local_irq_restore(flags);
 
 		goto acquirelock;
@@ -1487,6 +1490,7 @@ kgdb_handle_exception(int evector, int signo, int ecode, struct pt_regs *regs)
 kgdb_restore:
 	/* Free kgdb_active */
 	atomic_set(&kgdb_active, -1);
+	clocksource_touch_watchdog();
 	local_irq_restore(flags);
 
 	return error;

kernel/time/clocksource.c

@@ -221,6 +221,18 @@ void clocksource_resume(void)
 	spin_unlock_irqrestore(&clocksource_lock, flags);
 }
 
+/**
+ * clocksource_touch_watchdog - Update watchdog
+ *
+ * Update the watchdog after exception contexts such as kgdb so as not
+ * to incorrectly trip the watchdog.
+ *
+ */
+void clocksource_touch_watchdog(void)
+{
+	clocksource_resume_watchdog();
+}
+
 /**
  * clocksource_get_next - Returns the selected clocksource
  *