[PATCH] clocksource: fix resume logic

We need to make sure that the clocksources are resumed, when timekeeping is
resumed.  The current resume logic does not guarantee this.

Add a resume function pointer to the clocksource struct, so clocksource
drivers which need to reinitialize the clocksource can provide a resume
function.

Add a resume function, which calls the maybe available clocksource resume
functions and resets the watchdog function, so a stable TSC can be used
accross suspend/resume.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Andi Kleen <ak@suse.de>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>

kernel/timer.c

@@ -1903,6 +1903,8 @@ unregister_time_interpolator(struct time_interpolator *ti)
 		prev = &curr->next;
 	}
 
+	clocksource_resume();
+
 	write_seqlock_irqsave(&xtime_lock, flags);
 	if (ti == time_interpolator) {
 		/* we lost the best time-interpolator: */