[PATCH] fix vsyscall settimeofday

I've only seen this on x86_64.

The vsyscall state only gets updated when a timer interrupts comes in.  So
if the time is set long before the next timer, there will be a period when
a gettimeofday() won't reflect the correct time.

I added an explicit update_vsyscall() during the settimeofday(), that way
the vsyscall state doesn't get stale.

Signed-off-by: Daniel Walker <dwalker@mvista.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Ingo Molnar <mingo@elte.hu>
Acked-by: John Stultz <johnstul@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

kernel/timer.c

@@ -862,6 +862,8 @@ int do_settimeofday(struct timespec *tv)
 	clock->error = 0;
 	ntp_clear();
 
+	update_vsyscall(&xtime, clock);
+
 	write_sequnlock_irqrestore(&xtime_lock, flags);
 
 	/* signal hrtimers about time change */