itimers: Handle relative timers with CONFIG_TIME_LOW_RES proper

commit 51cbb5242a41700a3f250ecfb48dcfb7e4375ea4 upstream.

As Helge reported for timerfd we have the same issue in itimers. We return
remaining time larger than the programmed relative time to user space in case
of CONFIG_TIME_LOW_RES=y. Use the proper function to adjust the extra time
added in hrtimer_start_range_ns().

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Helge Deller <deller@gmx.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: linux-m68k@lists.linux-m68k.org
Cc: dhowells@redhat.com
Link: http://lkml.kernel.org/r/20160114164159.528222587@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
[bwh: Backported to 3.2: adjust filename]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/kernel/itimer.c b/kernel/itimer.c
index d802883..c6f9489 100644 (file)
--- a/kernel/itimer.c
+++ b/kernel/itimer.c
@@ -26,7 +26,7 @@
  */
 static struct timeval itimer_get_remtime(struct hrtimer *timer)
 {
-       ktime_t rem = hrtimer_get_remaining(timer);
+       ktime_t rem = __hrtimer_get_remaining(timer, true);
 
        /*
         * Racy but safe: if the itimer expires after the above