[tip:timers/urgent] posix-timers: Handle relative timers with CONFIG_TIME_LOW_RES proper

[tip-bot for Thomas Gleixner]

Commit-ID:  572c39172684c3711e4a03c9a7380067e2b0661c
Gitweb:     http://git.kernel.org/tip/572c39172684c3711e4a03c9a7380067e2b0661c
Author:     Thomas Gleixner <tglx@xxxxxxxxxxxxx>
AuthorDate: Thu, 14 Jan 2016 16:54:47 +0000
Committer:  Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitDate: Sun, 17 Jan 2016 11:13:55 +0100

posix-timers: Handle relative timers with CONFIG_TIME_LOW_RES proper

As Helge reported for timerfd we have the same issue in posix timers. 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@xxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Helge Deller <deller@xxxxxx>
Cc: John Stultz <john.stultz@xxxxxxxxxx>
Cc: linux-m68k@xxxxxxxxxxxxxxxxxxxx
Cc: dhowells@xxxxxxxxxx
Cc: stable@xxxxxxxxxxxxxxx
Link: http://lkml.kernel.org/r/20160114164159.450510905@xxxxxxxxxxxxx
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
---
 kernel/time/posix-timers.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/time/posix-timers.c b/kernel/time/posix-timers.c
index 31d11ac..f2826c3 100644
--- a/kernel/time/posix-timers.c
+++ b/kernel/time/posix-timers.c
@@ -760,7 +760,7 @@ common_timer_get(struct k_itimer *timr, struct itimerspec *cur_setting)
 	    (timr->it_sigev_notify & ~SIGEV_THREAD_ID) == SIGEV_NONE))
 		timr->it_overrun += (unsigned int) hrtimer_forward(timer, now, iv);
 
-	remaining = ktime_sub(hrtimer_get_expires(timer), now);
+	remaining = __hrtimer_expires_remaining_adjusted(timer, now);
 	/* Return 0 only, when the timer is expired and not pending */
 	if (remaining.tv64 <= 0) {
 		/*