hrtimer: Set expiry time before switch_hrtimer_base()

switch_hrtimer_base() calls hrtimer_check_target() which ensures that
we do not migrate a timer to a remote cpu if the timer expires before
the current programmed expiry time on that remote cpu.

But __hrtimer_start_range_ns() calls switch_hrtimer_base() before the
new expiry time is set. So the sanity check in hrtimer_check_target()
is operating on stale or even uninitialized data.

Update expiry time before calling switch_hrtimer_base().

[ tglx: Rewrote changelog once again ]

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Cc: linaro-kernel@lists.linaro.org
Cc: linaro-networking@linaro.org
Cc: fweisbec@gmail.com
Cc: arvind.chauhan@arm.com
Link: http://lkml.kernel.org/r/81999e148745fc51bbcd0615823fbab9b2e87e23.1399882253.git.viresh.kumar@linaro.org
Cc: stable@vger.kernel.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c
index 6b715c0af1b117b5b61bd32629a00845f0313557..e0501fe7140d7c97daba3f3438b51272cf6d9932 100644 (file)
--- a/kernel/hrtimer.c
+++ b/kernel/hrtimer.c
@@ -990,11 +990,8 @@ int __hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
        /* Remove an active timer from the queue: */
        ret = remove_hrtimer(timer, base);
 
-       /* Switch the timer base, if necessary: */
-       new_base = switch_hrtimer_base(timer, base, mode & HRTIMER_MODE_PINNED);
-
        if (mode & HRTIMER_MODE_REL) {
-               tim = ktime_add_safe(tim, new_base->get_time());
+               tim = ktime_add_safe(tim, base->get_time());
                /*
                 * CONFIG_TIME_LOW_RES is a temporary way for architectures
                 * to signal that they simply return xtime in
@@ -1009,6 +1006,9 @@ int __hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
 
        hrtimer_set_expires_range_ns(timer, tim, delta_ns);
 
+       /* Switch the timer base, if necessary: */
+       new_base = switch_hrtimer_base(timer, base, mode & HRTIMER_MODE_PINNED);
+
        timer_stats_hrtimer_set_start_info(timer);
 
        leftmost = enqueue_hrtimer(timer, new_base);