3.4-stable review patch. If anyone has any objections, please let me know.
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From: Viresh Kumar viresh.kumar@linaro.org
commit 84ea7fe37908254c3bd90910921f6e1045c1747a upstream.
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... Signed-off-by: Thomas Gleixner tglx@linutronix.de Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- kernel/hrtimer.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)
--- a/kernel/hrtimer.c +++ b/kernel/hrtimer.c @@ -985,11 +985,8 @@ int __hrtimer_start_range_ns(struct hrti /* 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 @@ -1004,6 +1001,9 @@ int __hrtimer_start_range_ns(struct hrti
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);