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authorPeter Zijlstra <peterz@infradead.org>2015-06-11 14:46:45 +0200
committerThomas Gleixner <tglx@linutronix.de>2015-06-19 00:09:56 +0200
commit8edfb0362e8e52dec2de08fa163af01c9da2c9d0 (patch)
tree5f607cf35b8c625695eb7cc3d357432f733185fa /kernel/time
parentc04dca02bc73096435a5c36efd5ccb2171edcbe1 (diff)
hrtimer: Fix hrtimer_is_queued() hole
A queued hrtimer that gets restarted (hrtimer_start*() while hrtimer_is_queued()) will briefly appear as unqueued/inactive, even though the timer has always been active, we just moved it. Close this hole by preserving timer->state in hrtimer_start_range_ns()'s remove_hrtimer() call. Reported-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: ktkhai@parallels.com Cc: rostedt@goodmis.org Cc: juri.lelli@gmail.com Cc: pang.xunlei@linaro.org Cc: wanpeng.li@linux.intel.com Cc: umgwanakikbuti@gmail.com Link: http://lkml.kernel.org/r/20150611124743.175989138@infradead.org Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'kernel/time')
-rw-r--r--kernel/time/hrtimer.c23
1 files changed, 13 insertions, 10 deletions
diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c
index b1b795e5e0b1..1604157374d7 100644
--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -889,10 +889,10 @@ static void __remove_hrtimer(struct hrtimer *timer,
* remove hrtimer, called with base lock held
*/
static inline int
-remove_hrtimer(struct hrtimer *timer, struct hrtimer_clock_base *base)
+remove_hrtimer(struct hrtimer *timer, struct hrtimer_clock_base *base, bool restart)
{
if (hrtimer_is_queued(timer)) {
- unsigned long state;
+ unsigned long state = timer->state;
int reprogram;
/*
@@ -906,12 +906,15 @@ remove_hrtimer(struct hrtimer *timer, struct hrtimer_clock_base *base)
debug_deactivate(timer);
timer_stats_hrtimer_clear_start_info(timer);
reprogram = base->cpu_base == this_cpu_ptr(&hrtimer_bases);
- /*
- * We must preserve the CALLBACK state flag here,
- * otherwise we could move the timer base in
- * switch_hrtimer_base.
- */
- state = timer->state & HRTIMER_STATE_CALLBACK;
+
+ if (!restart) {
+ /*
+ * We must preserve the CALLBACK state flag here,
+ * otherwise we could move the timer base in
+ * switch_hrtimer_base.
+ */
+ state &= HRTIMER_STATE_CALLBACK;
+ }
__remove_hrtimer(timer, base, state, reprogram);
return 1;
}
@@ -936,7 +939,7 @@ void hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
base = lock_hrtimer_base(timer, &flags);
/* Remove an active timer from the queue: */
- remove_hrtimer(timer, base);
+ remove_hrtimer(timer, base, true);
if (mode & HRTIMER_MODE_REL) {
tim = ktime_add_safe(tim, base->get_time());
@@ -1005,7 +1008,7 @@ int hrtimer_try_to_cancel(struct hrtimer *timer)
base = lock_hrtimer_base(timer, &flags);
if (!hrtimer_callback_running(timer))
- ret = remove_hrtimer(timer, base);
+ ret = remove_hrtimer(timer, base, false);
unlock_hrtimer_base(timer, &flags);