In switch_hrtimer_base() we are calling hrtimer_check_target() which guarantees this:
/* * With HIGHRES=y we do not migrate the timer when it is expiring * before the next event on the target cpu because we cannot reprogram * the target cpu hardware and we would cause it to fire late. * * Called with cpu_base->lock of target cpu held. */
But switch_hrtimer_base() is only called from one place, i.e. __hrtimer_start_range_ns() and at the point (where we call switch_hrtimer_base()) expiration time is not yet known as we call this routine later:
hrtimer_set_expires_range_ns()
To fix this, we need to find the updated expiry time before calling switch_hrtimer_base() from hrtimer_set_expires_range_ns().
Signed-off-by: Viresh Kumar viresh.kumar@linaro.org --- kernel/hrtimer.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-)
diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c index c712960..81e0251 100644 --- a/kernel/hrtimer.c +++ b/kernel/hrtimer.c @@ -964,11 +964,8 @@ 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 @@ -977,12 +974,15 @@ int __hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim, * timeouts. This will go away with the GTOD framework. */ #ifdef CONFIG_TIME_LOW_RES - tim = ktime_add_safe(tim, new_base->resolution); + tim = ktime_add_safe(tim, base->resolution); #endif }
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); @@ -1000,7 +1000,7 @@ int __hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim, * We need to drop cpu_base->lock to avoid a * lock ordering issue vs. rq->lock. */ - raw_spin_unlock(&new_base->cpu_base->lock); + raw_spin_unlock(&timer->base->cpu_base->lock); raise_softirq_irqoff(HRTIMER_SOFTIRQ); local_irq_restore(flags); return ret;