hrtimer_start*() family never fails to enqueue a hrtimer to a clock-base. The only special case is when the hrtimer was in past. If it is getting enqueued to local CPUs's clock-base, we raise a softirq and exit, else we handle that on next interrupt on remote CPU.
At several places in the kernel, we try to make sure if hrtimer was added properly or not by calling hrtimer_active(), like:
hrtimer_start(timer, expires, mode); if (hrtimer_active(timer)) { /* Added successfully */ } else { /* Was added in the past */ }
As hrtimer_start*() never fails, hrtimer_active() is guaranteed to return '1'. So, there is no point calling hrtimer_active().
This patch updates rtmutex core to get this fixed.
Cc: Ingo Molnar mingo@redhat.com Cc: Peter Zijlstra peterz@infradead.org Signed-off-by: Viresh Kumar viresh.kumar@linaro.org --- kernel/locking/rtmutex.c | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-)
diff --git a/kernel/locking/rtmutex.c b/kernel/locking/rtmutex.c index fc60594..9ea8830 100644 --- a/kernel/locking/rtmutex.c +++ b/kernel/locking/rtmutex.c @@ -922,11 +922,8 @@ rt_mutex_slowlock(struct rt_mutex *lock, int state, set_current_state(state);
/* Setup the timer, when timeout != NULL */ - if (unlikely(timeout)) { + if (unlikely(timeout)) hrtimer_start_expires(&timeout->timer, HRTIMER_MODE_ABS); - if (!hrtimer_active(&timeout->timer)) - timeout->task = NULL; - }
ret = task_blocks_on_rt_mutex(lock, &waiter, current, detect_deadlock);