On RT the timer can be preempted while running and therefore we wait with timer_wait_for_callback() for the timer to complete (instead of busy looping). The RCU-readlock is held to ensure that this posix timer is not removed while we wait on it. If the timer is removed then it invokes call_rcu() with a pointer that is shared with the hrtimer because it is part of the same union. In order to avoid any possible side effects I am moving the rcu pointer out of the union.
Cc: [email protected] Signed-off-by: Sebastian Andrzej Siewior <[email protected]> --- include/linux/posix-timers.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/include/linux/posix-timers.h b/include/linux/posix-timers.h index 672c4f32311e..4754eb4298b1 100644 --- a/include/linux/posix-timers.h +++ b/include/linux/posix-timers.h @@ -101,8 +101,8 @@ struct k_itimer { struct { struct alarm alarmtimer; } alarm; - struct rcu_head rcu; } it; + struct rcu_head rcu; }; void run_posix_cpu_timers(struct task_struct *task); -- 2.16.3
