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Subject[PATCH RT 3/3] posix-timers: move the rcu head out of the union
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.

Signed-off-by: Sebastian Andrzej Siewior <>
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);
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