Thomas Gleixner f9bd298e3e posix-timers: Prevent RT livelock in itimer_delete() ...

[ Upstream commit 9d9e522010 ]

itimer_delete() has a retry loop when the timer is concurrently expired. On
non-RT kernels this just spin-waits until the timer callback has completed,
except for posix CPU timers which have HAVE_POSIX_CPU_TIMERS_TASK_WORK
enabled.

In that case and on RT kernels the existing task could live lock when
preempting the task which does the timer delivery.

Replace spin_unlock() with an invocation of timer_wait_running() to handle
it the same way as the other retry loops in the posix timer code.

Fixes: ec8f954a40 ("posix-timers: Use a callback for cancel synchronization on PREEMPT_RT")
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://lore.kernel.org/r/87v8g7c50d.ffs@tglx
Signed-off-by: Sasha Levin <sashal@kernel.org>

2023-07-11 19:39:23 +02:00

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