From: Frederic Weisbecker <frederic@xxxxxxxxxx>
[ Upstream commit 406dd42bd1ba0c01babf9cde169bb319e52f6147 ]
When an itimer deactivates a previously armed expiration, it simply doesn't
do anything. As a result the process wide cputime counter keeps running and
the tick dependency stays set until it reaches the old ghost expiration
value.
This can be reproduced with the following snippet:
void trigger_process_counter(void)
{
struct itimerval n = {};
n.it_value.tv_sec = 100;
setitimer(ITIMER_VIRTUAL, &n, NULL);
n.it_value.tv_sec = 0;
setitimer(ITIMER_VIRTUAL, &n, NULL);
}
Fix this with resetting the relevant base expiration. This is similar to
disarming a timer.
Signed-off-by: Frederic Weisbecker <frederic@xxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Acked-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20210726125513.271824-4-frederic@xxxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
kernel/time/posix-cpu-timers.c | 2 --
1 file changed, 2 deletions(-)
diff --git a/kernel/time/posix-cpu-timers.c b/kernel/time/posix-cpu-timers.c
index eacb0ca30193..30e061b210b7 100644
--- a/kernel/time/posix-cpu-timers.c
+++ b/kernel/time/posix-cpu-timers.c
@@ -1201,8 +1201,6 @@ void set_process_cpu_timer(struct task_struct *tsk, unsigned int clkid,
}
}
- if (!*newval)
- return;
*newval += now;
}
--
2.30.2
