| From | Greg Kroah-Hartman <> | Subject | [PATCH 5.14 011/334] posix-cpu-timers: Force next expiration recalc after itimer reset | Date | Mon, 13 Sep 2021 15:11:05 +0200 |
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From: Frederic Weisbecker <frederic@kernel.org>
[ 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@kernel.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/20210726125513.271824-4-frederic@kernel.org Signed-off-by: Sasha Levin <sashal@kernel.org> --- 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 517be7fd175e..a002685f688d 100644 --- a/kernel/time/posix-cpu-timers.c +++ b/kernel/time/posix-cpu-timers.c @@ -1346,8 +1346,6 @@ void set_process_cpu_timer(struct task_struct *tsk, unsigned int clkid, } } - if (!*newval) - return; *newval += now; } -- 2.30.2
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