Commit 0c92a655 authored Apr 23, 2022 by Nicholas Piggin Committed by sanglipeng Feb 23, 2024

timers/nohz: Switch to ONESHOT_STOPPED in the low-res handler when the tick is stopped

stable inclusion
from stable-v5.10.193
commit b2125926ba6665a2d84b4a09e7dd2807aeafa145
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I9399M

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=b2125926ba6665a2d84b4a09e7dd2807aeafa145



--------------------------------

commit 62c1256d upstream.

When tick_nohz_stop_tick() stops the tick and high resolution timers are
disabled, then the clock event device is not put into ONESHOT_STOPPED
mode. This can lead to spurious timer interrupts with some clock event
device drivers that don't shut down entirely after firing.

Eliminate these by putting the device into ONESHOT_STOPPED mode at points
where it is not being reprogrammed. When there are no timers active, then
tick_program_event() with KTIME_MAX can be used to stop the device. When
there is a timer active, the device can be stopped at the next tick (any
new timer added by timers will reprogram the tick).

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20220422141446.915024-1-npiggin@gmail.com


Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: sanglipeng <sanglipeng1@jd.com>

parent 40feb022

kernel/time/tick-sched.c

+10 −2

Original line number	Diff line number	Diff line
		@@ -927,6 +927,8 @@ static void tick_nohz_stop_tick(struct tick_sched *ts, int cpu)
		if (unlikely(expires == KTIME_MAX)) {
		if (ts->nohz_mode == NOHZ_MODE_HIGHRES)
		hrtimer_cancel(&ts->sched_timer);
		else
		tick_program_event(KTIME_MAX, 1);
		return;
		}

		@@ -1329,9 +1331,15 @@ static void tick_nohz_handler(struct clock_event_device *dev)
		tick_sched_do_timer(ts, now);
		tick_sched_handle(ts, regs);

		/* No need to reprogram if we are running tickless */
		if (unlikely(ts->tick_stopped))
		if (unlikely(ts->tick_stopped)) {
		/*
		* The clockevent device is not reprogrammed, so change the
		* clock event device to ONESHOT_STOPPED to avoid spurious
		* interrupts on devices which might not be truly one shot.
		*/
		tick_program_event(KTIME_MAX, 1);
		return;
		}

		hrtimer_forward(&ts->sched_timer, now, TICK_NSEC);
		tick_program_event(hrtimer_get_expires(&ts->sched_timer), 1);