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authorNicholas Piggin <npiggin@gmail.com>2022-04-23 00:14:46 +1000
committerThomas Gleixner <tglx@linutronix.de>2022-04-25 14:45:22 +0200
commit62c1256d544747b38e77ca9b5bfe3a26f9592576 (patch)
tree76b7ac3839b9382128b1a0b69eee7f527d95c77b /kernel/time
parentce8abf340e40e1126bfcb9e7679b3d6b524ae3e0 (diff)
timers/nohz: Switch to ONESHOT_STOPPED in the low-res handler when the tick is stopped
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
Diffstat (limited to 'kernel/time')
-rw-r--r--kernel/time/tick-sched.c12
1 files changed, 10 insertions, 2 deletions
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index 2d76c91b85de..b1b105db31eb 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -928,6 +928,8 @@ 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;
}
@@ -1364,9 +1366,15 @@ 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);