The following commit has been merged into the timers/core branch of tip:
Commit-ID: 62c1256d544747b38e77ca9b5bfe3a26f9592576
Gitweb: https://git.kernel.org/tip/62c1256d544747b38e77ca9b5bfe3a26f9592576
Author: Nicholas Piggin <npiggin@xxxxxxxxx>
AuthorDate: Sat, 23 Apr 2022 00:14:46 +10:00
Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitterDate: Mon, 25 Apr 2022 14:45:22 +02:00
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@xxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20220422141446.915024-1-npiggin@xxxxxxxxx
---
kernel/time/tick-sched.c | 12 ++++++++++--
1 file changed, 10 insertions(+), 2 deletions(-)
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index 2d76c91..b1b105d 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);
|