To avoid getting spurious interrupts on a tickless CPU, clockevent
device can now be stopped by switching to ONESHOT_STOPPED state.
The natural place for handling this transition is tick_program_event().
On 'expires == KTIME_MAX', we skip programming the event and so we need
to fix such call sites as well, to always call tick_program_event()
irrespective of the expires value.
Once the clockevent device is required again, check if it was earlier
put into ONESHOT_STOPPED state. If yes, switch its state to ONESHOT
before programming its event.
To make sure we haven't missed any corner case, add a WARN() for the
case where we try to reprogram clockevent device while we aren't
configured in ONESHOT_STOPPED state.
Signed-off-by: Viresh Kumar <viresh.ku...@linaro.org>
---
kernel/time/clockevents.c | 4 ++++
kernel/time/hrtimer.c | 6 ++----
kernel/time/tick-oneshot.c | 16 ++++++++++++++++
3 files changed, 22 insertions(+), 4 deletions(-)
diff --git a/kernel/time/clockevents.c b/kernel/time/clockevents.c
index 49ed2ea4294c..8ff54495f60b 100644
--- a/kernel/time/clockevents.c
+++ b/kernel/time/clockevents.c
@@ -335,6 +335,10 @@ int clockevents_program_event(struct clock_event_device
*dev, ktime_t expires,
if (dev->state == CLOCK_EVT_STATE_SHUTDOWN)
return 0;
+ /* We must be in ONESHOT state here */
+ WARN_ONCE(dev->state != CLOCK_EVT_STATE_ONESHOT, "Current state: %d\n",
+ dev->state);
+
/* Shortcut for clockevent devices that can deal with ktime. */
if (dev->features & CLOCK_EVT_FEAT_KTIME)
return dev->set_next_ktime(expires, dev);
diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c
index 721d29b99d10..d1be3eda83fa 100644
--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -543,8 +543,7 @@ hrtimer_force_reprogram(struct hrtimer_cpu_base *cpu_base,
int skip_equal)
if (cpu_base->hang_detected)
return;
- if (cpu_base->expires_next.tv64 != KTIME_MAX)
- tick_program_event(cpu_base->expires_next, 1);
+ tick_program_event(cpu_base->expires_next, 1);
}
/*
@@ -1308,8 +1307,7 @@ void hrtimer_interrupt(struct clock_event_device *dev)
raw_spin_unlock(&cpu_base->lock);
/* Reprogramming necessary ? */
- if (expires_next.tv64 == KTIME_MAX ||
- !tick_program_event(expires_next, 0)) {
+ if (!tick_program_event(expires_next, 0)) {
cpu_base->hang_detected = 0;
return;
}
diff --git a/kernel/time/tick-oneshot.c b/kernel/time/tick-oneshot.c
index 67a64b1670bf..f8de75715c2f 100644
--- a/kernel/time/tick-oneshot.c
+++ b/kernel/time/tick-oneshot.c
@@ -28,6 +28,22 @@ int tick_program_event(ktime_t expires, int force)
{
struct clock_event_device *dev =
__this_cpu_read(tick_cpu_device.evtdev);
+ if (unlikely(expires.tv64 == KTIME_MAX)) {
+ /*
+ * We don't need the clock event device any more, stop it.
+ */
+ clockevents_set_state(dev, CLOCK_EVT_STATE_ONESHOT_STOPPED);
+ return 0;
+ }
+
+ if (unlikely(dev->state == CLOCK_EVT_STATE_ONESHOT_STOPPED)) {
+ /*
+ * We need the clock event again, configure it in ONESHOT mode
+ * before using it.
+ */
+ clockevents_set_state(dev, CLOCK_EVT_STATE_ONESHOT);
+ }
+
return clockevents_program_event(dev, expires, force);
}
--
2.3.0.rc0.44.ga94655d
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