Re: [5/6] 2.6.21-rc2: known regressions

Ingo Molnar
2007-03-06T07:29:08Z

* Linus Torvalds <torvalds@linux-foundation.org> wrote:

> > Compiling right now - delayed because I just had to pick up one of
> > the kids from gymnastics.
>
> Ok, it does indeed solve the problem for me.
>
> Mind sending a signed-off thing with explanations etc?

here's Thomas' patch with explanations:

------------------------->
From: Thomas Gleixner <tglx@linutronix.de>

The programming of periodic tick devices needs to be saved/restored
across suspend/resume - otherwise we might end up with a system coming
up that relies on getting a PIT (or HPET) interrupt, while those devices
default to 'no interrupts' after powerup. (To confuse things it worked
to a certain degree on some systems because the lapic gets initialized
as a side-effect of SMP bootup.)

This suspend / resume thing was dropped unintentionally during the
last-minute -mm code reshuffling.

Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/kernel/time/tick-broadcast.c b/kernel/time/tick-broadcast.c
index 12b3efe..5567745 100644
--- a/kernel/time/tick-broadcast.c
+++ b/kernel/time/tick-broadcast.c
@@ -284,6 +284,42 @@ void tick_shutdown_broadcast(unsigned int *cpup)
spin_unlock_irqrestore(&tick_broadcast_lock, flags);
}

+void tick_suspend_broadcast(void)
+{
+ struct clock_event_device *bc;
+ unsigned long flags;
+
+ spin_lock_irqsave(&tick_broadcast_lock, flags);
+
+ bc = tick_broadcast_device.evtdev;
+ if (bc && tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC)
+ clockevents_set_mode(bc, CLOCK_EVT_MODE_SHUTDOWN);
+
+ spin_unlock_irqrestore(&tick_broadcast_lock, flags);
+}
+
+int tick_resume_broadcast(void)
+{
+ struct clock_event_device *bc;
+ unsigned long flags;
+ int broadcast = 0;
+
+ spin_lock_irqsave(&tick_broadcast_lock, flags);
+
+ bc = tick_broadcast_device.evtdev;
+ if (bc) {
+ if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC &&
+ !cpus_empty(tick_broadcast_mask))
+ tick_broadcast_start_periodic(bc);
+
+ broadcast = cpu_isset(smp_processor_id(), tick_broadcast_mask);
+ }
+ spin_unlock_irqrestore(&tick_broadcast_lock, flags);
+
+ return broadcast;
+}
+
+
#ifdef CONFIG_TICK_ONESHOT

static cpumask_t tick_broadcast_oneshot_mask;
diff --git a/kernel/time/tick-common.c b/kernel/time/tick-common.c
index 0986a2b..43ba1bd 100644
--- a/kernel/time/tick-common.c
+++ b/kernel/time/tick-common.c
@@ -298,6 +298,28 @@ static void tick_shutdown(unsigned int *cpup)
spin_unlock_irqrestore(&tick_device_lock, flags);
}

+static void tick_suspend_periodic(void)
+{
+ struct tick_device *td = &__get_cpu_var(tick_cpu_device);
+ unsigned long flags;
+
+ spin_lock_irqsave(&tick_device_lock, flags);
+ if (td->mode == TICKDEV_MODE_PERIODIC)
+ clockevents_set_mode(td->evtdev, CLOCK_EVT_MODE_SHUTDOWN);
+ spin_unlock_irqrestore(&tick_device_lock, flags);
+}
+
+static void tick_resume_periodic(void)
+{
+ struct tick_device *td = &__get_cpu_var(tick_cpu_device);
+ unsigned long flags;
+
+ spin_lock_irqsave(&tick_device_lock, flags);
+ if (td->mode == TICKDEV_MODE_PERIODIC)
+ tick_setup_periodic(td->evtdev, 0);
+ spin_unlock_irqrestore(&tick_device_lock, flags);
+}
+
/*
* Notification about clock event devices
*/
@@ -325,6 +347,16 @@ static int tick_notify(struct notifier_block *nb, unsigned long reason,
tick_shutdown(dev);
break;

+ case CLOCK_EVT_NOTIFY_SUSPEND:
+ tick_suspend_periodic();
+ tick_suspend_broadcast();
+ break;
+
+ case CLOCK_EVT_NOTIFY_RESUME:
+ if (!tick_resume_broadcast())
+ tick_resume_periodic();
+ break;
+
default:
break;
}
diff --git a/kernel/time/tick-internal.h b/kernel/time/tick-internal.h
index 54861a0..75890ef 100644
--- a/kernel/time/tick-internal.h
+++ b/kernel/time/tick-internal.h
@@ -67,6 +67,8 @@ extern int tick_check_broadcast_device(struct clock_event_device *dev);
extern int tick_is_broadcast_device(struct clock_event_device *dev);
extern void tick_broadcast_on_off(unsigned long reason, int *oncpu);
extern void tick_shutdown_broadcast(unsigned int *cpup);
+extern void tick_suspend_broadcast(void);
+extern int tick_resume_broadcast(void);

extern void
tick_set_periodic_handler(struct clock_event_device *dev, int broadcast);
@@ -90,6 +92,8 @@ static inline int tick_device_uses_broadcast(struct clock_event_device *dev,
static inline void tick_do_periodic_broadcast(struct clock_event_device *d) { }
static inline void tick_broadcast_on_off(unsigned long reason, int *oncpu) { }
static inline void tick_shutdown_broadcast(unsigned int *cpup) { }
+static inline void tick_suspend_broadcast(void) { }
+static inline int tick_resume_broadcast(void) { return 0; }

/*
* Set the periodic handler in non broadcast mode
diff --git a/kernel/timer.c b/kernel/timer.c
index 6663a87..718437f 100644
--- a/kernel/timer.c
+++ b/kernel/timer.c
@@ -997,6 +997,9 @@ static int timekeeping_resume(struct sys_device *dev)
write_sequnlock_irqrestore(&xtime_lock, flags);

touch_softlockup_watchdog();
+
+ clockevents_notify(CLOCK_EVT_NOTIFY_RESUME, NULL);
+
/* Resume hrtimers */
clock_was_set();

@@ -1011,6 +1014,9 @@ static int timekeeping_suspend(struct sys_device *dev, pm_message_t state)
timekeeping_suspended = 1;
timekeeping_suspend_time = read_persistent_clock();
write_sequnlock_irqrestore(&xtime_lock, flags);
+
+ clockevents_notify(CLOCK_EVT_NOTIFY_SUSPEND, NULL);
+
return 0;
}