Commit 2344abbc authored by Thomas Gleixner's avatar Thomas Gleixner
Browse files

clockevents: make device shutdown robust 



The device shut down does not cleanup the next_event variable of the
clock event device. So when the device is reactivated the possible
stale next_event value can prevent the device to be reprogrammed as it
claims to wait on a event already.

This is the root cause of the resurfacing suspend/resume problem,
where systems need key press to come back to life.

Fix this by setting next_event to KTIME_MAX when the device is shut
down. Use a separate function for shutdown which takes care of that
and only keep the direct set mode call in the broadcast code, where we
can not touch the next_event value.

Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent f1926ce6

kernel/time/clockevents.c

+11 −1
Original line number Diff line number Diff line
@@ -71,6 +71,16 @@ void clockevents_set_mode(struct clock_event_device *dev, 
	}

}



/**

 * clockevents_shutdown - shutdown the device and clear next_event

 * @dev:	device to shutdown

 */

void clockevents_shutdown(struct clock_event_device *dev)

{

	clockevents_set_mode(dev, CLOCK_EVT_MODE_SHUTDOWN);

	dev->next_event.tv64 = KTIME_MAX;

}



/**

 * clockevents_program_event - Reprogram the clock event device.

 * @expires:	absolute expiry time (monotonic clock)
@@ -206,7 +216,7 @@ void clockevents_exchange_device(struct clock_event_device *old, 


	if (new) {

		BUG_ON(new->mode != CLOCK_EVT_MODE_UNUSED);

		clockevents_set_mode(new, CLOCK_EVT_MODE_SHUTDOWN);

		clockevents_shutdown(new);

	}

	local_irq_restore(flags);

}

kernel/time/tick-broadcast.c

+4 −5
Original line number Diff line number Diff line
@@ -236,8 +236,7 @@ static void tick_do_broadcast_on_off(void *why) 
		if (!cpu_isset(cpu, tick_broadcast_mask)) {

			cpu_set(cpu, tick_broadcast_mask);

			if (td->mode == TICKDEV_MODE_PERIODIC)

				clockevents_set_mode(dev,

						     CLOCK_EVT_MODE_SHUTDOWN);

				clockevents_shutdown(dev);

		}

		if (*reason == CLOCK_EVT_NOTIFY_BROADCAST_FORCE)

			tick_broadcast_force = 1;
@@ -254,7 +253,7 @@ static void tick_do_broadcast_on_off(void *why) 


	if (cpus_empty(tick_broadcast_mask)) {

		if (!bc_stopped)

			clockevents_set_mode(bc, CLOCK_EVT_MODE_SHUTDOWN);

			clockevents_shutdown(bc);

	} else if (bc_stopped) {

		if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC)

			tick_broadcast_start_periodic(bc);
@@ -306,7 +305,7 @@ void tick_shutdown_broadcast(unsigned int *cpup) 


	if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC) {

		if (bc && cpus_empty(tick_broadcast_mask))

			clockevents_set_mode(bc, CLOCK_EVT_MODE_SHUTDOWN);

			clockevents_shutdown(bc);

	}



	spin_unlock_irqrestore(&tick_broadcast_lock, flags);
@@ -321,7 +320,7 @@ void tick_suspend_broadcast(void) 


	bc = tick_broadcast_device.evtdev;

	if (bc)

		clockevents_set_mode(bc, CLOCK_EVT_MODE_SHUTDOWN);

		clockevents_shutdown(bc);



	spin_unlock_irqrestore(&tick_broadcast_lock, flags);

}

kernel/time/tick-common.c

+2 −2
Original line number Diff line number Diff line
@@ -249,7 +249,7 @@ static int tick_check_new_device(struct clock_event_device *newdev) 
	 * not give it back to the clockevents layer !

	 */

	if (tick_is_broadcast_device(curdev)) {

		clockevents_set_mode(curdev, CLOCK_EVT_MODE_SHUTDOWN);

		clockevents_shutdown(curdev);

		curdev = NULL;

	}

	clockevents_exchange_device(curdev, newdev);
@@ -311,7 +311,7 @@ static void tick_suspend(void) 
	unsigned long flags;



	spin_lock_irqsave(&tick_device_lock, flags);

	clockevents_set_mode(td->evtdev, CLOCK_EVT_MODE_SHUTDOWN);

	clockevents_shutdown(td->evtdev);

	spin_unlock_irqrestore(&tick_device_lock, flags);

}

kernel/time/tick-internal.h

+2 −0
Original line number Diff line number Diff line
@@ -10,6 +10,8 @@ extern int tick_do_timer_cpu __read_mostly; 
extern void tick_setup_periodic(struct clock_event_device *dev, int broadcast);

extern void tick_handle_periodic(struct clock_event_device *dev);



extern void clockevents_shutdown(struct clock_event_device *dev);



/*

 * NO_HZ / high resolution timer shared code

 */

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