Commit 627ee794 authored by Thomas Gleixner's avatar Thomas Gleixner
Browse files

clockevents: Serialize calls to clockevents_update_freq() in the core 



We can identify the broadcast device in the core and serialize all
callers including interrupts on a different CPU against the update.
Also, disabling interrupts is moved into the core allowing callers to
leave interrutps enabled when calling clockevents_update_freq().

Signed-off-by: default avatarSoren Brinkmann <soren.brinkmann@xilinx.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: Soeren Brinkmann <soren.brinkmann@xilinx.com>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Michal Simek <michal.simek@xilinx.com>
Link: http://lkml.kernel.org/r/1391466877-28908-2-git-send-email-soren.brinkmann@xilinx.com


Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent e8b17594

kernel/time/clockevents.c

+22 −7
Original line number Diff line number Diff line
@@ -439,6 +439,16 @@ void clockevents_config_and_register(struct clock_event_device *dev, 
}

EXPORT_SYMBOL_GPL(clockevents_config_and_register);



int __clockevents_update_freq(struct clock_event_device *dev, u32 freq)

{

	clockevents_config(dev, freq);



	if (dev->mode != CLOCK_EVT_MODE_ONESHOT)

		return 0;



	return clockevents_program_event(dev, dev->next_event, false);

}



/**

 * clockevents_update_freq - Update frequency and reprogram a clock event device.

 * @dev:	device to modify
@@ -446,17 +456,22 @@ EXPORT_SYMBOL_GPL(clockevents_config_and_register); 
 *

 * Reconfigure and reprogram a clock event device in oneshot

 * mode. Must be called on the cpu for which the device delivers per

 * cpu timer events with interrupts disabled!  Returns 0 on success,

 * -ETIME when the event is in the past.

 * cpu timer events. If called for the broadcast device the core takes

 * care of serialization.

 *

 * Returns 0 on success, -ETIME when the event is in the past.

 */

int clockevents_update_freq(struct clock_event_device *dev, u32 freq)

{

	clockevents_config(dev, freq);



	if (dev->mode != CLOCK_EVT_MODE_ONESHOT)

		return 0;

	unsigned long flags;

	int ret;



	return clockevents_program_event(dev, dev->next_event, false);

	local_irq_save(flags);

	ret = tick_broadcast_update_freq(dev, freq);

	if (ret == -ENODEV)

		ret = __clockevents_update_freq(dev, freq);

	local_irq_restore(flags);

	return ret;

}



/*

kernel/time/tick-broadcast.c

+19 −6
Original line number Diff line number Diff line
@@ -120,6 +120,19 @@ int tick_is_broadcast_device(struct clock_event_device *dev) 
	return (dev && tick_broadcast_device.evtdev == dev);

}



int tick_broadcast_update_freq(struct clock_event_device *dev, u32 freq)

{

	int ret = -ENODEV;



	if (tick_is_broadcast_device(dev)) {

		raw_spin_lock(&tick_broadcast_lock);

		ret = __clockevents_update_freq(dev, freq);

		raw_spin_unlock(&tick_broadcast_lock);

	}

	return ret;

}





static void err_broadcast(const struct cpumask *mask)

{

	pr_crit_once("Failed to broadcast timer tick. Some CPUs may be unresponsive.\n");
@@ -272,12 +285,8 @@ static void tick_do_broadcast(struct cpumask *mask) 
 */

static void tick_do_periodic_broadcast(void)

{

	raw_spin_lock(&tick_broadcast_lock);



	cpumask_and(tmpmask, cpu_online_mask, tick_broadcast_mask);

	tick_do_broadcast(tmpmask);



	raw_spin_unlock(&tick_broadcast_lock);

}



/*
@@ -287,13 +296,15 @@ static void tick_handle_periodic_broadcast(struct clock_event_device *dev) 
{

	ktime_t next;



	raw_spin_lock(&tick_broadcast_lock);



	tick_do_periodic_broadcast();



	/*

	 * The device is in periodic mode. No reprogramming necessary:

	 */

	if (dev->mode == CLOCK_EVT_MODE_PERIODIC)

		return;

		goto unlock;



	/*

	 * Setup the next period for devices, which do not have
@@ -306,9 +317,11 @@ static void tick_handle_periodic_broadcast(struct clock_event_device *dev) 
		next = ktime_add(next, tick_period);



		if (!clockevents_program_event(dev, next, false))

			return;

			goto unlock;

		tick_do_periodic_broadcast();

	}

unlock:

	raw_spin_unlock(&tick_broadcast_lock);

}



/*

kernel/time/tick-internal.h

+4 −0
Original line number Diff line number Diff line
@@ -111,6 +111,7 @@ extern int tick_resume_broadcast(void); 
extern void tick_broadcast_init(void);

extern void

tick_set_periodic_handler(struct clock_event_device *dev, int broadcast);

int tick_broadcast_update_freq(struct clock_event_device *dev, u32 freq);



#else /* !BROADCAST */
@@ -133,6 +134,8 @@ 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; }

static inline void tick_broadcast_init(void) { }

static inline int tick_broadcast_update_freq(struct clock_event_device *dev,

					     u32 freq) { return -ENODEV; }



/*

 * Set the periodic handler in non broadcast mode
@@ -154,5 +157,6 @@ static inline int tick_device_is_functional(struct clock_event_device *dev) 


#endif



int __clockevents_update_freq(struct clock_event_device *dev, u32 freq);

extern void do_timer(unsigned long ticks);

extern void update_wall_time(void);

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