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clockevents: Serialize calls to clockevents_update_freq() in the core

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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: Soren 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: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Thomas Gleixner 2014-02-03 14:34:31 -08:00
parent e8b175946c
commit 627ee7947e
3 changed files with 49 additions and 17 deletions
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37
kernel/time/clockevents.c
View file

@ -439,17 +439,7 @@ void clockevents_config_and_register(struct clock_event_device *dev,
}
EXPORT_SYMBOL_GPL(clockevents_config_and_register);
/**
* clockevents_update_freq - Update frequency and reprogram a clock event device.
* @dev: device to modify
* @freq: new device frequency
*
* 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.
*/
int clockevents_update_freq(struct clock_event_device *dev, u32 freq)
int __clockevents_update_freq(struct clock_event_device *dev, u32 freq)
{
clockevents_config(dev, freq);
@ -459,6 +449,31 @@ int clockevents_update_freq(struct clock_event_device *dev, u32 freq)
return clockevents_program_event(dev, dev->next_event, false);
}
/**
* clockevents_update_freq - Update frequency and reprogram a clock event device.
* @dev: device to modify
* @freq: new device frequency
*
* 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. 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)
{
unsigned long flags;
int ret;
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;
}
/*
* Noop handler when we shut down an event device
*/

25
kernel/time/tick-broadcast.c
View file

@ -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);
}
/*

4
kernel/time/tick-internal.h
View file

@ -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);