On 12/10/2013 01:34 AM, Soren Brinkmann wrote:
From: Thomas Gleixner <tglx@xxxxxxxxxxxxx> 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(). Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Signed-off-by: Soren Brinkmann <soren.brinkmann@xxxxxxxxxx> --- kernel/time/clockevents.c | 29 ++++++++++++++++++++++------- kernel/time/tick-broadcast.c | 25 +++++++++++++++++++------ kernel/time/tick-internal.h | 4 ++++ 3 files changed, 45 insertions(+), 13 deletions(-) diff --git a/kernel/time/clockevents.c b/kernel/time/clockevents.c index 086ad6043bcb..641d91003a45 100644 --- a/kernel/time/clockevents.c +++ b/kernel/time/clockevents.c @@ -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); +} +
./arch/arm/kernel/smp_twd.c should be modified to call __clockevents_update_freq instead of clockevents_update_freq, no ?
/** * 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; } /* diff --git a/kernel/time/tick-broadcast.c b/kernel/time/tick-broadcast.c index 9532690daaa9..63a33b33fc4e 100644 --- a/kernel/time/tick-broadcast.c +++ b/kernel/time/tick-broadcast.c @@ -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); } /* diff --git a/kernel/time/tick-internal.h b/kernel/time/tick-internal.h index 18e71f7fbc2a..22fd431a02eb 100644 --- a/kernel/time/tick-internal.h +++ b/kernel/time/tick-internal.h @@ -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 @@ -154,4 +157,5 @@ 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);
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