From 627ee7947e2e83ba565c31c5c9373d6e364b1ecd Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Mon, 3 Feb 2014 14:34:31 -0800 Subject: [PATCH] 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: Soren Brinkmann Cc: linux-arm-kernel@lists.infradead.org Cc: Soeren Brinkmann Cc: Daniel Lezcano Cc: Michal Simek Link: http://lkml.kernel.org/r/1391466877-28908-2-git-send-email-soren.brinkmann@xilinx.com Signed-off-by: Thomas Gleixner --- kernel/time/clockevents.c | 37 +++++++++++++++++++++++++----------- kernel/time/tick-broadcast.c | 25 ++++++++++++++++++------ kernel/time/tick-internal.h | 4 ++++ 3 files changed, 49 insertions(+), 17 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 @@ -439,17 +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 */ diff --git a/kernel/time/tick-broadcast.c b/kernel/time/tick-broadcast.c index 43780ab5e279..003e6c3663b1 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 8329669b51ec..26f1c0ba9d81 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 @@ -154,5 +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);