Messages in this thread | | | Date | Wed, 11 Dec 2013 15:32:57 +0100 | From | Daniel Lezcano <> | Subject | Re: [PATCH 1/2] time: Serialize calls to 'clockevents_update_freq' in the timing core |
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On 12/10/2013 01:34 AM, Soren Brinkmann wrote: > From: Thomas Gleixner <tglx@linutronix.de> > > 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@linutronix.de> > Signed-off-by: Soren Brinkmann <soren.brinkmann@xilinx.com> > --- > 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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