| Message ID | 1386635686-15686-2-git-send-email-soren.brinkmann@xilinx.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
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); >
Hi Daniel, On Wed, Dec 11, 2013 at 03:32:57PM +0100, Daniel Lezcano wrote: > 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 ? IIUC, the __-version is only for timer core internal usage and not an exported interface. Doesn't the non-__ version work for the twd? I don't see issues on my Zynq platform with these patches. Another side note regarding the twd: Shouldn't we set the CLOCK_EVT_FEAT_PERCPU flag we introduced recently for that timer? Sören
On 12/11/2013 09:09 PM, Sören Brinkmann wrote: > Hi Daniel, > > On Wed, Dec 11, 2013 at 03:32:57PM +0100, Daniel Lezcano wrote: >> 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 ? > > IIUC, the __-version is only for timer core internal usage and not an > exported interface. Doesn't the non-__ version work for the twd? > I don't see issues on my Zynq platform with these patches. I don't think there is an issue but if we can rid of the extra code added in clockevents_update_freq with this patch for twd, it would make sense. The __-version means the function is lockless and there is a function without '__' in the name with the lock. > Another side note regarding the twd: Shouldn't we set the > CLOCK_EVT_FEAT_PERCPU flag we introduced recently for that timer? Yes. There will be some fun with the patchset http://lwn.net/Articles/566270/ where the local timer could be used as a broadcast timer.
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); +} + /** * 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);