From 592a438ff3fea61d303c5784c209b3f1fd3e16df Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Fri, 3 Apr 2015 02:01:10 +0200 Subject: [PATCH] clockevents: Provide explicit broadcast control functions clockevents_notify() is a leftover from the early design of the clockevents facility. It's really not a notification mechanism, it's a multiplex call. We are way better off to have explicit calls instead of this monstrosity. Split out the broadcast control into a separate function and provide inline helpers. Switch clockevents_notify() over. This will go away once all callers are converted. This also gets rid of the nested locking of clockevents_lock and broadcast_lock. The broadcast control functions do not require clockevents_lock. Only the managing functions (setup/shutdown/suspend/resume of the broadcast device require clockevents_lock. Signed-off-by: Thomas Gleixner Signed-off-by: Rafael J. Wysocki Cc: Daniel Lezcano Cc: Len Brown Cc: Peter Zijlstra Cc: Tony Lindgren Link: http://lkml.kernel.org/r/8086559.ttsuS0n1Xr@vostro.rjw.lan Signed-off-by: Ingo Molnar --- include/linux/tick.h | 25 +++++++++++++++ kernel/time/clockevents.c | 6 +++- kernel/time/tick-broadcast.c | 62 ++++++++++++++++-------------------- kernel/time/tick-internal.h | 2 -- 4 files changed, 57 insertions(+), 38 deletions(-) diff --git a/include/linux/tick.h b/include/linux/tick.h index f9ff225d53c0..4bb236357b03 100644 --- a/include/linux/tick.h +++ b/include/linux/tick.h @@ -42,6 +42,31 @@ extern void hotplug_cpu__broadcast_tick_pull(int dead_cpu); static inline void hotplug_cpu__broadcast_tick_pull(int dead_cpu) { } #endif +enum tick_broadcast_mode { + TICK_BROADCAST_OFF, + TICK_BROADCAST_ON, + TICK_BROADCAST_FORCE, +}; + +#ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST +extern void tick_broadcast_control(enum tick_broadcast_mode mode); +#else +static inline void tick_broadcast_control(enum tick_broadcast_mode mode) { } +#endif /* BROADCAST */ + +static inline void tick_broadcast_enable(void) +{ + tick_broadcast_control(TICK_BROADCAST_ON); +} +static inline void tick_broadcast_disable(void) +{ + tick_broadcast_control(TICK_BROADCAST_OFF); +} +static inline void tick_broadcast_force(void) +{ + tick_broadcast_control(TICK_BROADCAST_FORCE); +} + #ifdef CONFIG_NO_HZ_COMMON extern int tick_nohz_tick_stopped(void); extern void tick_nohz_idle_enter(void); diff --git a/kernel/time/clockevents.c b/kernel/time/clockevents.c index 7af614829da1..599ff8d3fda5 100644 --- a/kernel/time/clockevents.c +++ b/kernel/time/clockevents.c @@ -656,9 +656,13 @@ int clockevents_notify(unsigned long reason, void *arg) switch (reason) { case CLOCK_EVT_NOTIFY_BROADCAST_ON: + tick_broadcast_enable(); + break; case CLOCK_EVT_NOTIFY_BROADCAST_OFF: + tick_broadcast_disable(); + break; case CLOCK_EVT_NOTIFY_BROADCAST_FORCE: - tick_broadcast_on_off(reason, arg); + tick_broadcast_force(); break; case CLOCK_EVT_NOTIFY_BROADCAST_ENTER: diff --git a/kernel/time/tick-broadcast.c b/kernel/time/tick-broadcast.c index f5e0fd5652dc..1a0bee04ef8c 100644 --- a/kernel/time/tick-broadcast.c +++ b/kernel/time/tick-broadcast.c @@ -33,7 +33,7 @@ static cpumask_var_t tick_broadcast_mask; static cpumask_var_t tick_broadcast_on; static cpumask_var_t tmpmask; static DEFINE_RAW_SPINLOCK(tick_broadcast_lock); -static int tick_broadcast_force; +static int tick_broadcast_forced; #ifdef CONFIG_TICK_ONESHOT static void tick_broadcast_clear_oneshot(int cpu); @@ -326,49 +326,54 @@ unlock: raw_spin_unlock(&tick_broadcast_lock); } -/* - * Powerstate information: The system enters/leaves a state, where - * affected devices might stop +/** + * tick_broadcast_control - Enable/disable or force broadcast mode + * @mode: The selected broadcast mode + * + * Called when the system enters a state where affected tick devices + * might stop. Note: TICK_BROADCAST_FORCE cannot be undone. + * + * Called with interrupts disabled, so clockevents_lock is not + * required here because the local clock event device cannot go away + * under us. */ -static void tick_do_broadcast_on_off(unsigned long *reason) +void tick_broadcast_control(enum tick_broadcast_mode mode) { struct clock_event_device *bc, *dev; struct tick_device *td; - unsigned long flags; int cpu, bc_stopped; - raw_spin_lock_irqsave(&tick_broadcast_lock, flags); - - cpu = smp_processor_id(); - td = &per_cpu(tick_cpu_device, cpu); + td = this_cpu_ptr(&tick_cpu_device); dev = td->evtdev; - bc = tick_broadcast_device.evtdev; /* * Is the device not affected by the powerstate ? */ if (!dev || !(dev->features & CLOCK_EVT_FEAT_C3STOP)) - goto out; + return; if (!tick_device_is_functional(dev)) - goto out; + return; + raw_spin_lock(&tick_broadcast_lock); + cpu = smp_processor_id(); + bc = tick_broadcast_device.evtdev; bc_stopped = cpumask_empty(tick_broadcast_mask); - switch (*reason) { - case CLOCK_EVT_NOTIFY_BROADCAST_ON: - case CLOCK_EVT_NOTIFY_BROADCAST_FORCE: + switch (mode) { + case TICK_BROADCAST_FORCE: + tick_broadcast_forced = 1; + case TICK_BROADCAST_ON: cpumask_set_cpu(cpu, tick_broadcast_on); if (!cpumask_test_and_set_cpu(cpu, tick_broadcast_mask)) { if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC) clockevents_shutdown(dev); } - if (*reason == CLOCK_EVT_NOTIFY_BROADCAST_FORCE) - tick_broadcast_force = 1; break; - case CLOCK_EVT_NOTIFY_BROADCAST_OFF: - if (tick_broadcast_force) + + case TICK_BROADCAST_OFF: + if (tick_broadcast_forced) break; cpumask_clear_cpu(cpu, tick_broadcast_on); if (!tick_device_is_functional(dev)) @@ -390,22 +395,9 @@ static void tick_do_broadcast_on_off(unsigned long *reason) else tick_broadcast_setup_oneshot(bc); } -out: - raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags); -} - -/* - * Powerstate information: The system enters/leaves a state, where - * affected devices might stop. - */ -void tick_broadcast_on_off(unsigned long reason, int *oncpu) -{ - if (!cpumask_test_cpu(*oncpu, cpu_online_mask)) - printk(KERN_ERR "tick-broadcast: ignoring broadcast for " - "offline CPU #%d\n", *oncpu); - else - tick_do_broadcast_on_off(&reason); + raw_spin_unlock(&tick_broadcast_lock); } +EXPORT_SYMBOL_GPL(tick_broadcast_control); /* * Set the periodic handler depending on broadcast on/off diff --git a/kernel/time/tick-internal.h b/kernel/time/tick-internal.h index b6ba0a44e740..62e331d1bc76 100644 --- a/kernel/time/tick-internal.h +++ b/kernel/time/tick-internal.h @@ -53,7 +53,6 @@ extern ssize_t sysfs_get_uname(const char *buf, char *dst, size_t cnt); extern int tick_device_uses_broadcast(struct clock_event_device *dev, int cpu); extern void tick_install_broadcast_device(struct clock_event_device *dev); extern int tick_is_broadcast_device(struct clock_event_device *dev); -extern void tick_broadcast_on_off(unsigned long reason, int *oncpu); extern void tick_shutdown_broadcast(unsigned int *cpup); extern void tick_suspend_broadcast(void); extern void tick_resume_broadcast(void); @@ -68,7 +67,6 @@ static inline void tick_install_broadcast_device(struct clock_event_device *dev) static inline int tick_is_broadcast_device(struct clock_event_device *dev) { return 0; } static inline int tick_device_uses_broadcast(struct clock_event_device *dev, int cpu) { return 0; } static inline void tick_do_periodic_broadcast(struct clock_event_device *d) { } -static inline void tick_broadcast_on_off(unsigned long reason, int *oncpu) { } static inline void tick_shutdown_broadcast(unsigned int *cpup) { } static inline void tick_suspend_broadcast(void) { } static inline void tick_resume_broadcast(void) { } -- 2.20.1