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Subject[PATCH 01/20] clockevents: Provide explicit broadcast control functions
Date
From: Thomas Gleixner <tglx@linutronix.de>

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 <tglx@linutronix.de>
Cc: Tony Lindgren <tony@atomide.com>
Cc: Len Brown <lenb@kernel.org>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---
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(-)

Index: linux-pm/include/linux/tick.h
===================================================================
--- linux-pm.orig/include/linux/tick.h
+++ linux-pm/include/linux/tick.h
@@ -36,6 +36,31 @@ extern void tick_irq_enter(void);
static inline void tick_irq_enter(void) { }
#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);
Index: linux-pm/kernel/time/clockevents.c
===================================================================
--- linux-pm.orig/kernel/time/clockevents.c
+++ linux-pm/kernel/time/clockevents.c
@@ -656,9 +656,13 @@ int clockevents_notify(unsigned long rea

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:
Index: linux-pm/kernel/time/tick-broadcast.c
===================================================================
--- linux-pm.orig/kernel/time/tick-broadcast.c
+++ linux-pm/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(uns
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
Index: linux-pm/kernel/time/tick-internal.h
===================================================================
--- linux-pm.orig/kernel/time/tick-internal.h
+++ linux-pm/kernel/time/tick-internal.h
@@ -85,7 +85,6 @@ static inline int tick_check_oneshot_cha
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);
@@ -100,7 +99,6 @@ static inline void tick_install_broadcas
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) { }


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