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 <tglx@linutronix.de>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Len Brown <lenb@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Tony Lindgren <tony@atomide.com>
Link: http://lkml.kernel.org/r/8086559.ttsuS0n1Xr@vostro.rjw.lan
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/include/linux/tick.h b/include/linux/tick.h
index f9ff225..4bb2363 100644 (file)
--- 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 7af6148..599ff8d 100644 (file)
--- 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 f5e0fd5..1a0bee0 100644 (file)
--- 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 b6ba0a4..62e331d 100644 (file)
--- 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) { }