clockevents: Provide explicit broadcast oneshot 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 oneshot 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 oneshot 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: Alexandre Courbot <gnurou@gmail.com>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Len Brown <lenb@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephen Warren <swarren@wwwdotorg.org>
Cc: Thierry Reding <thierry.reding@gmail.com>
Cc: Tony Lindgren <tony@atomide.com>
Link: http://lkml.kernel.org/r/13000649.8qZuEDV0OA@vostro.rjw.lan
Signed-off-by: Ingo Molnar <mingo@kernel.org>

3 files changed, 20 insertions, 14 deletions

diff --git a/kernel/time/clockevents.c b/kernel/time/clockevents.c
index dba0b83708b3..7791b1c94ef2 100644
--- a/kernel/time/clockevents.c
+++ b/kernel/time/clockevents.c
@@ -656,8 +656,10 @@ int clockevents_notify(unsigned long reason, void *arg)
 
         switch (reason) {
         case CLOCK_EVT_NOTIFY_BROADCAST_ENTER:
+                tick_broadcast_enter();
+                break;
         case CLOCK_EVT_NOTIFY_BROADCAST_EXIT:
-                ret = tick_broadcast_oneshot_control(reason);
+                tick_broadcast_exit();
                 break;
 
         case CLOCK_EVT_NOTIFY_CPU_DYING:
diff --git a/kernel/time/tick-broadcast.c b/kernel/time/tick-broadcast.c
index 1a0bee04ef8c..55e43f20987a 100644
--- a/kernel/time/tick-broadcast.c
+++ b/kernel/time/tick-broadcast.c
@@ -687,18 +687,23 @@ void hotplug_cpu__broadcast_tick_pull(int deadcpu)
         raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
 }
 
-/*
- * Powerstate information: The system enters/leaves a state, where
- * affected devices might stop
+/**
+ * tick_broadcast_oneshot_control - Enter/exit broadcast oneshot mode
+ * @state:      The target state (enter/exit)
+ *
+ * The system enters/leaves a state, where affected devices might stop
  * Returns 0 on success, -EBUSY if the cpu is used to broadcast wakeups.
+ *
+ * Called with interrupts disabled, so clockevents_lock is not
+ * required here because the local clock event device cannot go away
+ * under us.
  */
-int tick_broadcast_oneshot_control(unsigned long reason)
+int tick_broadcast_oneshot_control(enum tick_broadcast_state state)
 {
         struct clock_event_device *bc, *dev;
         struct tick_device *td;
-        unsigned long flags;
-        ktime_t now;
         int cpu, ret = 0;
+        ktime_t now;
 
         /*
          * Periodic mode does not care about the enter/exit of power
@@ -711,17 +716,17 @@ int tick_broadcast_oneshot_control(unsigned long reason)
          * We are called with preemtion disabled from the depth of the
          * idle code, so we can't be moved away.
          */
-        cpu = smp_processor_id();
-        td = &per_cpu(tick_cpu_device, cpu);
+        td = this_cpu_ptr(&tick_cpu_device);
         dev = td->evtdev;
 
         if (!(dev->features & CLOCK_EVT_FEAT_C3STOP))
                 return 0;
 
+        raw_spin_lock(&tick_broadcast_lock);
         bc = tick_broadcast_device.evtdev;
+        cpu = smp_processor_id();
 
-        raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
-        if (reason == CLOCK_EVT_NOTIFY_BROADCAST_ENTER) {
+        if (state == TICK_BROADCAST_ENTER) {
                 if (!cpumask_test_and_set_cpu(cpu, tick_broadcast_oneshot_mask)) {
                         WARN_ON_ONCE(cpumask_test_cpu(cpu, tick_broadcast_pending_mask));
                         broadcast_shutdown_local(bc, dev);
@@ -813,9 +818,10 @@ int tick_broadcast_oneshot_control(unsigned long reason)
                 }
         }
 out:
-        raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
+        raw_spin_unlock(&tick_broadcast_lock);
         return ret;
 }
+EXPORT_SYMBOL_GPL(tick_broadcast_oneshot_control);
 
 /*
  * Reset the one shot broadcast for a cpu
diff --git a/kernel/time/tick-internal.h b/kernel/time/tick-internal.h
index 62e331d1bc76..0266f9dbd114 100644
--- a/kernel/time/tick-internal.h
+++ b/kernel/time/tick-internal.h
@@ -117,7 +117,6 @@ static inline int tick_check_oneshot_change(int allow_nohz) { return 0; }
 /* Functions related to oneshot broadcasting */
 #if defined(CONFIG_GENERIC_CLOCKEVENTS_BROADCAST) && defined(CONFIG_TICK_ONESHOT)
 extern void tick_broadcast_setup_oneshot(struct clock_event_device *bc);
-extern int tick_broadcast_oneshot_control(unsigned long reason);
 extern void tick_broadcast_switch_to_oneshot(void);
 extern void tick_shutdown_broadcast_oneshot(unsigned int *cpup);
 extern int tick_broadcast_oneshot_active(void);
@@ -126,7 +125,6 @@ bool tick_broadcast_oneshot_available(void);
 extern struct cpumask *tick_get_broadcast_oneshot_mask(void);
 #else /* !(BROADCAST && ONESHOT): */
 static inline void tick_broadcast_setup_oneshot(struct clock_event_device *bc) { BUG(); }
-static inline int tick_broadcast_oneshot_control(unsigned long reason) { return 0; }
 static inline void tick_broadcast_switch_to_oneshot(void) { }
 static inline void tick_shutdown_broadcast_oneshot(unsigned int *cpup) { }
 static inline int tick_broadcast_oneshot_active(void) { return 0; }