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Subject[PATCH 09/20] clockevents: Provide explicit broadcast oneshot 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 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>
Cc: Tony Lindgren <tony@atomide.com>
Cc: Stephen Warren <swarren@wwwdotorg.org>
Cc: Thierry Reding <thierry.reding@gmail.com>
Cc: Alexandre Courbot <gnurou@gmail.com>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Len Brown <lenb@kernel.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---
include/linux/tick.h | 19 +++++++++++++++++++
kernel/time/clockevents.c | 4 +++-
kernel/time/tick-broadcast.c | 28 +++++++++++++++++-----------
kernel/time/tick-internal.h | 2 --
4 files changed, 39 insertions(+), 14 deletions(-)

Index: linux-pm/include/linux/tick.h
===================================================================
--- linux-pm.orig/include/linux/tick.h
+++ linux-pm/include/linux/tick.h
@@ -42,12 +42,23 @@ enum tick_broadcast_mode {
TICK_BROADCAST_FORCE,
};

+enum tick_broadcast_state {
+ TICK_BROADCAST_EXIT,
+ TICK_BROADCAST_ENTER,
+};
+
#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 */

+#if defined(CONFIG_GENERIC_CLOCKEVENTS_BROADCAST) && defined(CONFIG_TICK_ONESHOT)
+extern int tick_broadcast_oneshot_control(enum tick_broadcast_state state);
+#else
+static inline int tick_broadcast_oneshot_control(enum tick_broadcast_state state) { return 0; }
+#endif
+
static inline void tick_broadcast_enable(void)
{
tick_broadcast_control(TICK_BROADCAST_ON);
@@ -60,6 +71,14 @@ static inline void tick_broadcast_force(
{
tick_broadcast_control(TICK_BROADCAST_FORCE);
}
+static inline int tick_broadcast_enter(void)
+{
+ return tick_broadcast_oneshot_control(TICK_BROADCAST_ENTER);
+}
+static inline void tick_broadcast_exit(void)
+{
+ tick_broadcast_oneshot_control(TICK_BROADCAST_EXIT);
+}

#ifdef CONFIG_NO_HZ_COMMON
extern int tick_nohz_tick_stopped(void);
Index: linux-pm/kernel/time/clockevents.c
===================================================================
--- linux-pm.orig/kernel/time/clockevents.c
+++ linux-pm/kernel/time/clockevents.c
@@ -656,8 +656,10 @@ int clockevents_notify(unsigned long rea

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:
Index: linux-pm/kernel/time/tick-broadcast.c
===================================================================
--- linux-pm.orig/kernel/time/tick-broadcast.c
+++ linux-pm/kernel/time/tick-broadcast.c
@@ -682,18 +682,23 @@ static void broadcast_move_bc(int deadcp
clockevents_program_event(bc, bc->next_event, 1);
}

-/*
- * 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
@@ -706,17 +711,17 @@ int tick_broadcast_oneshot_control(unsig
* 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);
@@ -808,9 +813,10 @@ int tick_broadcast_oneshot_control(unsig
}
}
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
Index: linux-pm/kernel/time/tick-internal.h
===================================================================
--- linux-pm.orig/kernel/time/tick-internal.h
+++ linux-pm/kernel/time/tick-internal.h
@@ -118,7 +118,6 @@ static inline void tick_set_periodic_han
/* 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);
@@ -127,7 +126,6 @@ bool tick_broadcast_oneshot_available(vo
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; }


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