[tip:timers/core] clockevents: Cleanup dead cpu explicitely

From: tip-bot for Thomas Gleixner
Date: Fri Apr 03 2015 - 04:27:37 EST

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Commit-ID: a49b116dcb1265f238f3169507424257b0519069
Gitweb: http://git.kernel.org/tip/a49b116dcb1265f238f3169507424257b0519069
Author: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
AuthorDate: Fri, 3 Apr 2015 02:38:05 +0200
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Fri, 3 Apr 2015 08:44:37 +0200

clockevents: Cleanup dead cpu explicitely

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 cleanup function for a dead cpu and invoke it
directly from the cpu down code. Make it conditional on
CPU_HOTPLUG as well.

Temporary change, will be refined in the future.

Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
[ Rebased, added clockevents_notify() removal ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Link: http://lkml.kernel.org/r/1735025.raBZdQHM3m@xxxxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
include/linux/clockchips.h | 6 ------
include/linux/tick.h | 2 ++
kernel/cpu.c | 1 +
kernel/time/clockevents.c | 51 ++++++++++++++++++--------------------------
kernel/time/hrtimer.c | 3 ---
kernel/time/tick-broadcast.c | 39 ++++++++++++++++-----------------
kernel/time/tick-common.c | 6 +++---
kernel/time/tick-internal.h | 10 ++++-----
8 files changed, 52 insertions(+), 66 deletions(-)

diff --git a/include/linux/clockchips.h b/include/linux/clockchips.h
index f4bde22..96c280b 100644
--- a/include/linux/clockchips.h
+++ b/include/linux/clockchips.h
@@ -8,12 +8,6 @@
#ifndef _LINUX_CLOCKCHIPS_H
#define _LINUX_CLOCKCHIPS_H

-/* Clock event notification values */
-enum clock_event_nofitiers {
- CLOCK_EVT_NOTIFY_ADD,
- CLOCK_EVT_NOTIFY_CPU_DEAD,
-};
-
#ifdef CONFIG_GENERIC_CLOCKEVENTS

# include <linux/clocksource.h>
diff --git a/include/linux/tick.h b/include/linux/tick.h
index 2c68fa3..f8492da5 100644
--- a/include/linux/tick.h
+++ b/include/linux/tick.h
@@ -20,6 +20,7 @@ extern void tick_suspend_local(void);
/* Should be core only, but XEN resume magic and ARM BL switcher require it */
extern void tick_resume_local(void);
extern void tick_handover_do_timer(void);
+extern void tick_cleanup_dead_cpu(int cpu);
#else /* CONFIG_GENERIC_CLOCKEVENTS */
static inline void tick_init(void) { }
static inline void tick_freeze(void) { }
@@ -27,6 +28,7 @@ static inline void tick_unfreeze(void) { }
static inline void tick_suspend_local(void) { }
static inline void tick_resume_local(void) { }
static inline void tick_handover_do_timer(void) { }
+static inline void tick_cleanup_dead_cpu(int cpu) { }
#endif /* !CONFIG_GENERIC_CLOCKEVENTS */

#ifdef CONFIG_TICK_ONESHOT
diff --git a/kernel/cpu.c b/kernel/cpu.c
index eba7eaa..82eea9c 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -419,6 +419,7 @@ static int __ref _cpu_down(unsigned int cpu, int tasks_frozen)
__cpu_die(cpu);

/* CPU is completely dead: tell everyone. Too late to complain. */
+ tick_cleanup_dead_cpu(cpu);
cpu_notify_nofail(CPU_DEAD | mod, hcpu);

check_for_tasks(cpu);
diff --git a/kernel/time/clockevents.c b/kernel/time/clockevents.c
index 88fb3b9..25d942d 100644
--- a/kernel/time/clockevents.c
+++ b/kernel/time/clockevents.c
@@ -642,49 +642,40 @@ void clockevents_resume(void)
dev->resume(dev);
}

+#ifdef CONFIG_HOTPLUG_CPU
/**
- * clockevents_notify - notification about relevant events
- * Returns 0 on success, any other value on error
+ * tick_cleanup_dead_cpu - Cleanup the tick and clockevents of a dead cpu
*/
-int clockevents_notify(unsigned long reason, void *arg)
+void tick_cleanup_dead_cpu(int cpu)
{
struct clock_event_device *dev, *tmp;
unsigned long flags;
- int cpu, ret = 0;

raw_spin_lock_irqsave(&clockevents_lock, flags);

- switch (reason) {
- case CLOCK_EVT_NOTIFY_CPU_DEAD:
- tick_shutdown_broadcast_oneshot(arg);
- tick_shutdown_broadcast(arg);
- tick_shutdown(arg);
- /*
- * Unregister the clock event devices which were
- * released from the users in the notify chain.
- */
- list_for_each_entry_safe(dev, tmp, &clockevents_released, list)
+ tick_shutdown_broadcast_oneshot(cpu);
+ tick_shutdown_broadcast(cpu);
+ tick_shutdown(cpu);
+ /*
+ * Unregister the clock event devices which were
+ * released from the users in the notify chain.
+ */
+ list_for_each_entry_safe(dev, tmp, &clockevents_released, list)
+ list_del(&dev->list);
+ /*
+ * Now check whether the CPU has left unused per cpu devices
+ */
+ list_for_each_entry_safe(dev, tmp, &clockevent_devices, list) {
+ if (cpumask_test_cpu(cpu, dev->cpumask) &&
+ cpumask_weight(dev->cpumask) == 1 &&
+ !tick_is_broadcast_device(dev)) {
+ BUG_ON(dev->state != CLOCK_EVT_STATE_DETACHED);
list_del(&dev->list);
- /*
- * Now check whether the CPU has left unused per cpu devices
- */
- cpu = *((int *)arg);
- list_for_each_entry_safe(dev, tmp, &clockevent_devices, list) {
- if (cpumask_test_cpu(cpu, dev->cpumask) &&
- cpumask_weight(dev->cpumask) == 1 &&
- !tick_is_broadcast_device(dev)) {
- BUG_ON(dev->state != CLOCK_EVT_STATE_DETACHED);
- list_del(&dev->list);
- }
}
- break;
- default:
- break;
}
raw_spin_unlock_irqrestore(&clockevents_lock, flags);
- return ret;
}
-EXPORT_SYMBOL_GPL(clockevents_notify);
+#endif

#ifdef CONFIG_SYSFS
struct bus_type clockevents_subsys = {
diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c
index 6a7a64e..76d4bd9 100644
--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -1709,11 +1709,8 @@ static int hrtimer_cpu_notify(struct notifier_block *self,
#ifdef CONFIG_HOTPLUG_CPU
case CPU_DEAD:
case CPU_DEAD_FROZEN:
- {
- clockevents_notify(CLOCK_EVT_NOTIFY_CPU_DEAD, &scpu);
migrate_hrtimers(scpu);
break;
- }
#endif

default:
diff --git a/kernel/time/tick-broadcast.c b/kernel/time/tick-broadcast.c
index 55e43f2..7e8ca4f 100644
--- a/kernel/time/tick-broadcast.c
+++ b/kernel/time/tick-broadcast.c
@@ -410,14 +410,14 @@ void tick_set_periodic_handler(struct clock_event_device *dev, int broadcast)
dev->event_handler = tick_handle_periodic_broadcast;
}

+#ifdef CONFIG_HOTPLUG_CPU
/*
* Remove a CPU from broadcasting
*/
-void tick_shutdown_broadcast(unsigned int *cpup)
+void tick_shutdown_broadcast(unsigned int cpu)
{
struct clock_event_device *bc;
unsigned long flags;
- unsigned int cpu = *cpup;

raw_spin_lock_irqsave(&tick_broadcast_lock, flags);

@@ -432,6 +432,7 @@ void tick_shutdown_broadcast(unsigned int *cpup)

raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
}
+#endif

void tick_suspend_broadcast(void)
{
@@ -672,21 +673,6 @@ static void broadcast_shutdown_local(struct clock_event_device *bc,
clockevents_set_state(dev, CLOCK_EVT_STATE_SHUTDOWN);
}

-void hotplug_cpu__broadcast_tick_pull(int deadcpu)
-{
- struct clock_event_device *bc;
- unsigned long flags;
-
- raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
- bc = tick_broadcast_device.evtdev;
-
- if (bc && broadcast_needs_cpu(bc, deadcpu)) {
- /* This moves the broadcast assignment to this CPU: */
- clockevents_program_event(bc, bc->next_event, 1);
- }
- raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
-}
-
/**
* tick_broadcast_oneshot_control - Enter/exit broadcast oneshot mode
* @state: The target state (enter/exit)
@@ -908,14 +894,28 @@ void tick_broadcast_switch_to_oneshot(void)
raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
}

+#ifdef CONFIG_HOTPLUG_CPU
+void hotplug_cpu__broadcast_tick_pull(int deadcpu)
+{
+ struct clock_event_device *bc;
+ unsigned long flags;
+
+ raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
+ bc = tick_broadcast_device.evtdev;
+
+ if (bc && broadcast_needs_cpu(bc, deadcpu)) {
+ /* This moves the broadcast assignment to this CPU: */
+ clockevents_program_event(bc, bc->next_event, 1);
+ }
+ raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
+}

/*
* Remove a dead CPU from broadcasting
*/
-void tick_shutdown_broadcast_oneshot(unsigned int *cpup)
+void tick_shutdown_broadcast_oneshot(unsigned int cpu)
{
unsigned long flags;
- unsigned int cpu = *cpup;

raw_spin_lock_irqsave(&tick_broadcast_lock, flags);

@@ -929,6 +929,7 @@ void tick_shutdown_broadcast_oneshot(unsigned int *cpup)

raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
}
+#endif

/*
* Check, whether the broadcast device is in one shot mode
diff --git a/kernel/time/tick-common.c b/kernel/time/tick-common.c
index 055c868..fac3e98 100644
--- a/kernel/time/tick-common.c
+++ b/kernel/time/tick-common.c
@@ -348,7 +348,6 @@ void tick_handover_do_timer(void)
TICK_DO_TIMER_NONE;
}
}
-#endif

/*
* Shutdown an event device on a given cpu:
@@ -357,9 +356,9 @@ void tick_handover_do_timer(void)
* access the hardware device itself.
* We just set the mode and remove it from the lists.
*/
-void tick_shutdown(unsigned int *cpup)
+void tick_shutdown(unsigned int cpu)
{
- struct tick_device *td = &per_cpu(tick_cpu_device, *cpup);
+ struct tick_device *td = &per_cpu(tick_cpu_device, cpu);
struct clock_event_device *dev = td->evtdev;

td->mode = TICKDEV_MODE_PERIODIC;
@@ -375,6 +374,7 @@ void tick_shutdown(unsigned int *cpup)
td->evtdev = NULL;
}
}
+#endif

/**
* tick_suspend_local - Suspend the local tick device
diff --git a/kernel/time/tick-internal.h b/kernel/time/tick-internal.h
index aabcb5d..b64fdd8 100644
--- a/kernel/time/tick-internal.h
+++ b/kernel/time/tick-internal.h
@@ -20,7 +20,7 @@ extern int tick_do_timer_cpu __read_mostly;
extern void tick_setup_periodic(struct clock_event_device *dev, int broadcast);
extern void tick_handle_periodic(struct clock_event_device *dev);
extern void tick_check_new_device(struct clock_event_device *dev);
-extern void tick_shutdown(unsigned int *cpup);
+extern void tick_shutdown(unsigned int cpu);
extern void tick_suspend(void);
extern void tick_resume(void);
extern bool tick_check_replacement(struct clock_event_device *curdev,
@@ -52,7 +52,7 @@ 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_shutdown_broadcast(unsigned int *cpup);
+extern void tick_shutdown_broadcast(unsigned int cpu);
extern void tick_suspend_broadcast(void);
extern void tick_resume_broadcast(void);
extern bool tick_resume_check_broadcast(void);
@@ -66,7 +66,7 @@ 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_shutdown_broadcast(unsigned int *cpup) { }
+static inline void tick_shutdown_broadcast(unsigned int cpu) { }
static inline void tick_suspend_broadcast(void) { }
static inline void tick_resume_broadcast(void) { }
static inline bool tick_resume_check_broadcast(void) { return false; }
@@ -117,7 +117,7 @@ static inline int tick_check_oneshot_change(int allow_nohz) { return 0; }
#if defined(CONFIG_GENERIC_CLOCKEVENTS_BROADCAST) && defined(CONFIG_TICK_ONESHOT)
extern void tick_broadcast_setup_oneshot(struct clock_event_device *bc);
extern void tick_broadcast_switch_to_oneshot(void);
-extern void tick_shutdown_broadcast_oneshot(unsigned int *cpup);
+extern void tick_shutdown_broadcast_oneshot(unsigned int cpu);
extern int tick_broadcast_oneshot_active(void);
extern void tick_check_oneshot_broadcast_this_cpu(void);
bool tick_broadcast_oneshot_available(void);
@@ -125,7 +125,7 @@ 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 void tick_broadcast_switch_to_oneshot(void) { }
-static inline void tick_shutdown_broadcast_oneshot(unsigned int *cpup) { }
+static inline void tick_shutdown_broadcast_oneshot(unsigned int cpu) { }
static inline int tick_broadcast_oneshot_active(void) { return 0; }
static inline void tick_check_oneshot_broadcast_this_cpu(void) { }
static inline bool tick_broadcast_oneshot_available(void) { return tick_oneshot_possible(); }
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In reply to: Rafael J. Wysocki: "[v2][PATCH 20/21] clockevents: Cleanup dead cpu explicitely"
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