diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c
index 3d0c6fb74ae4..3f1f8daf703c 100644
--- a/arch/arm/kernel/process.c
+++ b/arch/arm/kernel/process.c
@@ -183,7 +183,7 @@ void cpu_idle(void)
/* endless idle loop with no priority at all */
while (1) {
- tick_nohz_stop_sched_tick(1);
+ tick_nohz_idle_enter();
leds_event(led_idle_start);
while (!need_resched()) {
#ifdef CONFIG_HOTPLUG_CPU
@@ -213,7 +213,7 @@ void cpu_idle(void)
}
}
leds_event(led_idle_end);
- tick_nohz_restart_sched_tick();
+ tick_nohz_idle_exit();
preempt_enable_no_resched();
schedule();
preempt_disable();
diff --git a/arch/avr32/kernel/process.c b/arch/avr32/kernel/process.c
index ef5a2a08fcca..6ee7952248db 100644
--- a/arch/avr32/kernel/process.c
+++ b/arch/avr32/kernel/process.c
@@ -34,10 +34,10 @@ void cpu_idle(void)
{
/* endless idle loop with no priority at all */
while (1) {
- tick_nohz_stop_sched_tick(1);
+ tick_nohz_idle_enter();
while (!need_resched())
cpu_idle_sleep();
- tick_nohz_restart_sched_tick();
+ tick_nohz_idle_exit();
preempt_enable_no_resched();
schedule();
preempt_disable();
diff --git a/arch/blackfin/kernel/process.c b/arch/blackfin/kernel/process.c
index 6a80a9e9fc4a..7b141b5c9e8d 100644
--- a/arch/blackfin/kernel/process.c
+++ b/arch/blackfin/kernel/process.c
@@ -88,10 +88,10 @@ void cpu_idle(void)
#endif
if (!idle)
idle = default_idle;
- tick_nohz_stop_sched_tick(1);
+ tick_nohz_idle_enter();
while (!need_resched())
idle();
- tick_nohz_restart_sched_tick();
+ tick_nohz_idle_exit();
preempt_enable_no_resched();
schedule();
preempt_disable();
diff --git a/arch/microblaze/kernel/process.c b/arch/microblaze/kernel/process.c
index 95cc295976a7..5407f09b4be4 100644
--- a/arch/microblaze/kernel/process.c
+++ b/arch/microblaze/kernel/process.c
@@ -103,10 +103,10 @@ void cpu_idle(void)
if (!idle)
idle = default_idle;
- tick_nohz_stop_sched_tick(1);
+ tick_nohz_idle_enter();
while (!need_resched())
idle();
- tick_nohz_restart_sched_tick();
+ tick_nohz_idle_exit();
preempt_enable_no_resched();
schedule();
diff --git a/arch/mips/kernel/process.c b/arch/mips/kernel/process.c
index c47f96e453c0..c11e5ca2a434 100644
--- a/arch/mips/kernel/process.c
+++ b/arch/mips/kernel/process.c
@@ -56,7 +56,7 @@ void __noreturn cpu_idle(void)
/* endless idle loop with no priority at all */
while (1) {
- tick_nohz_stop_sched_tick(1);
+ tick_nohz_idle_enter();
while (!need_resched() && cpu_online(cpu)) {
#ifdef CONFIG_MIPS_MT_SMTC
extern void smtc_idle_loop_hook(void);
@@ -77,7 +77,7 @@ void __noreturn cpu_idle(void)
system_state == SYSTEM_BOOTING))
play_dead();
#endif
- tick_nohz_restart_sched_tick();
+ tick_nohz_idle_exit();
preempt_enable_no_resched();
schedule();
preempt_disable();
diff --git a/arch/openrisc/kernel/idle.c b/arch/openrisc/kernel/idle.c
index d5bc5f813e89..fb6a9bf40006 100644
--- a/arch/openrisc/kernel/idle.c
+++ b/arch/openrisc/kernel/idle.c
@@ -51,7 +51,7 @@ void cpu_idle(void)
/* endless idle loop with no priority at all */
while (1) {
- tick_nohz_stop_sched_tick(1);
+ tick_nohz_idle_enter();
while (!need_resched()) {
check_pgt_cache();
@@ -69,7 +69,7 @@ void cpu_idle(void)
set_thread_flag(TIF_POLLING_NRFLAG);
}
- tick_nohz_restart_sched_tick();
+ tick_nohz_idle_exit();
preempt_enable_no_resched();
schedule();
preempt_disable();
diff --git a/arch/powerpc/kernel/idle.c b/arch/powerpc/kernel/idle.c
index 39a2baa6ad58..878572f70ac5 100644
--- a/arch/powerpc/kernel/idle.c
+++ b/arch/powerpc/kernel/idle.c
@@ -56,7 +56,7 @@ void cpu_idle(void)
set_thread_flag(TIF_POLLING_NRFLAG);
while (1) {
- tick_nohz_stop_sched_tick(1);
+ tick_nohz_idle_enter();
while (!need_resched() && !cpu_should_die()) {
ppc64_runlatch_off();
@@ -93,7 +93,7 @@ void cpu_idle(void)
HMT_medium();
ppc64_runlatch_on();
- tick_nohz_restart_sched_tick();
+ tick_nohz_idle_exit();
preempt_enable_no_resched();
if (cpu_should_die())
cpu_die();
diff --git a/arch/powerpc/platforms/iseries/setup.c b/arch/powerpc/platforms/iseries/setup.c
index ea0acbd8966d..e83dfaf89f69 100644
--- a/arch/powerpc/platforms/iseries/setup.c
+++ b/arch/powerpc/platforms/iseries/setup.c
@@ -563,7 +563,7 @@ static void yield_shared_processor(void)
static void iseries_shared_idle(void)
{
while (1) {
- tick_nohz_stop_sched_tick(1);
+ tick_nohz_idle_enter();
while (!need_resched() && !hvlpevent_is_pending()) {
local_irq_disable();
ppc64_runlatch_off();
@@ -577,7 +577,7 @@ static void iseries_shared_idle(void)
}
ppc64_runlatch_on();
- tick_nohz_restart_sched_tick();
+ tick_nohz_idle_exit();
if (hvlpevent_is_pending())
process_iSeries_events();
@@ -593,7 +593,7 @@ static void iseries_dedicated_idle(void)
set_thread_flag(TIF_POLLING_NRFLAG);
while (1) {
- tick_nohz_stop_sched_tick(1);
+ tick_nohz_idle_enter();
if (!need_resched()) {
while (!need_resched()) {
ppc64_runlatch_off();
@@ -610,7 +610,7 @@ static void iseries_dedicated_idle(void)
}
ppc64_runlatch_on();
- tick_nohz_restart_sched_tick();
+ tick_nohz_idle_exit();
preempt_enable_no_resched();
schedule();
preempt_disable();
diff --git a/arch/s390/kernel/process.c b/arch/s390/kernel/process.c
index 9451b210a1b4..6224f9dbbc1f 100644
--- a/arch/s390/kernel/process.c
+++ b/arch/s390/kernel/process.c
@@ -91,10 +91,10 @@ static void default_idle(void)
void cpu_idle(void)
{
for (;;) {
- tick_nohz_stop_sched_tick(1);
+ tick_nohz_idle_enter();
while (!need_resched())
default_idle();
- tick_nohz_restart_sched_tick();
+ tick_nohz_idle_exit();
preempt_enable_no_resched();
schedule();
preempt_disable();
diff --git a/arch/sh/kernel/idle.c b/arch/sh/kernel/idle.c
index db4ecd731a00..6015743020a0 100644
--- a/arch/sh/kernel/idle.c
+++ b/arch/sh/kernel/idle.c
@@ -89,7 +89,7 @@ void cpu_idle(void)
/* endless idle loop with no priority at all */
while (1) {
- tick_nohz_stop_sched_tick(1);
+ tick_nohz_idle_enter();
while (!need_resched()) {
check_pgt_cache();
@@ -111,7 +111,7 @@ void cpu_idle(void)
start_critical_timings();
}
- tick_nohz_restart_sched_tick();
+ tick_nohz_idle_exit();
preempt_enable_no_resched();
schedule();
preempt_disable();
diff --git a/arch/sparc/kernel/process_64.c b/arch/sparc/kernel/process_64.c
index 3739a06a76cb..9c2795ba2cfe 100644
--- a/arch/sparc/kernel/process_64.c
+++ b/arch/sparc/kernel/process_64.c
@@ -95,12 +95,12 @@ void cpu_idle(void)
set_thread_flag(TIF_POLLING_NRFLAG);
while(1) {
- tick_nohz_stop_sched_tick(1);
+ tick_nohz_idle_enter();
while (!need_resched() && !cpu_is_offline(cpu))
sparc64_yield(cpu);
- tick_nohz_restart_sched_tick();
+ tick_nohz_idle_exit();
preempt_enable_no_resched();
diff --git a/arch/tile/kernel/process.c b/arch/tile/kernel/process.c
index 9c45d8bbdf57..920e674aedb9 100644
--- a/arch/tile/kernel/process.c
+++ b/arch/tile/kernel/process.c
@@ -85,7 +85,7 @@ void cpu_idle(void)
/* endless idle loop with no priority at all */
while (1) {
- tick_nohz_stop_sched_tick(1);
+ tick_nohz_idle_enter();
while (!need_resched()) {
if (cpu_is_offline(cpu))
BUG(); /* no HOTPLUG_CPU */
@@ -105,7 +105,7 @@ void cpu_idle(void)
local_irq_enable();
current_thread_info()->status |= TS_POLLING;
}
- tick_nohz_restart_sched_tick();
+ tick_nohz_idle_exit();
preempt_enable_no_resched();
schedule();
preempt_disable();
diff --git a/arch/um/kernel/process.c b/arch/um/kernel/process.c
index c5338351aecd..cfb657e92849 100644
--- a/arch/um/kernel/process.c
+++ b/arch/um/kernel/process.c
@@ -246,10 +246,10 @@ void default_idle(void)
if (need_resched())
schedule();
- tick_nohz_stop_sched_tick(1);
+ tick_nohz_idle_enter();
nsecs = disable_timer();
idle_sleep(nsecs);
- tick_nohz_restart_sched_tick();
+ tick_nohz_idle_exit();
}
}
diff --git a/arch/unicore32/kernel/process.c b/arch/unicore32/kernel/process.c
index ba401df971ed..9999b9a84d46 100644
--- a/arch/unicore32/kernel/process.c
+++ b/arch/unicore32/kernel/process.c
@@ -55,7 +55,7 @@ void cpu_idle(void)
{
/* endless idle loop with no priority at all */
while (1) {
- tick_nohz_stop_sched_tick(1);
+ tick_nohz_idle_enter();
while (!need_resched()) {
local_irq_disable();
stop_critical_timings();
@@ -63,7 +63,7 @@ void cpu_idle(void)
local_irq_enable();
start_critical_timings();
}
- tick_nohz_restart_sched_tick();
+ tick_nohz_idle_exit();
preempt_enable_no_resched();
schedule();
preempt_disable();
diff --git a/arch/x86/kernel/process_32.c b/arch/x86/kernel/process_32.c
index 795b79f984c2..6d9d4d52cac5 100644
--- a/arch/x86/kernel/process_32.c
+++ b/arch/x86/kernel/process_32.c
@@ -99,7 +99,7 @@ void cpu_idle(void)
/* endless idle loop with no priority at all */
while (1) {
- tick_nohz_stop_sched_tick(1);
+ tick_nohz_idle_enter();
while (!need_resched()) {
check_pgt_cache();
@@ -116,7 +116,7 @@ void cpu_idle(void)
pm_idle();
start_critical_timings();
}
- tick_nohz_restart_sched_tick();
+ tick_nohz_idle_exit();
preempt_enable_no_resched();
schedule();
preempt_disable();
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index 3bd7e6eebf31..b069e9d7875f 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -122,7 +122,7 @@ void cpu_idle(void)
/* endless idle loop with no priority at all */
while (1) {
- tick_nohz_stop_sched_tick(1);
+ tick_nohz_idle_enter();
while (!need_resched()) {
rmb();
@@ -149,7 +149,7 @@ void cpu_idle(void)
__exit_idle();
}
- tick_nohz_restart_sched_tick();
+ tick_nohz_idle_exit();
preempt_enable_no_resched();
schedule();
preempt_disable();
diff --git a/include/linux/tick.h b/include/linux/tick.h
index ca40838fdfb7..0df1d50a408a 100644
--- a/include/linux/tick.h
+++ b/include/linux/tick.h
@@ -121,21 +121,22 @@ static inline int tick_oneshot_mode_active(void) { return 0; }
#endif /* !CONFIG_GENERIC_CLOCKEVENTS */
# ifdef CONFIG_NO_HZ
-extern void tick_nohz_stop_sched_tick(int inidle);
-extern void tick_nohz_restart_sched_tick(void);
+extern void tick_nohz_idle_enter(void);
+extern void tick_nohz_idle_exit(void);
+extern void tick_nohz_irq_exit(void);
extern ktime_t tick_nohz_get_sleep_length(void);
extern u64 get_cpu_idle_time_us(int cpu, u64 *last_update_time);
extern u64 get_cpu_iowait_time_us(int cpu, u64 *last_update_time);
# else
-static inline void tick_nohz_stop_sched_tick(int inidle)
+static inline void tick_nohz_idle_enter(void)
{
- if (inidle)
- rcu_idle_enter();
+ rcu_idle_enter();
}
-static inline void tick_nohz_restart_sched_tick(void)
+static inline void tick_nohz_idle_exit(void)
{
rcu_idle_exit();
}
+
static inline ktime_t tick_nohz_get_sleep_length(void)
{
ktime_t len = { .tv64 = NSEC_PER_SEC/HZ };
diff --git a/kernel/softirq.c b/kernel/softirq.c
index 2c71d91efff0..f9f2aa81ce53 100644
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -351,7 +351,7 @@ void irq_exit(void)
#ifdef CONFIG_NO_HZ
/* Make sure that timer wheel updates are propagated */
if (idle_cpu(smp_processor_id()) && !in_interrupt() && !need_resched())
- tick_nohz_stop_sched_tick(0);
+ tick_nohz_irq_exit();
#endif
preempt_enable_no_resched();
}
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index 5d9d23665f12..266c242dc354 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -275,42 +275,17 @@ u64 get_cpu_iowait_time_us(int cpu, u64 *last_update_time)
}
EXPORT_SYMBOL_GPL(get_cpu_iowait_time_us);
-/**
- * tick_nohz_stop_sched_tick - stop the idle tick from the idle task
- *
- * When the next event is more than a tick into the future, stop the idle tick
- * Called either from the idle loop or from irq_exit() when an idle period was
- * just interrupted by an interrupt which did not cause a reschedule.
- */
-void tick_nohz_stop_sched_tick(int inidle)
+static void tick_nohz_stop_sched_tick(struct tick_sched *ts)
{
- unsigned long seq, last_jiffies, next_jiffies, delta_jiffies, flags;
- struct tick_sched *ts;
+ unsigned long seq, last_jiffies, next_jiffies, delta_jiffies;
ktime_t last_update, expires, now;
struct clock_event_device *dev = __get_cpu_var(tick_cpu_device).evtdev;
u64 time_delta;
int cpu;
- local_irq_save(flags);
-
cpu = smp_processor_id();
ts = &per_cpu(tick_cpu_sched, cpu);
- /*
- * Call to tick_nohz_start_idle stops the last_update_time from being
- * updated. Thus, it must not be called in the event we are called from
- * irq_exit() with the prior state different than idle.
- */
- if (!inidle && !ts->inidle)
- goto end;
-
- /*
- * Set ts->inidle unconditionally. Even if the system did not
- * switch to NOHZ mode the cpu frequency governers rely on the
- * update of the idle time accounting in tick_nohz_start_idle().
- */
- ts->inidle = 1;
-
now = tick_nohz_start_idle(cpu, ts);
/*
@@ -326,10 +301,10 @@ void tick_nohz_stop_sched_tick(int inidle)
}
if (unlikely(ts->nohz_mode == NOHZ_MODE_INACTIVE))
- goto end;
+ return;
if (need_resched())
- goto end;
+ return;
if (unlikely(local_softirq_pending() && cpu_online(cpu))) {
static int ratelimit;
@@ -339,7 +314,7 @@ void tick_nohz_stop_sched_tick(int inidle)
(unsigned int) local_softirq_pending());
ratelimit++;
}
- goto end;
+ return;
}
ts->idle_calls++;
@@ -471,10 +446,54 @@ out:
ts->next_jiffies = next_jiffies;
ts->last_jiffies = last_jiffies;
ts->sleep_length = ktime_sub(dev->next_event, now);
-end:
- if (inidle)
- rcu_idle_enter();
- local_irq_restore(flags);
+}
+
+/**
+ * tick_nohz_idle_enter - stop the idle tick from the idle task
+ *
+ * When the next event is more than a tick into the future, stop the idle tick
+ * Called when we start the idle loop.
+ * This also enters into RCU extended quiescent state so that this CPU doesn't
+ * need anymore to be part of any global grace period completion. This way
+ * the tick can be stopped safely as we don't need to report quiescent states.
+ */
+void tick_nohz_idle_enter(void)
+{
+ struct tick_sched *ts;
+
+ WARN_ON_ONCE(irqs_disabled());
+
+ local_irq_disable();
+
+ ts = &__get_cpu_var(tick_cpu_sched);
+ /*
+ * set ts->inidle unconditionally. even if the system did not
+ * switch to nohz mode the cpu frequency governers rely on the
+ * update of the idle time accounting in tick_nohz_start_idle().
+ */
+ ts->inidle = 1;
+ tick_nohz_stop_sched_tick(ts);
+ rcu_idle_enter();
+
+ local_irq_enable();
+}
+
+/**
+ * tick_nohz_irq_exit - update next tick event from interrupt exit
+ *
+ * When an interrupt fires while we are idle and it doesn't cause
+ * a reschedule, it may still add, modify or delete a timer, enqueue
+ * an RCU callback, etc...
+ * So we need to re-calculate and reprogram the next tick event.
+ */
+void tick_nohz_irq_exit(void)
+{
+ struct tick_sched *ts = &__get_cpu_var(tick_cpu_sched);
+
+ if (!ts->inidle)
+ return;
+
+ tick_nohz_stop_sched_tick(ts);
}
/**
@@ -516,11 +535,13 @@ static void tick_nohz_restart(struct tick_sched *ts, ktime_t now)
}
/**
- * tick_nohz_restart_sched_tick - restart the idle tick from the idle task
+ * tick_nohz_idle_exit - restart the idle tick from the idle task
*
* Restart the idle tick when the CPU is woken up from idle
+ * This also exit the RCU extended quiescent state. The CPU
+ * can use RCU again after this function is called.
*/
-void tick_nohz_restart_sched_tick(void)
+void tick_nohz_idle_exit(void)
{
int cpu = smp_processor_id();
struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu);