/*
* The idle thread. There's no useful work to be
* done, so just try to conserve power and have a
* low exit latency (ie sit in a loop waiting for
* somebody to say that they'd like to reschedule)
*/
void cpu_idle(void)
{
int cpu = smp_processor_id();
current_thread_info()->status |= TS_POLLING;
/* endless idle loop with no priority at all */
while (1) {
tick_nohz_stop_sched_tick();
while (!need_resched()) {
check_pgt_cache();
rmb();
if (rcu_pending(cpu))
rcu_check_callbacks(cpu, 0);
if (cpu_is_offline(cpu))
play_dead();
local_irq_disable();
__get_cpu_var(irq_stat).idle_timestamp = jiffies;
/* Don't trace irqs off for idle */
stop_critical_timings();
pm_idle();
start_critical_timings();
}
tick_nohz_restart_sched_tick();
preempt_enable_no_resched();
schedule();
preempt_disable();
}
}
void cpu_idle(void)
{
int cpu = smp_processor_id();
boot_init_stack_canary();
current_thread_info()->status |= TS_POLLING;
while (1) {
tick_nohz_stop_sched_tick(1);
while (!need_resched()) {
check_pgt_cache();
rmb();
if (cpu_is_offline(cpu))
play_dead();
local_irq_disable();
stop_critical_timings();
pm_idle();
start_critical_timings();
}
tick_nohz_restart_sched_tick();
preempt_enable_no_resched();
schedule();
preempt_disable();
}
}
/*
* The idle thread. There's no useful work to be
* done, so just try to conserve power and have a
* low exit latency (ie sit in a loop waiting for
* somebody to say that they'd like to reschedule)
*/
void cpu_idle(void)
{
int cpu = smp_processor_id();
/*
* If we're the non-boot CPU, nothing set the stack canary up
* for us. CPU0 already has it initialized but no harm in
* doing it again. This is a good place for updating it, as
* we wont ever return from this function (so the invalid
* canaries already on the stack wont ever trigger).
*/
boot_init_stack_canary();
current_thread_info()->status |= TS_POLLING;
/* endless idle loop with no priority at all */
while (1) {
tick_nohz_stop_sched_tick(1);
while (!need_resched()) {
check_pgt_cache();
rmb();
if (cpu_is_offline(cpu))
play_dead();
local_irq_disable();
enter_idle();
/* Don't trace irqs off for idle */
stop_critical_timings();
pm_idle();
start_critical_timings();
/*
* In many cases the interrupt that ended idle
* has already called exit_idle. But some idle
* loops can be woken up without interrupt.
*/
__exit_idle();
}
tick_nohz_restart_sched_tick();
preempt_enable_no_resched();
schedule();
preempt_disable();
}
}
/*
* The idle thread, has rather strange semantics for calling pm_idle,
* but this is what x86 does and we need to do the same, so that
* things like cpuidle get called in the same way. The only difference
* is that we always respect 'hlt_counter' to prevent low power idle.
*/
void cpu_idle(void)
{
local_fiq_enable();
/* endless idle loop with no priority at all */
while (1) {
idle_notifier_call_chain(IDLE_START);
tick_nohz_idle_enter();
rcu_idle_enter();
while (!need_resched()) {
/*
* We need to disable interrupts here
* to ensure we don't miss a wakeup call.
*/
local_irq_disable();
#ifdef CONFIG_PL310_ERRATA_769419
wmb();
#endif
if (hlt_counter) {
local_irq_enable();
cpu_relax();
} else if (!need_resched()) {
stop_critical_timings();
if (cpuidle_idle_call())
pm_idle();
start_critical_timings();
/*
* pm_idle functions must always
* return with IRQs enabled.
*/
WARN_ON(irqs_disabled());
} else
local_irq_enable();
}
rcu_idle_exit();
tick_nohz_idle_exit();
idle_notifier_call_chain(IDLE_END);
schedule_preempt_disabled();
#ifdef CONFIG_HOTPLUG_CPU
if (cpu_is_offline(smp_processor_id()))
cpu_die();
#endif
}
}
