/*
* 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();
}
}
void arch_cpu_idle_enter(void)
{
local_touch_nmi();
enter_idle();
}
