/*
* 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();
}
}
/*
* Check to see if any future RCU-related work will need to be done
* by the current CPU, even if none need be done immediately, returning
* 1 if so. This function is part of the RCU implementation; it is -not-
* an exported member of the RCU API.
*/
int rcu_needs_cpu(int cpu)
{
struct rcu_data *rdp = &per_cpu(rcu_data, cpu);
struct rcu_data *rdp_bh = &per_cpu(rcu_bh_data, cpu);
return (!!rdp->curlist || !!rdp_bh->curlist || rcu_pending(cpu));
}
asmlinkage void do_softirq(void)
{
unsigned int i, cpu;
unsigned long pending;
for ( ; ; )
{
/*
* Initialise @cpu on every iteration: SCHEDULE_SOFTIRQ may move
* us to another processor.
*/
cpu = smp_processor_id();
if ( rcu_pending(cpu) )
rcu_check_callbacks(cpu);
if ( (pending = softirq_pending(cpu)) == 0 )
break;
i = find_first_set_bit(pending);
clear_bit(i, &softirq_pending(cpu));
(*softirq_handlers[i])();
}
}
