C++ do_softirq函数代码示例

void __local_bh_enable_ip(unsigned long ip, unsigned int cnt)
{
	WARN_ON_ONCE(in_irq() || irqs_disabled());
#ifdef CONFIG_TRACE_IRQFLAGS
	local_irq_disable();
#endif
	/*
	 * Are softirqs going to be turned on now:
	 */
	if (softirq_count() == SOFTIRQ_DISABLE_OFFSET)
		trace_softirqs_on(ip);
	/*
	 * Keep preemption disabled until we are done with
	 * softirq processing:
	 */
	preempt_count_sub(cnt - 1);

	if (unlikely(!in_interrupt() && local_softirq_pending())) {
		/*
		 * Run softirq if any pending. And do it in its own stack
		 * as we may be calling this deep in a task call stack already.
		 */
		do_softirq();
	}

	preempt_count_dec();
#ifdef CONFIG_TRACE_IRQFLAGS
	local_irq_enable();
#endif
	preempt_check_resched();
}

asmlinkage void do_IRQ(int irq, struct pt_regs * regs)
{
	struct irqaction *action;
	int do_random, cpu;

        cpu = smp_processor_id();
        irq_enter(cpu);
	kstat.irqs[cpu][irq]++;

	action = irq_action[irq];
        if (action) {
                if (!(action->flags & SA_INTERRUPT))
                        __sti();
                action = irq_action[irq];
                do_random = 0;
                do {
                        do_random |= action->flags;
                        action->handler(irq, action->dev_id, regs);
                        action = action->next;
                } while (action);
                if (do_random & SA_SAMPLE_RANDOM)
                        add_interrupt_randomness(irq);
                __cli();
        }
        irq_exit(cpu);

	if (softirq_pending(cpu))
                do_softirq();

        /* unmasking and bottom half handling is done magically for us. */
}

void smp_apic_timer_interrupt(struct pt_regs * regs)
{
	int cpu = smp_processor_id();

	/*
	 * the NMI deadlock-detector uses this.
	 */
	apic_timer_irqs[cpu]++;

	/*
	 * NOTE! We'd better ACK the irq immediately,
	 * because timer handling can be slow.
	 */
	ack_APIC_irq();
	/*
	 * update_process_times() expects us to have done irq_enter().
	 * Besides, if we don't timer interrupts ignore the global
	 * interrupt lock, which is the WrongThing (tm) to do.
	 */
	irq_enter(cpu, 0);
	smp_local_timer_interrupt(regs);
	irq_exit(cpu, 0);

	if (softirq_pending(cpu))
		do_softirq();
}

void irq_exit(void)
{
	account_system_vtime(current);
	trace_hardirq_exit();
	sub_preempt_count(IRQ_EXIT_OFFSET);
	if (!in_interrupt() && local_softirq_pending())
		do_softirq();
}

void __domain_crash_synchronous(void)
{
    __domain_crash(current->domain);

    vcpu_end_shutdown_deferral(current);

    for ( ; ; )
        do_softirq();
}

void indy_r4k_timer_interrupt (struct pt_regs *regs)
{
	static const int INDY_R4K_TIMER_IRQ = 7;
	int cpu = smp_processor_id();

	r4k_timer_interrupt (INDY_R4K_TIMER_IRQ, NULL, regs);

	if (softirq_pending(cpu))
		do_softirq();
}

static void softirq_task_function(void *context)
{
	while (true) {
		do_softirq();
		g_n_raises--;
		if (g_n_raises == 0 || local_softirq_pending() == 0) {
			g_n_raises = 0;
			lib_task_wait();
		}
	}
}

void local_bh_enable_ip(unsigned long ip)
{
	WARN_ON_ONCE(in_irq() || irqs_disabled());
	sub_preempt_count(SOFTIRQ_DISABLE_OFFSET - 1);

	if (unlikely(!in_interrupt() && local_softirq_pending()))
		do_softirq();
	dec_preempt_count();

	preempt_check_resched();
}

void rt_timer_interrupt(struct pt_regs *regs)
{
	int cpu = smp_processor_id();
	int cpuA = ((cputoslice(cpu)) == 0);
	int irq = IP27_TIMER_IRQ;

	irq_enter(cpu, irq);
	write_lock(&xtime_lock);

again:
	LOCAL_HUB_S(cpuA ? PI_RT_PEND_A : PI_RT_PEND_B, 0);	/* Ack  */
	ct_cur[cpu] += CYCLES_PER_JIFFY;
	LOCAL_HUB_S(cpuA ? PI_RT_COMPARE_A : PI_RT_COMPARE_B, ct_cur[cpu]);

	if (LOCAL_HUB_L(PI_RT_COUNT) >= ct_cur[cpu])
		goto again;

	kstat.irqs[cpu][irq]++;		/* kstat only for bootcpu? */

	if (cpu == 0)
		do_timer(regs);

#ifdef CONFIG_SMP
	update_process_times(user_mode(regs));
#endif /* CONFIG_SMP */

	/*
	 * If we have an externally synchronized Linux clock, then update
	 * RTC clock accordingly every ~11 minutes. Set_rtc_mmss() has to be
	 * called as close as possible to when a second starts.
	 */
	if ((time_status & STA_UNSYNC) == 0 &&
	    xtime.tv_sec > last_rtc_update + 660) {
		if (xtime.tv_usec >= 1000000 - ((unsigned) tick) / 2) {
			if (set_rtc_mmss(xtime.tv_sec + 1) == 0)
				last_rtc_update = xtime.tv_sec;
			else
				last_rtc_update = xtime.tv_sec - 600;
		} else if (xtime.tv_usec <= ((unsigned) tick) / 2) {
			if (set_rtc_mmss(xtime.tv_sec) == 0)
				last_rtc_update = xtime.tv_sec;
			else
				last_rtc_update = xtime.tv_sec - 600;
		}
        }

	write_unlock(&xtime_lock);
	irq_exit(cpu, irq);

	if (softirq_pending(cpu))
		do_softirq();
}

void local_bh_enable(void)
{
	WARN_ON(irqs_disabled());
	/*
	 * Keep preemption disabled until we are done with
	 * softirq processing:
 	 */
	preempt_count() -= SOFTIRQ_OFFSET - 1;

	if (unlikely(!in_interrupt() && local_softirq_pending()))
		do_softirq();

	dec_preempt_count();
	preempt_check_resched();
}

static inline void invoke_softirq(void)
{
	if (!force_irqthreads) {
#ifdef __ARCH_IRQ_EXIT_IRQS_DISABLED
		__do_softirq();
#else
		do_softirq();
#endif
	} else {
		__local_bh_disable((unsigned long)__builtin_return_address(0),
				SOFTIRQ_OFFSET);
		wakeup_softirqd();
		__local_bh_enable(SOFTIRQ_OFFSET);
	}
}

asmlinkage void ll_timer_interrupt(int irq, struct pt_regs *regs)
{
	int cpu = smp_processor_id();

	irq_enter(cpu, irq);
	kstat.irqs[cpu][irq]++;

	/* we keep interrupt disabled all the time */
	timer_interrupt(irq, NULL, regs);
	
	irq_exit(cpu, irq);

	if (softirq_pending(cpu))
		do_softirq();
}

static inline void invoke_softirq(void)
{
	if (!force_irqthreads) {
		/*
		 * We can safely execute softirq on the current stack if
		 * it is the irq stack, because it should be near empty
		 * at this stage. But we have no way to know if the arch
		 * calls irq_exit() on the irq stack. So call softirq
		 * in its own stack to prevent from any overrun on top
		 * of a potentially deep task stack.
		 */
		do_softirq();
	} else {
		wakeup_softirqd();
	}
}

static int ksoftirqd(void * __bind_cpu)
{
	set_user_nice(current, 19);
	current->flags |= PF_NOFREEZE;

	set_current_state(TASK_INTERRUPTIBLE);

	while (!kthread_should_stop()) {
		preempt_disable();
		if (!local_softirq_pending()) {
			preempt_enable_no_resched();
			schedule();
			preempt_disable();
		}

		__set_current_state(TASK_RUNNING);

		while (local_softirq_pending()) {
			/* Preempt disable stops cpu going offline.
			   If already offline, we'll be on wrong CPU:
			   don't process */
			if (cpu_is_offline((long)__bind_cpu))
				goto wait_to_die;
			do_softirq();
			preempt_enable_no_resched();
			cond_resched();
			preempt_disable();
			rcu_qsctr_inc((long)__bind_cpu);
		}
		preempt_enable();
		set_current_state(TASK_INTERRUPTIBLE);
	}
	__set_current_state(TASK_RUNNING);
	return 0;

wait_to_die:
	preempt_enable();
	/* Wait for kthread_stop */
	set_current_state(TASK_INTERRUPTIBLE);
	while (!kthread_should_stop()) {
		schedule();
		set_current_state(TASK_INTERRUPTIBLE);
	}
	__set_current_state(TASK_RUNNING);
	return 0;
}

void idle_loop(void)
{
    for ( ; ; )
    {
        if ( cpu_is_offline(smp_processor_id()) )
            stop_cpu();

        local_irq_disable();
        if ( cpu_is_haltable(smp_processor_id()) )
        {
            dsb(sy);
            wfi();
        }
        local_irq_enable();

        do_tasklet();
        do_softirq();
    }
}