__do_softirq

#endif
 
asmlinkage __visible void __softirq_entry __do_softirq(void)
{
    unsigned long end = jiffies + MAX_SOFTIRQ_TIME;
    unsigned long old_flags = current->flags;
    int max_restart = MAX_SOFTIRQ_RESTART;
    struct softirq_action *h;
    bool in_hardirq;
    __u32 pending;
    int softirq_bit;
 
    /*
     * Mask out PF_MEMALLOC as the current task context is borrowed for the
     * softirq. A softirq handled, such as network RX, might set PF_MEMALLOC
     * again if the socket is related to swapping.
     */
    current->flags &= ~PF_MEMALLOC;
 
    pending = local_softirq_pending();
    account_irq_enter_time(current);
 
    __local_bh_disable_ip(_RET_IP_, SOFTIRQ_OFFSET);
    in_hardirq = lockdep_softirq_start();
 
restart:
    /* Reset the pending bitmask before enabling irqs */
    set_softirq_pending(0);
 
    local_irq_enable();
 
    h = softirq_vec;
 
    while ((softirq_bit = ffs(pending))) {
        unsigned int vec_nr;
        int prev_count;
 
        h += softirq_bit - 1;
 
        vec_nr = h - softirq_vec;
        prev_count = preempt_count();
 
        kstat_incr_softirqs_this_cpu(vec_nr);
 
        trace_softirq_entry(vec_nr);
        h->action(h);
        trace_softirq_exit(vec_nr);
        if (unlikely(prev_count != preempt_count())) {
            pr_err("huh, entered softirq %u %s %p with preempt_count %08x, exited with %08x?\n",
                   vec_nr, softirq_to_name[vec_nr], h->action,
                   prev_count, preempt_count());
            preempt_count_set(prev_count);
        }
        h++;
        pending >>= softirq_bit;
    }
 
    if (__this_cpu_read(ksoftirqd) == current)
        rcu_softirq_qs();
    local_irq_disable();
 
    pending = local_softirq_pending();
    if (pending) {
        if (time_before(jiffies, end) && !need_resched() &&
            --max_restart)
            goto restart;
 
        wakeup_softirqd();
    }
 
    lockdep_softirq_end(in_hardirq);
    account_irq_exit_time(current);
    __local_bh_enable(SOFTIRQ_OFFSET);
    WARN_ON_ONCE(in_interrupt());
    current_restore_flags(old_flags, PF_MEMALLOC);
}
函数源码
