softirq 処理はいつ行われるか のバックアップ(No.2)

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static struct smp_hotplug_thread softirq_threads = {
        .store                  = &ksoftirqd,
        .thread_should_run      = ksoftirqd_should_run,
        .thread_fn              = run_ksoftirqd,
        .thread_comm            = "ksoftirqd/%u",
};

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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;
        }
 
        rcu_bh_qs();
        local_irq_disable();
 
        pending = local_softirq_pending();
        if (pending) {
                if (time_before(jiffies, end) && !need_resched() &&
                    --max_restart)
                        goto restart;
 
                wakeup_softirqd();
        }