Re: [RFC PATCH 0/2] net: threadable napi poll loop

[Eric Dumazet]

On Wed, 2016-05-11 at 07:40 -0700, Eric Dumazet wrote:
> On Wed, May 11, 2016 at 6:13 AM, Hannes Frederic Sowa
> <hannes@xxxxxxxxxxxxxxxxxxx> wrote:
> 
> > This looks racy to me as the ksoftirqd could be in the progress to stop
> > and we would miss another softirq invocation.
> 
> Looking at smpboot_thread_fn(), it looks fine :
> 
>                 if (!ht->thread_should_run(td->cpu)) {
>                         preempt_enable_no_resched();
>                         schedule();
>                 } else {
>                         __set_current_state(TASK_RUNNING);
>                         preempt_enable();
>                         ht->thread_fn(td->cpu);
>                 }

BTW, I wonder why we pass td->cpu as argument to ht->thread_fn(td->cpu)

This always should be the current processor id.

Or do we have an issue because we ignore it in :

static int ksoftirqd_should_run(unsigned int cpu)
{
        return local_softirq_pending();
}