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

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Message-ID: <CANn89i+Op8UsvrsZKKzHfC5j6gLMmY1ZbCg=OY8o4oW8RT5sxg@mail.gmail.com>
Date:	Wed, 11 May 2016 07:40:13 -0700
From:	Eric Dumazet <edumazet@...gle.com>
To:	Hannes Frederic Sowa <hannes@...essinduktion.org>
Cc:	Peter Zijlstra <peterz@...radead.org>,
	Eric Dumazet <eric.dumazet@...il.com>,
	Paolo Abeni <pabeni@...hat.com>,
	netdev <netdev@...r.kernel.org>,
	"David S. Miller" <davem@...emloft.net>,
	Jiri Pirko <jiri@...lanox.com>,
	Daniel Borkmann <daniel@...earbox.net>,
	Alexei Starovoitov <ast@...mgrid.com>,
	Alexander Duyck <aduyck@...antis.com>,
	Tom Herbert <tom@...bertland.com>,
	Ingo Molnar <mingo@...nel.org>, Rik van Riel <riel@...hat.com>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [RFC PATCH 0/2] net: threadable napi poll loop

On Wed, May 11, 2016 at 6:13 AM, Hannes Frederic Sowa
<hannes@...essinduktion.org> 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);
                }