netdev - Re: [PATCH net] net: fix hangup on napi

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Date:   Fri, 9 Apr 2021 08:15:53 -0700
From:   Jakub Kicinski <kuba@...nel.org>
To:     Paolo Abeni <pabeni@...hat.com>
Cc:     netdev@...r.kernel.org, Eric Dumazet <edumazet@...gle.com>,
        Wei Wang <weiwan@...gle.com>,
        "David S. Miller" <davem@...emloft.net>
Subject: Re: [PATCH net] net: fix hangup on napi_disable for threaded napi

On Fri, 09 Apr 2021 11:24:07 +0200 Paolo Abeni wrote:
> I think it can be simplified as the following - if NAPIF_STATE_DISABLE
> is set, napi_threaded_poll()/__napi_poll() will return clearing the
> SCHEDS bits after trying to poll the device:

Indeed!

> diff --git a/net/core/dev.c b/net/core/dev.c
> index d9db02d4e044..5cb6f411043d 100644
> --- a/net/core/dev.c
> +++ b/net/core/dev.c
> @@ -6985,7 +6985,7 @@ static int napi_thread_wait(struct napi_struct *napi)
>  
>         set_current_state(TASK_INTERRUPTIBLE);
>  
> -       while (!kthread_should_stop() && !napi_disable_pending(napi)) {
> +       while (!kthread_should_stop()) {
>                 /* Testing SCHED_THREADED bit here to make sure the current
>                  * kthread owns this napi and could poll on this napi.
>                  * Testing SCHED bit is not enough because SCHED bit might be
> 
> ---
> 
> And works as intended here. I'll submit that formally, unless there are
> objection.

Please and thank you!