linux-kernel - Re: [PATCH net-next] net: ppp: remove ppp->closing check

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Message-ID: <CALW65jaKn7HQth6oYYHWYvg7CTZJj2QH66nHyo41BNjAA15Y7g@mail.gmail.com>
Date: Fri, 8 Nov 2024 14:09:37 +0800
From: Qingfang Deng <dqfext@...il.com>
To: Paolo Abeni <pabeni@...hat.com>
Cc: Andrew Lunn <andrew+netdev@...n.ch>, "David S. Miller" <davem@...emloft.net>, 
	Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, linux-ppp@...r.kernel.org, 
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH net-next] net: ppp: remove ppp->closing check

Hi Paolo,

On Thu, Nov 7, 2024 at 8:08 PM Paolo Abeni <pabeni@...hat.com> wrote:
>
>
>
> On 11/4/24 10:24, Qingfang Deng wrote:
> > ppp->closing was used to test if an interface is closing down. But upon
> > .ndo_uninit() where ppp->closing is set to 1, dev_close() is already
> > called to bring down an interface and a synchronize_net() guarantees
> > that no pending TX/RX can take place, so the check is unnecessary.
> > Remove the check.
>
> I'm unsure we can remote such check. The TX callback can be triggered
> even from a write on the controlling file, and it looks like such file
> will be untouched by uninit.

ppp_release (when the file is closed) calls unregister_netdevice, and
no more writes can happen after that.

>
> Cheers,
>
> Paolo
>