linux-kernel - Re: [PATCH net-next 1/2] pppoe: remove rwlock usage

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Message-ID: <CALW65jZwrO5hQs_rm1Qo_+p-6yiKm+AdC9ZjkfjZnoWAm+i=Bg@mail.gmail.com>
Date: Tue, 26 Aug 2025 16:34:45 +0800
From: Qingfang Deng <dqfext@...il.com>
To: Eric Dumazet <edumazet@...gle.com>
Cc: Michal Ostrowski <mostrows@...thlink.net>, Andrew Lunn <andrew+netdev@...n.ch>, 
	"David S. Miller" <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>, 
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH net-next 1/2] pppoe: remove rwlock usage

On Tue, Aug 26, 2025 at 3:33 PM Eric Dumazet <edumazet@...gle.com> wrote:
> Are you sure that RCU rules make sure sk_refcnt can not be zero ?
>
> sock_hold()  will crash otherwise.
>
> if (po && !refcount_inc_not_zero(&sk_pppox(po)->sk_refcnt))
>     po = NULL;
>
> I will send fixes to drivers/net/pptp.c, net/l2tp/l2tp_ppp.c,
> net/phonet/socket.c, net/qrtr/af_qrtr.c, net/tipc/socket.c

Nice catch. I'll send a v2 with your fix. Thanks!