netdev - Re: [PATCH net] l2tp: prevent lockdep issue in l2tp_tunnel

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Date:   Wed, 18 Jan 2023 09:10:01 -0800
From:   Cong Wang <xiyou.wangcong@...il.com>
To:     Eric Dumazet <edumazet@...gle.com>
Cc:     "David S . Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>, netdev@...r.kernel.org,
        eric.dumazet@...il.com,
        syzbot+bbd35b345c7cab0d9a08@...kaller.appspotmail.com,
        Cong Wang <cong.wang@...edance.com>,
        Guillaume Nault <gnault@...hat.com>
Subject: Re: [PATCH net] l2tp: prevent lockdep issue in l2tp_tunnel_register()

On Tue, Jan 17, 2023 at 11:01:31AM +0000, Eric Dumazet wrote:
> lockdep complains with the following lock/unlock sequence:
> 
>      lock_sock(sk);
>      write_lock_bh(&sk->sk_callback_lock);
> [1]  release_sock(sk);
> [2]  write_unlock_bh(&sk->sk_callback_lock);
> 
> We need to swap [1] and [2] to fix this issue.
> 
> Fixes: 0b2c59720e65 ("l2tp: close all race conditions in l2tp_tunnel_register()")
> Reported-by: syzbot+bbd35b345c7cab0d9a08@...kaller.appspotmail.com
> Signed-off-by: Eric Dumazet <edumazet@...gle.com>
> Link: https://lore.kernel.org/netdev/20230114030137.672706-1-xiyou.wangcong@gmail.com/T/#m1164ff20628671b0f326a24cb106ab3239c70ce3
> Cc: Cong Wang <cong.wang@...edance.com>
> Cc: Guillaume Nault <gnault@...hat.com>

Oops, my bad.

Acked-by: Cong Wang <cong.wang@...edance.com>

Thanks.