linux-kernel - Re: [PATCH net-next v4 2/2] tcp: Free TCP-AO/TCP-MD5 info/keys without RCU

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Message-ID: <CAAVpQUCiaQ7yr+5xLYVaRp6E2pzNDwSiznEOkmd5wS-SAosUng@mail.gmail.com>
Date: Wed, 3 Sep 2025 14:25:47 -0700
From: Kuniyuki Iwashima <kuniyu@...gle.com>
To: dima@...sta.com
Cc: Eric Dumazet <edumazet@...gle.com>, Neal Cardwell <ncardwell@...gle.com>, 
	"David S. Miller" <davem@...emloft.net>, David Ahern <dsahern@...nel.org>, 
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>, Simon Horman <horms@...nel.org>, 
	Bob Gilligan <gilligan@...sta.com>, Salam Noureddine <noureddine@...sta.com>, 
	Dmitry Safonov <0x7f454c46@...il.com>, netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH net-next v4 2/2] tcp: Free TCP-AO/TCP-MD5 info/keys
 without RCU

On Wed, Sep 3, 2025 at 1:30 PM Dmitry Safonov via B4 Relay
<devnull+dima.arista.com@...nel.org> wrote:
>
> From: Dmitry Safonov <dima@...sta.com>
>
> Now that the destruction of info/keys is delayed until the socket
> destructor, it's safe to use kfree() without an RCU callback.
> As either socket was yet in TCP_CLOSE state or the socket refcounter is

Why either ?  Maybe I'm missing but is there a path where
->unhash() is called without changing the state to TCP_CLOSE ?


> zero and no one can discover it anymore, it's safe to release memory
> straight away.
> Similar thing was possible for twsk already.
>
> Signed-off-by: Dmitry Safonov <dima@...sta.com>

Change itself looks good.

Reviewed-by: Kuniyuki Iwashima <kuniyu@...gle.com>