netdev - Re: [PATCH net-next 1/2] mptcp: annotate a data-race around sysctl_tcp

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Message-ID: <51583ac1-3717-269a-907f-992e009dc045@kernel.org>
Date: Fri, 8 Mar 2024 12:26:09 -0800 (PST)
From: Mat Martineau <martineau@...nel.org>
To: Jason Xing <kerneljasonxing@...il.com>
cc: edumazet@...gle.com, dsahern@...nel.org, 
    Matthieu Baerts <matttbe@...nel.org>, geliang@...nel.org, kuba@...nel.org, 
    Paolo Abeni <pabeni@...hat.com>, davem@...emloft.net, 
    mptcp@...ts.linux.dev, netdev@...r.kernel.org, 
    Jason Xing <kernelxing@...cent.com>
Subject: Re: [PATCH net-next 1/2] mptcp: annotate a data-race around
 sysctl_tcp_wmem[0]

On Fri, 8 Mar 2024, Jason Xing wrote:

> From: Jason Xing <kernelxing@...cent.com>
>
> It's possible that writer and the reader can manipulate the same
> sysctl knob concurrently. Using READ_ONCE() to prevent reading
> an old value.
>
> Signed-off-by: Jason Xing <kernelxing@...cent.com>
> ---
> net/mptcp/protocol.h | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
> index f16edef6026a..a10ebf3ee10a 100644
> --- a/net/mptcp/protocol.h
> +++ b/net/mptcp/protocol.h
> @@ -850,7 +850,7 @@ static inline void __mptcp_sync_sndbuf(struct sock *sk)
> 	if (sk->sk_userlocks & SOCK_SNDBUF_LOCK)
> 		return;
>
> -	new_sndbuf = sock_net(sk)->ipv4.sysctl_tcp_wmem[0];
> +	new_sndbuf = READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_wmem[0]);
> 	mptcp_for_each_subflow(mptcp_sk(sk), subflow) {
> 		ssk_sndbuf =  READ_ONCE(mptcp_subflow_tcp_sock(subflow)->sk_sndbuf);
>

Looks good to me, thanks Jason.

Reviewed-by: Mat Martineau <martineau@...nel.org>