netdev - Re: [PATCH net-next v4 5/6] mptcp: support rstreason for passive reset

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Date: Tue, 16 Apr 2024 08:33:24 +0200
From: Eric Dumazet <edumazet@...gle.com>
To: Jason Xing <kerneljasonxing@...il.com>
Cc: dsahern@...nel.org, matttbe@...nel.org, martineau@...nel.org, 
	geliang@...nel.org, kuba@...nel.org, pabeni@...hat.com, davem@...emloft.net, 
	rostedt@...dmis.org, mhiramat@...nel.org, mathieu.desnoyers@...icios.com, 
	atenart@...nel.org, mptcp@...ts.linux.dev, netdev@...r.kernel.org, 
	Jason Xing <kernelxing@...cent.com>
Subject: Re: [PATCH net-next v4 5/6] mptcp: support rstreason for passive reset

On Thu, Apr 11, 2024 at 1:57 PM Jason Xing <kerneljasonxing@...il.com> wrote:
>
> From: Jason Xing <kernelxing@...cent.com>
>
> It relys on what reset options in the skb are as rfc8684 says. Reusing
> this logic can save us much energy. This patch replaces most of the prior
> NOT_SPECIFIED reasons.
>
> Signed-off-by: Jason Xing <kernelxing@...cent.com>
> ---
>  net/mptcp/subflow.c | 20 +++++++++++++++-----
>  1 file changed, 15 insertions(+), 5 deletions(-)
>
> diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c
> index ba0a252c113f..25eaad94cb79 100644
> --- a/net/mptcp/subflow.c
> +++ b/net/mptcp/subflow.c
> @@ -308,8 +308,12 @@ static struct dst_entry *subflow_v4_route_req(const struct sock *sk,
>                 return dst;
>
>         dst_release(dst);
> -       if (!req->syncookie)
> -               tcp_request_sock_ops.send_reset(sk, skb, SK_RST_REASON_NOT_SPECIFIED);
> +       if (!req->syncookie) {
> +               struct mptcp_ext *mpext = mptcp_get_ext(skb);
> +               enum sk_rst_reason reason = convert_mptcp_reason(mpext->reset_reason);
> +
> +               tcp_request_sock_ops.send_reset(sk, skb, reason);
> +       }
>         return NULL;
>  }
>
> @@ -375,8 +379,12 @@ static struct dst_entry *subflow_v6_route_req(const struct sock *sk,
>                 return dst;
>
>         dst_release(dst);
> -       if (!req->syncookie)
> -               tcp6_request_sock_ops.send_reset(sk, skb, SK_RST_REASON_NOT_SPECIFIED);
> +       if (!req->syncookie) {
> +               struct mptcp_ext *mpext = mptcp_get_ext(skb);
> +               enum sk_rst_reason reason = convert_mptcp_reason(mpext->reset_reason);
> +
> +               tcp6_request_sock_ops.send_reset(sk, skb, reason);
> +       }
>         return NULL;
>  }
>  #endif
> @@ -783,6 +791,7 @@ static struct sock *subflow_syn_recv_sock(const struct sock *sk,
>         bool fallback, fallback_is_fatal;
>         struct mptcp_sock *owner;
>         struct sock *child;
> +       enum sk_rst_reason reason;

reverse xmas tree ?

>
>         pr_debug("listener=%p, req=%p, conn=%p", listener, req, listener->conn);
>
> @@ -911,7 +920,8 @@ static struct sock *subflow_syn_recv_sock(const struct sock *sk,
>         tcp_rsk(req)->drop_req = true;
>         inet_csk_prepare_for_destroy_sock(child);
>         tcp_done(child);
> -       req->rsk_ops->send_reset(sk, skb, SK_RST_REASON_NOT_SPECIFIED);
> +       reason = convert_mptcp_reason(mptcp_get_ext(skb)->reset_reason);
> +       req->rsk_ops->send_reset(sk, skb, reason);
>
>         /* The last child reference will be released by the caller */
>         return child;
> --
> 2.37.3
>