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[195.231.44.239]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-499877d7974sm177410715e9.1.2026.08.17.00.27.46 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 17 Aug 2026 00:27:46 -0700 (PDT) Message-ID: Date: Mon, 17 Aug 2026 09:27:45 +0200 Precedence: bulk X-Mailing-List: mptcp@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH mptcp-next RFC 2/3] mptcp: reject MP_JOIN earlier To: "Matthieu Baerts (NGI0)" , MPTCP Linux Cc: Chenguang Zhao , gang.yan@linux.dev References: <20260814-mptcp-reset-mpj-early-v1-0-3ca3260f9474@kernel.org> <20260814-mptcp-reset-mpj-early-v1-2-3ca3260f9474@kernel.org> From: Paolo Abeni In-Reply-To: <20260814-mptcp-reset-mpj-early-v1-2-3ca3260f9474@kernel.org> X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: ezjEdMgmP7DqO1d_WCHNrFZndnl5J0ObC6ubv7ZMVUo_1786951668 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 8/14/26 8:31 PM, Matthieu Baerts (NGI0) wrote: > @@ -91,12 +92,22 @@ static struct mptcp_sock *subflow_token_join_request(struct request_sock *req) > msk = mptcp_token_get_sock(sock_net(req_to_sk(req)), subflow_req->token); > if (!msk) { > SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINNOTOKEN); > + *reason = MPTCP_RST_EMPTCP; > + return NULL; > + } > + > + /* Stop it early if the subflow cannot be accepted */ > + if (!mptcp_can_accept_new_subflow(msk)) { Side note: the above is inherently racy, the consistency safeguard is given by the fallback check at finish_join time. Minor nit: I'm not sure this check belongs here or in subflow_check_req(). The latter option would avoid the additional argument and possibly produce a smaller diff (and smaller code). /P