From nobody Thu Nov 5 07:28:49 2026 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=74.125.82.172 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793166111; b=XSa44DBlzR3Q8iqpcHIXzT1CfvTdt2jTfbySRvEuinQqJG6sTHJ8D5Z087yQz6cmg7zE fmtz9pvTmSfCUSzjw0MCPKfPsGeErffisNmdtMr3XHSK1dgWYxUeGswse6mpikMuoTFYa dG73KGtNYbsbEXyMdrseLc1BWALCHjjEn1vdPDncJYk+m6aETVSe/5+flldL+V3zMvHe5 D7KQo2vexpbkb/SyPUMNYJFitJ3LXGaeBgnmxInyJcn5ninZIpX1UJrVHW7Yd6h5zUtAs IJYmbJCUP8nnSXCXs4Fb615SAjqmb+b4HhXYo8cB7dXQ9YrXxg0VAquSdEpIi+cl3jA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793166111; h=DMARC-Filter:Received:DKIM-Signature:X-Google-DKIM-Signature: X-Gm-Message-State:X-Gm-Gg:X-Received:Received:From:To:Cc:Subject: Date:Message-Id:X-Mailer:In-Reply-To:References:MIME-Version: Content-Transfer-Encoding; bh=XwlldahLZl6u6KBDX9l7n8vOmnvTZvhZdUFA/a8ErDA=; b=wZ5yN6zBQn1os5Hj4uqMIGz47Iw7wSYJ1oB4F1LfHlIPG27LOZIXjCeeVa/QZzeoTSbB V0OERd/2Rz9p7z/MA/NOgpY3YZEntUblMxkSoK9f3ubGy67u2RE30Akei9bbz0yfIq7G7 1ODJVS9Dp5++j2K0ygu5xBaEVY+iyOMPZZ2BP0UpEW4pMUv89YpVAbWmkwpxhH2N/kNLR jk7i/TGmaCyriEWBF+TMJRgDa4IrXlAmNE8mvtOwmDsDwTMNEXkK0EicdeQMxMHt9tXEv gmKHtsNwR29WDkuJNoX98oyqQk7l32TOgf6kj582Vi/syfnnWn7WzkFLOhssrxD1DKA== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256 header.s=20260707 header.b=JN8zjv2K; arc=none smtp.remote-ip=74.125.82.172 Received: from mail-dy1-f172.google.com (mail-dy1-f172.google.com [74.125.82.172]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id CE166606A31A for ; Wed, 28 Oct 2026 05:41:50 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org CE166606A31A Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256 header.s=20260707 header.b=JN8zjv2K Received: by mail-dy1-f172.google.com with SMTP id 5a478bee46e88-36a121bb8c2so786827eec.0 for ; Tue, 27 Oct 2026 22:41:50 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20260707; t=1793166110; x=1793770910; darn=lists.linux.dev; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to:content-type; bh=XwlldahLZl6u6KBDX9l7n8vOmnvTZvhZdUFA/a8ErDA=; b=JN8zjv2KLs/7DVad0K/a5RReIyD2LSA67YZUrffvM+kc0LsxPSXaoR3gM5lghHLNd7 Ob4dDQaD38NR+dR3deDTDmqHYbOAqETykQUMSH1K4vhv6C+IClghHdfiogSX8xWj3qSr j+HMHxlr0iqEcwpCtHNqzNHgpolZbc5E3QRLRhxl/l3+JAAmpNg2GYSG3fD2zP9vz1SJ HnTVoKrJ/LihV8YP4EgdP6jhriTHX0EqgohWNrCvyaX4qrxyoTIYjzWhhh27J2U0eKuZ UVvQNJvbfS+ECfR4QiXUhJ/h2nrHsI2/7Ku5/ookhn44D87sLNXqDAv4nIgvdt3+7rMz 8Fcg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20260707; t=1793166110; x=1793770910; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-gg:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to:content-type; bh=XwlldahLZl6u6KBDX9l7n8vOmnvTZvhZdUFA/a8ErDA=; b=XXWyYJWYhHMI4Izh9QJjS11PsGErSawSvIkjWNA+yiULyupTZhl7mpbZ0rRjU2Aca8 N80fEmwC+HLDok4Ilm1x9/LXy7XQ8M79jG+nU7yOmOOcLPJq5Rsf4jVBNXmwhQ5lqMOE mPlf+17hf677h+PqQGnWc8pDccpaNSKRxfjOxZmwGfon3nSH4Jyzc2F0z6cLaxMUD6uP Fi96baJ+QAaGg0CHQgyufUI1UtzKfGE0FsHcwY2eWdsfXBOCxUBGNvNcaw/gGvS0xnex rZ37O6qSSWdrmWNdkEfmU3n2Kyn4qy1X9xP61r9/xmWqDye5AY9uqRTTBoQCtblrATik bRHA== X-Gm-Message-State: AFq9FYLWOVcDJwfFIwjQ0oKYESIyyKGcMEGfpkqZD5u6xilSB9qnP9/5 5en6czVTGymNA+L55/cKIv3Yta0OYEEn56uriJNYeR/nnknT3KeuqXQRA50Rtg== X-Gm-Gg: AYBFou0lLlfuvBmlv8vN3h8rEMEe4YQBORd5p/nBtMgvdHJmBVpa9Pbo7lJlEaXOpi8 Qt86wv/PBkiNLtsNp5AhZCg9z9zbiBvrlJqC4TGSArCOQr0pYC3Oan76zl+co9KQJXhnBHoYZ3E 8L1k0cS4v98pV2Zp8IqBKM1kj9eryZnY8x8FlMDBFz97Y5GK0gcGOIkO/MT7ALqITuxjwzNBI2h RJLXJSXkmriTIm5ZZMpXryCMN2GLLHIbGL5bTzZPTCFG5TI1ND9tJCrb0u4zTQWr+G2TW3ewYit vwjwnRv+lrzNQgPjWhIiv3doiX+w3EUgjsN6XyS43p8NCmif3qmvGsc966GiiLBiz+kh7pfjVyk YiF+t2e4tqXfWWGqs5cHSc4GrWhAv7ahhNpTHzzyjuYZZpsQ2r1ALXWlnRHgWinU6V8vRc0A+r8 xo+aIOeYI0BAmx+qXLcZzO/M5TKChCN+gvrZ4ElgccyDg21DSRCsbRSIxUSgLdz2rc5WSxrSKzp DDlS+WXivRP9jYn7XOm7EhTpcSWmAKRojc0+9XRTj9HHF9Kh9QaptR4A9mOs2unnsfSmwxI7NTJ +FdELyLUktL71mZlPbbLGn1EFFI0+akeoh1yatfIvIn2ktM2X8u/sTdWGn95psgtvfDz2eyjQk6 2M/V8vHZxoxkSbK2MfNA3R01VL5cvMoPIuApCpKOZkHMi1L0YKyB+OICTZG3kXPEP+a7AG+Us/X njuCrPQjsBJU8L/9Cigeg= X-Received: by 2002:a05:693c:6384:20b0:339:851c:4c1 with SMTP id 5a478bee46e88-36a0f887a20mr6037334eec.18.1793166109762; Tue, 27 Oct 2026 22:41:49 -0700 (PDT) Received: from ramen-dev-security-2.asia-south1-c.c.ramen-dev-345017.internal (90.156.200.35.bc.googleusercontent.com. [35.200.156.90]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-36a237be80csm5860973eec.2.2026.10.27.22.41.48 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 27 Oct 2026 22:41:49 -0700 (PDT) From: Anil Kaushik To: mptcp@lists.linux.dev Cc: Anil Kaushik Subject: [PATCH mptcp-next v12 1/6] selftests: mptcp: connect: retry write() on EAGAIN Date: Wed, 28 Oct 2026 05:41:38 +0000 Message-Id: <20261028054143.3222998-2-anilkaushikwireless@gmail.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20261028054143.3222998-1-anilkaushikwireless@gmail.com> References: <20261028054143.3222998-1-anilkaushikwireless@gmail.com> X-Mailing-List: mptcp@lists.linux.dev List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" mptcp_connect treats any write() error as fatal. But write() can fail with EAGAIN even after poll() said the socket was writable: the MPTCP send buffer shrinks when a subflow is closed. The tool then exits and the transfer fails on both sides. Instead, go back to poll() and wait for more space. If a poll timeout is set, still fail after as many retries, 1ms apart: poll() does not check every cause of EAGAIN. Fixes: 048d19d444be ("mptcp: add basic kselftest for mptcp") Signed-off-by: Anil Kaushik --- Notes: v6: - the comment says the limit only applies with a poll timeout (netdev Sashiko) v5: - no change v4: - count the EAGAIN retries, not ms (Sashiko) - no limit when there is no poll timeout, -t 0 (Sashiko) v3: - do not wait forever on EAGAIN (Sashiko) - wrap lines over 80 columns v2: - Fixes tag .../selftests/net/mptcp/mptcp_connect.c | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) diff --git a/tools/testing/selftests/net/mptcp/mptcp_connect.c b/tools/test= ing/selftests/net/mptcp/mptcp_connect.c index 178d98d91fea..49017d00ab69 100644 --- a/tools/testing/selftests/net/mptcp/mptcp_connect.c +++ b/tools/testing/selftests/net/mptcp/mptcp_connect.c @@ -638,6 +638,7 @@ static int copyfd_io_poll(int infd, int peerfd, int out= fd, .events =3D POLLIN | POLLOUT, }; unsigned int total_wlen =3D 0, total_rlen =3D 0; + int eagain_cnt =3D 0; =20 set_nonblock(peerfd, true); =20 @@ -711,6 +712,22 @@ static int copyfd_io_poll(int infd, int peerfd, int ou= tfd, =20 bw =3D do_rnd_write(peerfd, winfo->buf + winfo->off, winfo->len); if (bw < 0) { + /* POLLOUT does not guarantee that + * the next write will not block: + * the MPTCP send buffer can shrink + * in between, e.g. when a subflow + * is closed. Wait for more space, + * but not forever if a poll timeout + * is set: poll() does not check + * every cause of EAGAIN. + */ + if (errno =3D=3D EAGAIN && + (poll_timeout < 0 || + ++eagain_cnt <=3D poll_timeout)) { + usleep(1000); + continue; + } + /* expected reset, continue to read */ if (cfg_rcv_trunc && (errno =3D=3D ECONNRESET || @@ -723,6 +740,7 @@ static int copyfd_io_poll(int infd, int peerfd, int out= fd, return 111; } =20 + eagain_cnt =3D 0; winfo->off +=3D bw; winfo->len -=3D bw; total_wlen +=3D bw; --=20 2.25.1 From nobody Thu Nov 5 07:28:49 2026 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=74.125.82.169 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793166113; b=WIc1xLrMAyaLT5YPI0fnrlCMYPDNB9cf1YI+pmfmbATbQCbO4ZEyH+xGmuGJp/sOatmy +Zbur8tGTLzK20jcZNic8K2bSIWFx/RuCzi44yK3BWmTBoQvCL5aYlpYvN6FEm2u5H7sF 8g7tQp4E8QJRt7edDcskMwGvk9vXFcpljektIyNac25caLv1JfP2sK4YdHgvvpQMlTVLI ZFCOsTY5kl4T5a77/MZkHj24JXvRvfhXOnb6PVwbM94tnmGucouPpNM7C7+U+ZFlb5pDv lGovyMd11pyff6rI9/wVvQaWd6r6SeErPWiG1tNdGhJ2fHL2ZsHEt3I9YwufCEMRxCQ== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793166113; h=DMARC-Filter:Received:DKIM-Signature:X-Google-DKIM-Signature: X-Gm-Message-State:X-Gm-Gg:X-Received:Received:From:To:Cc:Subject: Date:Message-Id:X-Mailer:In-Reply-To:References:MIME-Version: Content-Transfer-Encoding; bh=RhdWlyO5Sam//srEVeWFrjzifW9W6rttgI3RE0aHgEU=; b=0f0qQcImbPXk45mBsYvTTebA6Od6E1pr4gA+ciWBgejgUeUs8swqb6YNJ1qFDmpawAHi fdMN3UrGksEuFqR8KPf+XRwJ+EWfjd0iPU0PTSBKNZ6ixWHpWSQiFywTMI/NiKkDt/Z6K 6QBv9DkksX6lGCh2d3gBPDbOr32uY+GPZnp3p9iuwa45CnKn4Fm67sj7MJi4gEinsymTC rFDoRXBuNFkwKnNxkib9UNJbmLeLj4NLJ6BGxPvPmxzJ25rN54dlniC/NLiI7nXdVSojj BPRh+ifFwGy18m/0l4yC9X82/f23CPwpYRZpC5pNVk9XWr7PWzlkySaCRhXGXb/aEag== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256 header.s=20260707 header.b=Gxp8WN3F; arc=none smtp.remote-ip=74.125.82.169 Received: from mail-dy1-f169.google.com (mail-dy1-f169.google.com [74.125.82.169]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0BFF0606A31A for ; Wed, 28 Oct 2026 05:41:52 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 0BFF0606A31A Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256 header.s=20260707 header.b=Gxp8WN3F Received: by mail-dy1-f169.google.com with SMTP id 5a478bee46e88-3645f0f3fcdso1059933eec.0 for ; Tue, 27 Oct 2026 22:41:52 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20260707; t=1793166112; x=1793770912; darn=lists.linux.dev; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to:content-type; bh=RhdWlyO5Sam//srEVeWFrjzifW9W6rttgI3RE0aHgEU=; b=Gxp8WN3FJSiKo4NKeQPC25Xr1vZZfBGwnBwyWHXlmq4aXzLCXodUynXZ2M8a3Mkdzr ggXgPywY6s+XetqlHONgDEAMLVboqdA/+sNqXzxs1WN+Xs/oldUufgKC94cym/2QSy0a 41U3XFox1AirWtNN/TSqbXYenf8X0/4+ocPoi9ppBT9jS7PBUkcjhGGwOf/6st9FdjgT w2eppFRrLDShQRDkecXrc1XDdvNnU+9MkikXRG7EY4crfCEAbtJ/0/f1NgVyrbVv3Hw2 JwSI6bFuf5IH2+THgNGokzR2VU/az+xWQr6Rp7Dfnb86Acyalp3gFLI8xUV+HhVK/o9q sFnA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20260707; t=1793166112; x=1793770912; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-gg:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to:content-type; bh=RhdWlyO5Sam//srEVeWFrjzifW9W6rttgI3RE0aHgEU=; b=vzHZegspfRsaIWd0yPLGyFszDVI/Ho8FKH9rxG7dgOqmNBR5XYaxzXVjXeTCIUYZ6b exE8dqNbwibn92vMfPwOjZvSDf0C1+541FJskqu3ox6AD1pZkAZ2LNN5fPgGgHMqQbkf b+15v09EsjwKfQ/1z52uaAeltMd7sw70rhjNoXDCTqO/aqABEavMQOi40Lvs/7n/6trh 0QrL3AQnzlfwJxNzYGC76V4CaYMBdjcpHJi3uaOYbVBG3HTY5eIv9PStWXHjsnfk1+EV rt4Ri5XyusRGJMP+U/aVj6UHD1FH5RfTGAtn+OEJWUkEut5dKr18+1vwOFcZolyv1ksL iMJQ== X-Gm-Message-State: AFq9FYJanViu4+utXeFOz/qcB3ZJaPJs3AVmma5qkDdOuct7xYuABakP p1sn9zX2HE354H1g7Uoj9nzSPjTSyIuDHbIzN6F8OilQ82xqNSD4HXwbUKQAgA== X-Gm-Gg: AYBFou2esvoZEJzODcrxQzLqT78WzGu7rK00SqC0QhZA/BgCBUvzkenG4t0k12uH/0i fizIrbCQ66bAUUyZ1Pl3TeUcBcD7n4RtKrdVWyE2kMkfLkF6MwXGE+N+PTTIavITd0RL4ZwyDzz A9T8yhnrJPQIVfdDOvcJWSBvt0W29Aqviu97s4SMZMg6bAjZqo8X7tvenaE1PuAcSer/5bKsV3R m7aun3rVdBlP409O8ETzf2FSxsmy/LQ/8Wa/PJ/AAos+8pRRNlROEbuPUM0SKNiSO8/z/7yP1+K CP3z/J54rYOdv4Py9PtxuYhjcsbY3jhhKx2VE0TRQqc3JxXcpWR5bGyFfvshUawgkKegEP13QVe aFq8nse7aRd2yf/orWoRIOCMLEcgVtf0QNiV2xWmSpt0UzOGAI0JigyFCCp+ueRIO3yr4M2/I9F 7pJBh/EVbWKFE7hqYMk0csKpMBcE+XXb0H9sZtsUjemOgrLGsQjm2duu+wI7xUC83Da6vMy6bjJ 1m+NkfTilSau4WO2+TqkWFq6xSOSuFWVZT957hNWheRD4+9EAl8ktGJ9NWxJAGVfYi+ru0XL1Qt ZdnMqc2zF0cjiLR9v7k6RAz7zrWKdCtA8Kt0e5KBT1oaBEW0wSeE7xC0E5PHMFApXBaMq27RVMB cizlCnPJxAjlIqpk0Aktobjqfa0zmGO2V0MrKN7/WCQ1CQ2uo/TRV6CcX/4vPLEax3Id29/SevA 8= X-Received: by 2002:a05:7301:2411:b0:369:fdae:c9fd with SMTP id 5a478bee46e88-36a201132b1mr2144488eec.13.1793166111791; Tue, 27 Oct 2026 22:41:51 -0700 (PDT) Received: from ramen-dev-security-2.asia-south1-c.c.ramen-dev-345017.internal (90.156.200.35.bc.googleusercontent.com. [35.200.156.90]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-36a237be80csm5860973eec.2.2026.10.27.22.41.50 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 27 Oct 2026 22:41:51 -0700 (PDT) From: Anil Kaushik To: mptcp@lists.linux.dev Cc: Anil Kaushik Subject: [PATCH mptcp-next v12 2/6] netlink: specs: mptcp: add the subflow-retries attribute Date: Wed, 28 Oct 2026 05:41:39 +0000 Message-Id: <20261028054143.3222998-3-anilkaushikwireless@gmail.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20261028054143.3222998-1-anilkaushikwireless@gmail.com> References: <20261028054143.3222998-1-anilkaushikwireless@gmail.com> X-Mailing-List: mptcp@lists.linux.dev List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" It will be used by the in-kernel PM to set the number of SYN retransmissions of a subflow re-created after a timeout, with the other limits: add it to the set-limits and get-limits commands. The uapi header and the generated files are updated with ynl-regen. Signed-off-by: Anil Kaushik --- Notes: v9: - after a timeout, not any error, and about 4 hours with the default RTO settings v8: - the default is the maximum, MAX_TCP_SYNCNT (127) (Matthieu) v7: - the doc gives the default value (netdev Sashiko) v6 (netdev Sashiko): - the policy checks the maximum value, 127 (MAX_TCP_SYNCNT) - the doc says the value works like TCP_SYNCNT v5: - new, split from the retry patch (Matthieu) Documentation/netlink/specs/mptcp_pm.yaml | 13 +++++++++++++ include/uapi/linux/mptcp_pm.h | 1 + net/mptcp/mptcp_pm_gen.c | 10 ++++++---- net/mptcp/mptcp_pm_gen.h | 4 ++-- 4 files changed, 22 insertions(+), 6 deletions(-) diff --git a/Documentation/netlink/specs/mptcp_pm.yaml b/Documentation/netl= ink/specs/mptcp_pm.yaml index 39f3facc38e5..690d3c5dfdd2 100644 --- a/Documentation/netlink/specs/mptcp_pm.yaml +++ b/Documentation/netlink/specs/mptcp_pm.yaml @@ -196,6 +196,16 @@ attribute-sets: name: addr-remote type: nest nested-attributes: address + - + name: subflow-retries + type: u32 + checks: + max: 127 + doc: | + SYN retries of a subflow re-created after a timeout, like the + TCP_SYNCNT socket option, so with tcp_syn_linear_timeouts on top. + The default is the maximum, MAX_TCP_SYNCNT (127), about 4 hours + with the default RTO settings. 0 to not re-create it. - name: event-attr enum-name: mptcp-event-attr @@ -327,6 +337,7 @@ operations: attributes: - rcv-add-addrs - subflows + - subflow-retries - name: get-limits doc: Get protocol limits @@ -337,10 +348,12 @@ operations: attributes: - rcv-add-addrs - subflows + - subflow-retries reply: attributes: - rcv-add-addrs - subflows + - subflow-retries - name: set-flags doc: Change endpoint flags diff --git a/include/uapi/linux/mptcp_pm.h b/include/uapi/linux/mptcp_pm.h index fe9863d75350..43e9643deda9 100644 --- a/include/uapi/linux/mptcp_pm.h +++ b/include/uapi/linux/mptcp_pm.h @@ -102,6 +102,7 @@ enum { MPTCP_PM_ATTR_TOKEN, MPTCP_PM_ATTR_LOC_ID, MPTCP_PM_ATTR_ADDR_REMOTE, + MPTCP_PM_ATTR_SUBFLOW_RETRIES, =20 __MPTCP_ATTR_AFTER_LAST }; diff --git a/net/mptcp/mptcp_pm_gen.c b/net/mptcp/mptcp_pm_gen.c index c180930a8e0e..e2d4af1bc1d5 100644 --- a/net/mptcp/mptcp_pm_gen.c +++ b/net/mptcp/mptcp_pm_gen.c @@ -44,15 +44,17 @@ const struct nla_policy mptcp_pm_flush_addrs_nl_policy[= MPTCP_PM_ENDPOINT_ADDR + }; =20 /* MPTCP_PM_CMD_SET_LIMITS - do */ -const struct nla_policy mptcp_pm_set_limits_nl_policy[MPTCP_PM_ATTR_SUBFLO= WS + 1] =3D { +const struct nla_policy mptcp_pm_set_limits_nl_policy[MPTCP_PM_ATTR_SUBFLO= W_RETRIES + 1] =3D { [MPTCP_PM_ATTR_RCV_ADD_ADDRS] =3D { .type =3D NLA_U32, }, [MPTCP_PM_ATTR_SUBFLOWS] =3D { .type =3D NLA_U32, }, + [MPTCP_PM_ATTR_SUBFLOW_RETRIES] =3D NLA_POLICY_MAX(NLA_U32, 127), }; =20 /* MPTCP_PM_CMD_GET_LIMITS - do */ -const struct nla_policy mptcp_pm_get_limits_nl_policy[MPTCP_PM_ATTR_SUBFLO= WS + 1] =3D { +const struct nla_policy mptcp_pm_get_limits_nl_policy[MPTCP_PM_ATTR_SUBFLO= W_RETRIES + 1] =3D { [MPTCP_PM_ATTR_RCV_ADD_ADDRS] =3D { .type =3D NLA_U32, }, [MPTCP_PM_ATTR_SUBFLOWS] =3D { .type =3D NLA_U32, }, + [MPTCP_PM_ATTR_SUBFLOW_RETRIES] =3D NLA_POLICY_MAX(NLA_U32, 127), }; =20 /* MPTCP_PM_CMD_SET_FLAGS - do */ @@ -127,7 +129,7 @@ const struct genl_ops mptcp_pm_nl_ops[11] =3D { .validate =3D GENL_DONT_VALIDATE_STRICT, .doit =3D mptcp_pm_nl_set_limits_doit, .policy =3D mptcp_pm_set_limits_nl_policy, - .maxattr =3D MPTCP_PM_ATTR_SUBFLOWS, + .maxattr =3D MPTCP_PM_ATTR_SUBFLOW_RETRIES, .flags =3D GENL_UNS_ADMIN_PERM, }, { @@ -135,7 +137,7 @@ const struct genl_ops mptcp_pm_nl_ops[11] =3D { .validate =3D GENL_DONT_VALIDATE_STRICT, .doit =3D mptcp_pm_nl_get_limits_doit, .policy =3D mptcp_pm_get_limits_nl_policy, - .maxattr =3D MPTCP_PM_ATTR_SUBFLOWS, + .maxattr =3D MPTCP_PM_ATTR_SUBFLOW_RETRIES, }, { .cmd =3D MPTCP_PM_CMD_SET_FLAGS, diff --git a/net/mptcp/mptcp_pm_gen.h b/net/mptcp/mptcp_pm_gen.h index b9280bcb43f5..5b4dee8a0a34 100644 --- a/net/mptcp/mptcp_pm_gen.h +++ b/net/mptcp/mptcp_pm_gen.h @@ -23,9 +23,9 @@ extern const struct nla_policy mptcp_pm_get_addr_nl_polic= y[MPTCP_PM_ATTR_TOKEN + =20 extern const struct nla_policy mptcp_pm_flush_addrs_nl_policy[MPTCP_PM_END= POINT_ADDR + 1]; =20 -extern const struct nla_policy mptcp_pm_set_limits_nl_policy[MPTCP_PM_ATTR= _SUBFLOWS + 1]; +extern const struct nla_policy mptcp_pm_set_limits_nl_policy[MPTCP_PM_ATTR= _SUBFLOW_RETRIES + 1]; =20 -extern const struct nla_policy mptcp_pm_get_limits_nl_policy[MPTCP_PM_ATTR= _SUBFLOWS + 1]; +extern const struct nla_policy mptcp_pm_get_limits_nl_policy[MPTCP_PM_ATTR= _SUBFLOW_RETRIES + 1]; =20 extern const struct nla_policy mptcp_pm_set_flags_nl_policy[MPTCP_PM_ATTR_= ADDR_REMOTE + 1]; =20 --=20 2.25.1 From nobody Thu Nov 5 07:28:49 2026 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=74.125.82.176 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793166115; b=dZG/obfi0wDKeIx7DiAcfd0n7d8JaJStFArVsFhGfMIXEf5K9NV+vUJONR0gobDz4FTD 3XAoq0H6GDr5+mOlZKx2pT5lk4CSbBUf9HBlL27zcTnimujt2Nih0STlUDArLh288uT5I 9XppmnJ1Onga9mtWC1VdT+Tz9mhIj1jxaLziKrjhkHUF315AI8qpKLEjbCQhqjAcyxxpw zU51siC/CnfxFk573LTaF4x06OnZEFS3zdJQtkOM4Fy9iytbw4PGsMSUlBhLdhLg1Egwn owHzQMp4A3FB7MMORV/pNBUc9YPH7JlZpSz6lb0LRU76NZ+PvwqTdNCvpBBTqbotZNA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793166115; h=DMARC-Filter:Received:DKIM-Signature:X-Google-DKIM-Signature: X-Gm-Message-State:X-Gm-Gg:X-Received:Received:From:To:Cc:Subject: Date:Message-Id:X-Mailer:In-Reply-To:References:MIME-Version: Content-Transfer-Encoding; bh=GMa51ST4XjCQkd4qYSnBFNlKaUJYxzH2Que0Zxlz+Ok=; b=s6pCOofxLaOB2mldCVcb6sCslXITUxvmHWdBRMn/nuG/3itTDQXVs6bBem7ISbiBxOQi kGZDJE1ojTlaBSZNS7CEEqe71w4aFtuJenn00TdRGWiYVXUYSPAvEp36MU+pIyQe91GRs f7r3yJbKPIQWo5XMKkdWv5Myzsem/7rLqI0RpI4m9zs8smFKnItIcEsaPq9UhotTqTBK0 U7yS43ITzN+AVf5oOL6GMnceKv+218vX8s5+eJX+v2l5fu5N6P+1y2R/Vr1UXjxhtrD2I gjlk2ZhXEjxV8q/Hj9XJu6/BanyYLnKaBSXM42Tq4NY0BNJKyKWKtBNl+fU2fjnBUjw== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256 header.s=20260707 header.b=OHHPOaif; arc=none smtp.remote-ip=74.125.82.176 Received: from mail-dy1-f176.google.com (mail-dy1-f176.google.com [74.125.82.176]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id EAC8C606A31A for ; Wed, 28 Oct 2026 05:41:54 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org EAC8C606A31A Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256 header.s=20260707 header.b=OHHPOaif Received: by mail-dy1-f176.google.com with SMTP id 5a478bee46e88-33fb4680717so1332651eec.1 for ; Tue, 27 Oct 2026 22:41:54 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20260707; t=1793166114; x=1793770914; darn=lists.linux.dev; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to:content-type; bh=GMa51ST4XjCQkd4qYSnBFNlKaUJYxzH2Que0Zxlz+Ok=; b=OHHPOaiftJl8sJAgbioga/eSufDEooLY3tfPiJdoxcikeBAuz+w3mZ7MYTg9TfdSL2 349lfvRUlxjranUQ0lmDdfsrXhLBaBpbZ7Tg1LxeOgCGuuzakgix/vvLm5BIHf60ptiN IQTrz5dVDjcWEKwdLA/u+75+a2Et9HBbRX6XJgcJNmKq5f/IZzsOBdVw5Dos/dj1WhA1 6DJQNYb0opcCn6P0CKylGpKJfsZue6jOQQLw5CrVZg5R+6qzsigX11wLk57QBMNGRn+J fNeRzekovSjre5NG2Q8PxOlikuNwQUiZxdw3AKsLaOSj5yNS4clQkNpKeoNDm7i4IiJF 4HEQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20260707; t=1793166114; x=1793770914; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-gg:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to:content-type; bh=GMa51ST4XjCQkd4qYSnBFNlKaUJYxzH2Que0Zxlz+Ok=; b=fCTQPZTOVPV74NAymNznfFjgSAV8TC1fqmPeQmAbwnrVqi+s5kMdgia0SMXom6tDGP Oayo/OUz9wVj3KQJe85mN+R9s1inUDJt+emt55i2243u9CLOMAp2fTKDM9FFcv3vobra Cm78JgDbmww3U9Wjlq7xqWNuN+ir84bDKYjNlDJTdp5VAdqPy6J8r4NLhUOks5O152kN WCnP82p/Es3OVNIQX629oprUvPwStYGWwAlNuAgMN2+ZoXXdi7TCB74ZfOOuY1MRNJOV BOXGCbnshtEovaCtOw2z7+RrfstfR1nURxoJB5KaIU9Z7KSxBHZP0e7SzwflcooZjyH8 JMLA== X-Gm-Message-State: AFq9FYJ6ZpUjHNpLs69hRSy4qYqmtCcgBnEpNwlG8KN0Zpi8HniJ/xxm SM5uAKpVHfRuZO8gElMRpHBcmWW0Wwzl+ECXLAH1QOU+2F/RSmJB7bLDFwoRjQ== X-Gm-Gg: AYBFou0J5+dAXXTNDseeKMBWLmI172kzxvKSy6IUSrw/ZW5wYfbpfwXBXkIkIP6KOvr o0qKRIeyuFRX4QeEQH1bkSXN+Kzhg5ek72wJ1xTVjsF5ewd6eORtsnXitXS5J7Emh4sAgWJbgwJ xBrHcNmJC5XfLxvSwTO/1y5Zv4LIVVytbC12vhMQ6uUoyE3k231F5a4uIg6DuRqOvzZW7+n8Bvv lpfNDgf2DhE1UvynfMUpAwidNrqPBuRcJoAPdxonT5+FnNDAjukdcj/bWBjyrvfegGk1nj8cHfZ RPCuQi/93vrEOd11X3R0WXOBPA6BpWV9DtONStPQcaGVd88O/BdldN98e95a2b/C5/EgZ9zjg/2 vjwrVnqqMh7WWC6WJ0Skv+p6tXrzp0X9oL5z4BTxI0/zZG61lDxVO048GNZSjVXGFSGoe83wVwF Q0hQrfEI6yXgDfgRbylCfeyA39VQwn7DtRtB1y81BVUwSx2cSCfBjOzzMZKlJyiVKsCODp+TTck qniDhBpVfufnEeMXWY97+FEYREO3C5HfCRpc485YArx1wMR82EQ/Bk6tqH+cNRF2MJNI6+iOaPD w+QG4RWqC3j139yyTOt5Q8Q4DUHG4jw8vL3IaFWjTbiWLHO7EPzoShw83nTRmeCwTYje4C3msM8 LGgopqKN+i/HEAF2J+bGwHt71b1tMG9U1aTCFyBJoYSJQ5ypRPVNJ8GeNpccyIhiAAKMIP2hrlQ == X-Received: by 2002:a05:7301:180c:b0:369:f2f4:b227 with SMTP id 5a478bee46e88-36a203e4a69mr2244164eec.18.1793166113830; Tue, 27 Oct 2026 22:41:53 -0700 (PDT) Received: from ramen-dev-security-2.asia-south1-c.c.ramen-dev-345017.internal (90.156.200.35.bc.googleusercontent.com. [35.200.156.90]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-36a237be80csm5860973eec.2.2026.10.27.22.41.52 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 27 Oct 2026 22:41:53 -0700 (PDT) From: Anil Kaushik To: mptcp@lists.linux.dev Cc: Anil Kaushik Subject: [PATCH mptcp-next v12 3/6] mptcp: pm: in-kernel: add the subflow-retries limit Date: Wed, 28 Oct 2026 05:41:40 +0000 Message-Id: <20261028054143.3222998-4-anilkaushikwireless@gmail.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20261028054143.3222998-1-anilkaushikwireless@gmail.com> References: <20261028054143.3222998-1-anilkaushikwireless@gmail.com> X-Mailing-List: mptcp@lists.linux.dev List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" A new limit for the in-kernel PM, set and read with the other limits: the number of SYN retries of a subflow re-created after a timeout, like the TCP_SYNCNT socket option. The default is the maximum, MAX_TCP_SYNCNT (127), about 4 hours, and 0 to not re-create it. The netlink policy checks this maximum value. It is also exposed in struct mptcp_info, in place of the reserved field. The next patch uses it. Signed-off-by: Anil Kaushik --- Notes: v9: - MAX_TCP_SYNCNT instead of 127 for the default - after a timeout, not any error v8: - the default is the maximum, 127, about 4 hours (Matthieu) v6: - the netlink policy checks the maximum, no more parse_limit() change (netdev Sashiko) - the limit works like TCP_SYNCNT, say so (netdev Sashiko) v5: - new, split from the retry patch (Matthieu) - the limit is also in struct mptcp_info (Matthieu) include/uapi/linux/mptcp.h | 2 +- net/mptcp/pm_kernel.c | 23 ++++++++++++++++++++++- net/mptcp/protocol.h | 1 + net/mptcp/sockopt.c | 2 ++ 4 files changed, 26 insertions(+), 2 deletions(-) diff --git a/include/uapi/linux/mptcp.h b/include/uapi/linux/mptcp.h index 72a5d030154e..d7e3f359773d 100644 --- a/include/uapi/linux/mptcp.h +++ b/include/uapi/linux/mptcp.h @@ -72,7 +72,7 @@ struct mptcp_info { __u8 mptcpi_subflows_total; __u8 mptcpi_endp_laminar_max; __u8 mptcpi_endp_fullmesh_max; - __u8 reserved; + __u8 mptcpi_limit_subflow_retries; __u32 mptcpi_last_data_sent; __u32 mptcpi_last_data_recv; __u32 mptcpi_last_ack_recv; diff --git a/net/mptcp/pm_kernel.c b/net/mptcp/pm_kernel.c index d3014bf57bf3..7fb4c7874340 100644 --- a/net/mptcp/pm_kernel.c +++ b/net/mptcp/pm_kernel.c @@ -25,6 +25,7 @@ struct pm_nl_pernet { u8 endp_fullmesh_max; u8 limit_add_addr_accepted; u8 limit_extra_subflows; + u8 limit_subflow_retries; u8 next_id; DECLARE_BITMAP(id_bitmap, MPTCP_PM_MAX_ADDR_ID + 1); }; @@ -96,6 +97,14 @@ u8 mptcp_pm_get_limit_extra_subflows(const struct mptcp_= sock *msk) } EXPORT_SYMBOL_GPL(mptcp_pm_get_limit_extra_subflows); =20 +u8 mptcp_pm_get_limit_subflow_retries(const struct mptcp_sock *msk) +{ + struct pm_nl_pernet *pernet =3D pm_nl_get_pernet_from_msk(msk); + + return READ_ONCE(pernet->limit_subflow_retries); +} +EXPORT_SYMBOL_GPL(mptcp_pm_get_limit_subflow_retries); + static bool has_subflow_daddr(const struct mptcp_sock *msk, const struct mptcp_addr_info *daddr) { @@ -1419,7 +1428,8 @@ static int parse_limit(struct genl_info *info, int id= , unsigned int *limit) int mptcp_pm_nl_set_limits_doit(struct sk_buff *skb, struct genl_info *inf= o) { struct pm_nl_pernet *pernet =3D genl_info_pm_nl(info); - unsigned int rcv_addrs, subflows; + unsigned int rcv_addrs, subflows, retries; + struct nlattr *attr; int ret; =20 spin_lock_bh(&pernet->lock); @@ -1433,8 +1443,13 @@ int mptcp_pm_nl_set_limits_doit(struct sk_buff *skb,= struct genl_info *info) if (ret) goto unlock; =20 + /* the maximum, MAX_TCP_SYNCNT, is checked by the policy */ + attr =3D info->attrs[MPTCP_PM_ATTR_SUBFLOW_RETRIES]; + retries =3D nla_get_u32_default(attr, pernet->limit_subflow_retries); + WRITE_ONCE(pernet->limit_add_addr_accepted, rcv_addrs); WRITE_ONCE(pernet->limit_extra_subflows, subflows); + WRITE_ONCE(pernet->limit_subflow_retries, retries); =20 unlock: spin_unlock_bh(&pernet->lock); @@ -1464,6 +1479,10 @@ int mptcp_pm_nl_get_limits_doit(struct sk_buff *skb,= struct genl_info *info) READ_ONCE(pernet->limit_extra_subflows))) goto fail; =20 + if (nla_put_u32(msg, MPTCP_PM_ATTR_SUBFLOW_RETRIES, + READ_ONCE(pernet->limit_subflow_retries))) + goto fail; + genlmsg_end(msg, reply); return genlmsg_reply(msg, info); =20 @@ -1618,6 +1637,8 @@ static int __net_init pm_nl_init_net(struct net *net) =20 /* Cit. 2 subflows ought to be enough for anybody. */ pernet->limit_extra_subflows =3D 2; + /* the maximum: about 4 hours with the default RTOs */ + pernet->limit_subflow_retries =3D MAX_TCP_SYNCNT; pernet->next_id =3D 1; spin_lock_init(&pernet->lock); =20 diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h index 3be60da12924..4aa4aedb2ba7 100644 --- a/net/mptcp/protocol.h +++ b/net/mptcp/protocol.h @@ -1266,6 +1266,7 @@ u8 mptcp_pm_get_endp_laminar_max(const struct mptcp_s= ock *msk); u8 mptcp_pm_get_endp_fullmesh_max(const struct mptcp_sock *msk); u8 mptcp_pm_get_limit_add_addr_accepted(const struct mptcp_sock *msk); u8 mptcp_pm_get_limit_extra_subflows(const struct mptcp_sock *msk); +u8 mptcp_pm_get_limit_subflow_retries(const struct mptcp_sock *msk); =20 /* called under PM lock */ static inline void __mptcp_pm_close_subflow(struct mptcp_sock *msk) diff --git a/net/mptcp/sockopt.c b/net/mptcp/sockopt.c index 922f6ae5c80c..d3c4abf59ec5 100644 --- a/net/mptcp/sockopt.c +++ b/net/mptcp/sockopt.c @@ -1075,6 +1075,8 @@ void mptcp_diag_fill_info(struct mptcp_sock *msk, str= uct mptcp_info *info) mptcp_pm_get_endp_laminar_max(msk); info->mptcpi_endp_fullmesh_max =3D mptcp_pm_get_endp_fullmesh_max(msk); + info->mptcpi_limit_subflow_retries =3D + mptcp_pm_get_limit_subflow_retries(msk); } =20 if (__mptcp_check_fallback(msk)) --=20 2.25.1 From nobody Thu Nov 5 07:28:49 2026 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=74.125.82.171 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793166117; b=rd1cBbOuxze9AzOVOJ+cO5jtHT5bOP8Sc9fEancF04hKRwl5cF0ilt+jt2bIvGmyhUDt lHvSdjG7+nYME9WLdOOLa5I007zYjYuQav0p851vEDy9NDeFYm5igg0XXgV9RHc0uHuI+ /UqBQDf/+pO67bsPtFy6eghWkaNpJj96d+CsX/w3dchXuhx8DzAmyj3eg/EbGsQsHqZb1 5m046714gPTZp/Na3NLjQBL7gNwynzy05EytueayH8VCUpwTzn/6Y0AzJSewwnIHna0pa ooFBCkaREzpprS3nYxc0CMpeyiN8ERpmVoPy/V6X1mDErIpMU2RtDZgk26k+9/M7nSQ== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793166117; h=DMARC-Filter:Received:DKIM-Signature:X-Google-DKIM-Signature: X-Gm-Message-State:X-Gm-Gg:X-Received:Received:From:To:Cc:Subject: Date:Message-Id:X-Mailer:In-Reply-To:References:MIME-Version: Content-Transfer-Encoding; bh=qmDxTlzsY8yvstXvG0/Q4jEjeXBbLmpfftJrWvqDJ0k=; b=0s4hfUEtaItst0YpZ4kzESJfeboVYSv/bKMVhMoz3vReDAiejLTlZouxjQeTP5pvwohV yOXB8M0AnCsgeBj8g/0JaHMEHhxnopEhzO/dWJRC/gkHsMOqW58fIBzDqPOnrQtSmQSdv VQZF0p3K44LSduMQv2tYp6dqlhNmpETWtYZaDO9gBdqdOLvrbXvUtl/seKUv3mOClDdm7 b2ix9ueNCWzgp2PEFUfdPYaV56rnpfKNpSFsvt6OZz+xt+usMypqOxLRdETIpqqbIJgxi 03mIvKVVtcapzenBXDtlUOuXlEQ5SKRRieZiaCqvbI0oodlSmAqxdaFs1LXYxBfGz1Q== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256 header.s=20260707 header.b="s/So5qh5"; arc=none smtp.remote-ip=74.125.82.171 Received: from mail-dy1-f171.google.com (mail-dy1-f171.google.com [74.125.82.171]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1E35E606A31A for ; Wed, 28 Oct 2026 05:41:56 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 1E35E606A31A Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256 header.s=20260707 header.b=s/So5qh5 Received: by mail-dy1-f171.google.com with SMTP id 5a478bee46e88-36661f953e4so985873eec.1 for ; Tue, 27 Oct 2026 22:41:56 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20260707; t=1793166116; x=1793770916; darn=lists.linux.dev; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to:content-type; bh=qmDxTlzsY8yvstXvG0/Q4jEjeXBbLmpfftJrWvqDJ0k=; b=s/So5qh5LB9tr/invG0TFl9EXUJog35c/Lt5VsXvTnfBsTMLSoZSSaYXSZsgXR61HO g2hggAn+XU4e1Y4NlSFx0xCOEaoHcxYGlxi9FDPyizMp67uTv8Ww2Y/oz1GsPUA0KXQ9 wzCTNVMOiiHmpgiP6RCQB0oKPxdWyg+Bkk+koMgssGjGZbL5W5+W6aa6oI+rXR5f3fRW JVVqUl7hRUQqNatTdXM/EHfbOhlYd1dHL8iy0vM8+2MwG6Dy1CMZ8SoBpFVd8SWGYf/F /++nw1WnfXkVpEhVrJB9Z8o3jo1L3XA60dUtd8f7V/h0iVEBO1F/Apd0Tm9Vi148J0HI M9bA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20260707; t=1793166116; x=1793770916; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-gg:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to:content-type; bh=qmDxTlzsY8yvstXvG0/Q4jEjeXBbLmpfftJrWvqDJ0k=; b=AXHqAJSOW9G8VncVUKjy+nYb/u2fp0pe/Jwar03bEM6XyqKBhgAwGr8JfjYyo24stK YeL35zqn4dZpTPmq6xN6Lm7V9uvho/GmMTkXS8MCxbJCVMIhXBppxpWaCtE61Txx73VN YHCKduWvdf5AzIQoMab/4L6xS5qF9FfVYGkZ51vaLXk87CLvB0xalXLT99pxsYeTUxwC GrQFf2TDU+5EbnNzTQBAjr1vBXj1T+BmZyhvQfzLll7NjRqRgwO7HZPhhCkhecej1GzE w0VOjci1uZfJXFwV2ZANLQyX4TDaxwHECmF5hnQ3U7vDaOaWprlXdtScmZ8kH9zokpp2 YJuQ== X-Gm-Message-State: AFq9FYJ/ACAYcRE3os5AdMtiBj2/LmCTZTkSWNQ/lQV7SX6UYNsjdHW8 0HAIoSod/61Xe0NqOP43pIYVj3wFjU1IJ4oOnn4FhGFzm3eyKPZQrZAdRycRXg== X-Gm-Gg: AYBFou161Nl8e4DbU4X9buV4eTDMqh00mw+gqaWuymvaNkzZP1KFan42hXzj8b6ZdUO Gh2Pfkxh/+qDbRTnUSJevSysbGF+7L1d406AMTrQXjeZxvBxzRpr3pDLHOuQD62Ao6rvk9TsTiD zYAVYVl+0XY8NhWHrBBbpkxUlXJMGd0oFc5KpszYDg0ZGQ8rfAEDIPb7Lm+vAYRWzAM+SpiIs8i D9d/2S5UQaADO8Rxr3LMpQBlCQ23sw7LalydNKv1YWeil2SV+MqFlzdzcVpsHAOePfR0286WU3y d45+90vWL3v0C/zdxc5mL11T1vzxOB+h3nPvRw7BHbqk1uVO8TjT2/8LkgVXPOKVYwnMgj9HRAm FIOmgwsiep6OUcfzGsPPrknIe5bokWNYwsP6gdkfEMoCio+oay35ZQggW9j1Zg6vCSSIGMnqxy+ wsz3bGKsb/Gpm5vl22V3k69hg9R6CTlXEGOFvFMUYdyL7PjTe3KdOecwobp/8UhKv9I2Lz24D4N lPK8wBNtcEFMu0CKnYTkE4Ye7Wdwcaey+JEWEVWp6TMA9heMRsil1O9OaDPFqgyVngYvUzSCerW L7yG8AiriZYdEpEur0nLdjCML+ditXiVEfdNbzFrkjtmAYmJqmM1Zxd12HsyB9fBUIYHXfoZu+u E81y7SgvQW0mXO3YeYDQnOZjBWxBERc4jLAYbNMd3Ja2aKTZxSc1sh7wdNCCjX1s6wqxzJJEZiA == X-Received: by 2002:a05:7301:1925:b0:351:68e8:4646 with SMTP id 5a478bee46e88-36a20469b48mr2903476eec.37.1793166115777; Tue, 27 Oct 2026 22:41:55 -0700 (PDT) Received: from ramen-dev-security-2.asia-south1-c.c.ramen-dev-345017.internal (90.156.200.35.bc.googleusercontent.com. [35.200.156.90]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-36a237be80csm5860973eec.2.2026.10.27.22.41.54 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 27 Oct 2026 22:41:55 -0700 (PDT) From: Anil Kaushik To: mptcp@lists.linux.dev Cc: Anil Kaushik Subject: [PATCH mptcp-next v12 4/6] mptcp: pm: in-kernel: retry subflows closed after an error Date: Wed, 28 Oct 2026 05:41:41 +0000 Message-Id: <20261028054143.3222998-5-anilkaushikwireless@gmail.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20261028054143.3222998-1-anilkaushikwireless@gmail.com> References: <20261028054143.3222998-1-anilkaushikwireless@gmail.com> X-Mailing-List: mptcp@lists.linux.dev List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" With the in-kernel PM, a subflow closed after an error, e.g. a timeout when a path silently drops packets, is never re-created, even once the path works again. For example, with a main link and a backup link, connections move to the backup after an outage but never come back. When TCP gives up on an established subflow created by this side, after a retransmission or keepalive timeout, whatever ICMP error was received from the path before, the PM now creates a new one with the same addresses. Its SYN retries, set like TCP_SYNCNT by the subflow-retries limit, space out the attempts. This is a single connection attempt: an ICMP error, or a local error when connecting, ends it, and it is not retried again. It is also closed if the MPTCP socket is closed in the meantime. This is only done while another subflow can send data: otherwise the connection is closed after the close timeout, as before. The re-created subflows still connecting are closed when no other subflow can send data anymore, and the ones not established yet when the MPTCP socket is shut down or closed. Once it is established, it is handled like any other subflow. Re-creating the initial subflow uses one of the additional subflows allowed by the limits. __mptcp_close_ssk() now always cleans the references to the closed subflow in the MPTCP backlog, not only with MPTCP_CF_PUSH: a re-created subflow closed with the MPTCP socket can get established in between. The other paths without MPTCP_CF_PUSH have already purged the backlog. A subflow reset by the peer, or by anything on the path, is not re-created: the path works, and re-creating it right away could loop. A subflow that never got established is not re-created either: the PM keeps trying the next endpoints, as before. Subflows aborted locally, also by MPTCP, or using an address that has been removed are not retried. TCP only closes a subflow after tcp_retries2 retransmissions, about 15 minutes by default. A subflow that only receives data never gets an error: the application has to enable TCP keepalive on the MPTCP socket, which MPTCP applies to all the subflows. Both are documented in mptcp.rst. Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/440 Signed-off-by: Anil Kaushik --- Notes: v12: - when no other subflow can send data, only close the re-created subflows still connecting: a joined one is fully established soon, and stop once one got established (netdev Sashiko) - a subflow in CLOSE_WAIT does not keep the re-created ones open either: one helper for both checks (netdev Sashiko) - mptcp.rst: the initial subflow is not re-created if the peer does not accept joins to its initial address (netdev Sashiko) v11: - re-create a subflow only while another subflow can send data: the close timeout is then handled as before, no more re-arming nor stopping it (sashiko.dev) - close the re-created subflows not established yet from the worker, or when the msk is shut down or closed, never while iterating on the subflows: mptcp_close_ssk() only schedules the worker (sashiko.dev) - also close them once the msk is no longer established, whatever their TCP state, also when a DATA_FIN is handled outside the worker (sashiko.dev) - SUB_CLOSED event for them while the msk is established, like mptcp_close_ssk(): they can have been joined already - another subflow in CLOSE_WAIT, being closed, does not count as one that can send data v10: - keep the connection when the close timeout expires if a re-created subflow connected in the meantime: an active join does not stop the timer, mptcp_finish_join() returns early for it (sashiko.dev) - close the re-created subflows still connecting once the msk is no longer established, after a DATA_FIN or a shutdown(), when no other subflow is left: they cannot join anymore, and would keep the msk around (sashiko.dev) v9: - every timeout is retried, whatever ICMP error TCP reports for it, the last one received, see tcp_write_err(): resets, local aborts and MPTCP protocol errors are excluded instead of listing the timeout errors, so IPv4 and IPv6 behave the same (netdev Sashiko) - mptcp.rst: 0 does not re-create the subflows (netdev Sashiko) - the re-created subflows closed with the msk get no SUB_CLOSED event, like the other subflows closed with it - if no other subflow can send data, the close timeout still applies: creating the new subflow no longer keeps the connection open for the whole SYN retries - doc and commit message: a single connection attempt, ended by an ICMP error or a local connect error - __mptcp_close_ssk() always cleans the msk backlog of the closed subflow: a re-created subflow closed with the msk can have been established in between, with data in the backlog (netdev Sashiko). It is still closed without MPTCP_CF_PUSH, which would re-send all the pending data - tcp_sock_set_syncnt(), without the ssk lock v8: - mptcp.rst gives the default, 127, about 4 hours - close the re-created subflows still connecting before __mptcp_wr_shutdown() disconnects them, and also the already disconnected ones, e.g. after shutdown(SHUT_WR) (sashiko.dev) - mptcp.rst: the initial subflow on the client side, the subflows limit, and only one attempt (netdev Sashiko) v7: - only after a path error, a retransmission or keepalive timeout: a reset from the peer or the path could make it loop (netdev Sashiko) - retry and no_retry are bools under the msk socket lock, in the padding after close_event_done, not bits next to the reset ones (netdev Sashiko) - mark all the subflows using a removed address, whatever their state (netdev Sashiko) - doc: tcp_retries2, and keepalive for a subflow that only receives data (Abdul Wasey's tests) - not retried after a reset by MPTCP itself, even with an old sk_err left by IP_RECVERR (netdev Sashiko) - close the re-created subflows still connecting without MPTCP_CF_PUSH: they never carried data (netdev Sashiko) v6 (netdev Sashiko): - only re-create subflows that were established: the PM still tries the next endpoints when one never gets established - only once TCP closed the subflow, to read its reset flags safely - removed addresses, also the remote ones and the local ID 0: the dead subflows are marked in mptcp_pm_rm_addr_or_subflow(), instead of looking up the endpoint v5 (Matthieu): - split in 4 patches - reverse xmas tree in mptcp_pm_kernel_retry_check() - "in-kernel" in the subject, like the other in-kernel PM patches - close the re-created subflows still connecting when the socket is closed (Matthieu: closing the socket during a retry) v4 (Matthieu): - netlink limit, on by default, instead of the sysctl - one new subflow per failure, its SYN retries set from the limit: no socket reuse, no attempts counter, no 60s check - no MIB counter - not retried if the endpoint was removed, instead of the pm.c change - called through pm.c - new bit in the subflow context, no new hole - commit message: MP_RST, not any RST (Sashiko) v3 (Sashiko): - no retry after MP_RST without the T flag, local abort or EBADMSG - no retry on a removed endpoint or address - use only request_bkup for the backup flag v2: - use the subflow sockets, no list or timer - code moved to pm_kernel.c Documentation/networking/mptcp.rst | 19 ++++ net/mptcp/pm.c | 39 ++++++++ net/mptcp/pm_kernel.c | 137 +++++++++++++++++++++++++++++ net/mptcp/protocol.c | 78 +++++++++++++++- net/mptcp/protocol.h | 50 +++++++++++ 5 files changed, 320 insertions(+), 3 deletions(-) diff --git a/Documentation/networking/mptcp.rst b/Documentation/networking/= mptcp.rst index b6753ffb9c9a..719f1fda3690 100644 --- a/Documentation/networking/mptcp.rst +++ b/Documentation/networking/mptcp.rst @@ -73,6 +73,25 @@ To be able to use multiple IP addresses on a host to cre= ate multiple *subflows* addresses can be used. This can be configured with ``ip mptcp endpoint`` f= or example. =20 +When TCP gives up on an established subflow created by this host, after a +retransmission or keepalive timeout, the in-kernel path manager creates it +again, with the ``subflow-retries`` limit as its number of SYN retries, li= ke +``TCP_SYNCNT``: 127 by default, about 4 hours, and 0 to not re-create it. = This +is done for the additional subflows, and for the initial one on the client= side: +the new subflow then takes one of the additional subflows allowed by the +``subflows`` limit. The initial one is not created again if the peer does = not +accept joins to its initial address. This is a single connection attempt: = an +ICMP error, or a local error when connecting, ends it, and it is not creat= ed +again. This is only done while another subflow can send data: otherwise the +connection is closed after ``close_timeout``, as before, and the subflows = being +re-created are closed too. A subflow reset by the peer, or by anything on = the +path, is not created again either. TCP only gives up on a subflow after +``tcp_retries2`` retransmissions, about 15 minutes by default: shorter out= ages +are handled by TCP itself. A subflow that only receives data does not noti= ce +that its path stopped working: the application should then enable TCP keep= alive +on the MPTCP socket (``SO_KEEPALIVE``, ``TCP_KEEPIDLE``, ``TCP_KEEPINTVL``= and +``TCP_KEEPCNT``), which MPTCP applies to all its subflows. + Packet Scheduler ---------------- =20 diff --git a/net/mptcp/pm.c b/net/mptcp/pm.c index d7c5b50b34cc..2bb08be95cd1 100644 --- a/net/mptcp/pm.c +++ b/net/mptcp/pm.c @@ -694,6 +694,26 @@ void mptcp_pm_subflow_check_next(struct mptcp_sock *ms= k, spin_unlock_bh(&pm->lock); } =20 +/* Called with the msk socket lock held, before closing a subflow: true if + * it has to be re-created once closed, see mptcp_pm_subflow_retry(). + */ +bool mptcp_pm_subflow_retry_check(struct mptcp_sock *msk, + const struct mptcp_subflow_context *subflow, + struct mptcp_pm_retry *retry) +{ + if (!mptcp_pm_is_kernel(msk)) + return false; + + return mptcp_pm_kernel_retry_check(msk, subflow, retry); +} + +void mptcp_pm_subflow_retry(struct mptcp_sock *msk, + const struct mptcp_pm_retry *retry) +{ + if (mptcp_pm_is_kernel(msk)) + mptcp_pm_kernel_retry(msk, retry); +} + void mptcp_pm_add_addr_received(const struct sock *ssk, const struct mptcp_addr_info *addr) { @@ -762,6 +782,24 @@ static void mptcp_pm_add_addr_send_ack(struct mptcp_so= ck *msk) mptcp_pm_schedule_work(msk, MPTCP_PM_ADD_ADDR_SEND_ACK); } =20 +/* A subflow using a removed address must not be re-created, whatever its + * state, e.g. closed by TCP but not collected yet, see + * mptcp_pm_kernel_retry_check(). + */ +static void mptcp_pm_rm_no_retry(struct mptcp_subflow_context *subflow, + enum linux_mptcp_mib_field rm_type, u8 rm_id) +{ + u8 id; + + if (rm_type =3D=3D MPTCP_MIB_RMADDR) + id =3D READ_ONCE(subflow->remote_id); + else + id =3D subflow_get_local_id(subflow); + + if (id =3D=3D rm_id) + subflow->no_retry =3D true; +} + static void mptcp_pm_rm_addr_or_subflow(struct mptcp_sock *msk, const struct mptcp_rm_list *rm_list, enum linux_mptcp_mib_field rm_type) @@ -794,6 +832,7 @@ static void mptcp_pm_rm_addr_or_subflow(struct mptcp_so= ck *msk, int how =3D RCV_SHUTDOWN | SEND_SHUTDOWN; u8 id =3D subflow_get_local_id(subflow); =20 + mptcp_pm_rm_no_retry(subflow, rm_type, rm_id); if ((1 << inet_sk_state_load(ssk)) & (TCPF_FIN_WAIT1 | TCPF_FIN_WAIT2 | TCPF_CLOSING | TCPF_CLOSE)) continue; diff --git a/net/mptcp/pm_kernel.c b/net/mptcp/pm_kernel.c index 7fb4c7874340..f06b24a9cd53 100644 --- a/net/mptcp/pm_kernel.c +++ b/net/mptcp/pm_kernel.c @@ -1610,6 +1610,143 @@ bool mptcp_pm_nl_check_work_pending(struct mptcp_so= ck *msk) return true; } =20 +/* TCP gave up on the path: after a retransmission, keepalive or user + * timeout, sk_err is ETIMEDOUT, or the last ICMP error received from the + * path, see tcp_write_err(). The other errors on an established subflow + * are not path failures: a reset, from the peer or from anything on the + * path (ECONNRESET, or EPIPE in CLOSE_WAIT, see tcp_reset()), a local + * abort (ECONNABORTED), or an MPTCP protocol error (EBADMSG). + */ +static bool mptcp_pm_retry_path_error(int err) +{ + switch (err) { + case ECONNRESET: + case EPIPE: + case ECONNABORTED: + case EBADMSG: + return false; + } + + return true; +} + +static bool mptcp_pm_retry_other_subflow(struct mptcp_sock *msk) +{ + struct mptcp_subflow_context *subflow; + + mptcp_for_each_subflow(msk, subflow) { + if (mptcp_subflow_can_send(subflow)) + return true; + } + + return false; +} + +/* Called with the msk socket lock held, before the subflow is closed */ +bool mptcp_pm_kernel_retry_check(struct mptcp_sock *msk, + const struct mptcp_subflow_context *subflow, + struct mptcp_pm_retry *retry) +{ + struct sock *ssk =3D mptcp_subflow_tcp_sock(subflow); + struct sock *sk =3D (struct sock *)msk; + int err; + + /* Only once TCP closed it: the acquire in inet_sk_state_load() makes + * sure sk_err and the resetting flag checked below are the ones of + * this close. + */ + if (inet_sk_state_load(ssk) !=3D TCP_CLOSE) + return false; + + err =3D READ_ONCE(ssk->sk_err); + retry->syn_retries =3D mptcp_pm_get_limit_subflow_retries(msk); + if (!retry->syn_retries || !err || sk->sk_state !=3D TCP_ESTABLISHED || + __mptcp_check_fallback(msk)) + return false; + + /* mptcp_close_ssk() will not handle it again, e.g. the initial + * subflow, kept in the list once closed + */ + if (subflow->close_event_done || READ_ONCE(subflow->local_id) < 0) + return false; + + /* Only a path that worked is tried again. If a subflow never got + * established, the PM moves on to the next endpoints instead, and a + * re-created subflow that cannot connect is not retried again: its SYN + * retransmissions already spaced out the tries. + */ + if (!READ_ONCE(subflow->fully_established)) + return false; + + /* its address has been removed, see mptcp_pm_rm_addr_or_subflow() */ + if (subflow->no_retry) + return false; + + /* Only while another subflow can send data: without one, the + * connection is closed after the close timeout, as before, see + * __mptcp_close_ssk(). + */ + if (!mptcp_pm_retry_other_subflow(msk)) + return false; + + /* Only when the path stopped working. A reset, from the peer or from + * anything on the path, means the path works: re-creating the subflow + * right away could loop. Not after a reset by MPTCP itself either, with + * mptcp_subflow_reset(), whatever sk_err says. + */ + if (!mptcp_pm_retry_path_error(err) || subflow->resetting) + return false; + + /* Only re-create subflows initiated by this side: MP_JOIN ones, or the + * initial one on the client side. + */ + if (!subflow->request_join && + (subflow->mp_join || READ_ONCE(msk->pm.server_side))) + return false; + + mptcp_remote_address((struct sock_common *)ssk, &retry->remote); + retry->remote.id =3D READ_ONCE(subflow->remote_id); + if (!retry->remote.id && READ_ONCE(msk->pm.remote_deny_join_id0)) + return false; + + mptcp_local_address((struct sock_common *)ssk, &retry->local.addr); + retry->local.addr.port =3D 0; + retry->local.addr.id =3D subflow_get_local_id(subflow); + retry->local.flags =3D subflow->request_bkup ? + MPTCP_PM_ADDR_FLAG_BACKUP : 0; + retry->local.ifindex =3D ssk->sk_bound_dev_if; + + return true; +} + +/* Called with the msk socket lock held, after the subflow has been closed= */ +void mptcp_pm_kernel_retry(struct mptcp_sock *msk, + const struct mptcp_pm_retry *retry) +{ + struct mptcp_subflow_context *subflow; + struct sock *sk =3D (struct sock *)msk; + bool allowed; + + spin_lock_bh(&msk->pm.lock); + allowed =3D msk->pm.extra_subflows < + mptcp_pm_get_limit_extra_subflows(msk); + if (allowed) + msk->pm.extra_subflows++; + spin_unlock_bh(&msk->pm.lock); + + if (!allowed || + __mptcp_subflow_connect(sk, &retry->local, &retry->remote)) + return; + + /* the new subflow is the last one */ + subflow =3D list_last_entry(&msk->conn_list, struct mptcp_subflow_context, + node); + /* from 1 to MAX_TCP_SYNCNT, see mptcp_pm_kernel_retry_check() */ + tcp_sock_set_syncnt(mptcp_subflow_tcp_sock(subflow), + retry->syn_retries); + subflow->retry =3D true; +} + /* Called under PM lock */ void __mptcp_pm_kernel_worker(struct mptcp_sock *msk) { diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index 02a4f479d9d8..257059ffdc7e 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -736,6 +736,10 @@ static void mptcp_check_data_fin(struct sock *sk) if (!__mptcp_check_fallback(msk)) mptcp_send_ack(msk); mptcp_close_wake_up(sk); + + /* not always called from the worker, which closes them */ + if (mptcp_retry_subflows_stale(msk)) + mptcp_schedule_work(sk); } } =20 @@ -2697,8 +2701,11 @@ static void __mptcp_close_ssk(struct sock *sk, struc= t sock *ssk, lock_sock_nested(ssk, SINGLE_DEPTH_NESTING); subflow->closing =3D 1; =20 - if (flags & MPTCP_CF_PUSH) - mptcp_cleanup_ssk_backlog(sk, ssk); + /* also without MPTCP_CF_PUSH: a re-created subflow closed with the msk + * can have been established in between, see + * mptcp_close_retry_subflows() + */ + mptcp_cleanup_ssk_backlog(sk, ssk); =20 /* Borrow the fwd allocated page left-over; fwd memory for the subflow * could be negative at this point, but will be reach zero soon - when @@ -2788,6 +2795,49 @@ static void __mptcp_close_ssk(struct sock *sk, struc= t sock *ssk, } } =20 +/* Re-created subflows not established yet are useless once the msk is + * closed or shut down. When no other subflow can send data, see + * mptcp_retry_subflows_stale(), only the ones still connecting are: a joi= ned + * one is fully established soon. Not called while iterating on the subflo= ws. + */ +static void mptcp_close_retry_subflows(struct sock *sk, bool connecting) +{ + struct mptcp_subflow_context *subflow, *tmp; + struct mptcp_sock *msk =3D mptcp_sk(sk); + + mptcp_for_each_subflow_safe(msk, subflow, tmp) { + struct sock *ssk =3D mptcp_subflow_tcp_sock(subflow); + + if (!subflow->retry || READ_ONCE(subflow->fully_established)) + continue; + + if (connecting) { + if (inet_sk_state_load(ssk) !=3D TCP_SYN_SENT) + continue; + /* another one got established in the meantime */ + if (!mptcp_retry_subflows_stale(msk)) + break; + } + + /* like mptcp_close_ssk(): it can have joined already */ + if (sk->sk_state =3D=3D TCP_ESTABLISHED && + !subflow->close_event_done) { + subflow->close_event_done =3D true; + mptcp_event(MPTCP_EVENT_SUB_CLOSED, msk, ssk, + GFP_KERNEL); + } + + /* Checked without the ssk lock: it can have joined, or been + * established in between, and is then closed anyway. + * __mptcp_close_ssk() cleans its data in the msk backlog, and + * the MPTCP retransmissions cover what it sent. No need to push + * the pending data again. + */ + mptcp_pm_subflow_check_next(msk, subflow); + __mptcp_close_ssk(sk, ssk, subflow, 0); + } +} + void mptcp_close_ssk(struct sock *sk, struct sock *ssk, struct mptcp_subflow_context *subflow) { @@ -2806,6 +2856,12 @@ void mptcp_close_ssk(struct sock *sk, struct sock *s= sk, mptcp_pm_subflow_check_next(mptcp_sk(sk), subflow); =20 __mptcp_close_ssk(sk, ssk, subflow, MPTCP_CF_PUSH); + + /* the caller can iterate on the subflows: the worker closes the + * re-created ones + */ + if (mptcp_retry_subflows_stale(mptcp_sk(sk))) + mptcp_schedule_work(sk); } =20 static unsigned int mptcp_sync_mss(struct sock *sk, u32 pmtu) @@ -2823,6 +2879,8 @@ static void __mptcp_close_subflow(struct sock *sk) mptcp_for_each_subflow_safe(msk, subflow, tmp) { struct sock *ssk =3D mptcp_subflow_tcp_sock(subflow); int ssk_state =3D inet_sk_state_load(ssk); + struct mptcp_pm_retry retry; + bool do_retry; =20 if (ssk_state !=3D TCP_CLOSE && (ssk_state !=3D TCP_CLOSE_WAIT || @@ -2834,7 +2892,10 @@ static void __mptcp_close_subflow(struct sock *sk) if (!skb_queue_empty_lockless(&ssk->sk_receive_queue)) continue; =20 + do_retry =3D mptcp_pm_subflow_retry_check(msk, subflow, &retry); mptcp_close_ssk(sk, ssk, subflow); + if (do_retry) + mptcp_pm_subflow_retry(msk, &retry); } =20 } @@ -3185,6 +3246,9 @@ static void mptcp_worker(struct work_struct *work) if (test_and_clear_bit(MPTCP_WORK_CLOSE_SUBFLOW, &msk->flags)) __mptcp_close_subflow(sk); =20 + if (mptcp_retry_subflows_stale(msk)) + mptcp_close_retry_subflows(sk, true); + if (mptcp_close_tout_expired(sk)) { struct mptcp_subflow_context *subflow, *tmp; =20 @@ -3516,6 +3580,9 @@ bool __mptcp_close(struct sock *sk, long timeout) goto cleanup; } =20 + /* before __mptcp_wr_shutdown() disconnects them */ + mptcp_close_retry_subflows(sk, false); + if (mptcp_data_avail(msk) || timeout < 0 || (sock_flag(sk, SOCK_LINGER) && !sk->sk_lingertime)) { /* If the msk has read data, or the caller explicitly ask it, @@ -4140,7 +4207,12 @@ static void mptcp_shutdown(struct sock *sk, int how) { pr_debug("sk=3D%p, how=3D%d\n", sk, how); =20 - if ((how & SEND_SHUTDOWN) && mptcp_close_state(sk)) + if (!(how & SEND_SHUTDOWN)) + return; + + /* before the state change and __mptcp_wr_shutdown(), as on close */ + mptcp_close_retry_subflows(sk, false); + if (mptcp_close_state(sk)) __mptcp_wr_shutdown(sk); } =20 diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h index 4aa4aedb2ba7..f160e9ac7892 100644 --- a/net/mptcp/protocol.h +++ b/net/mptcp/protocol.h @@ -610,6 +610,8 @@ struct mptcp_subflow_context { bool close_event_done; /* has done the post-closed part, * protected by msk socket lock */ + bool retry; /* re-created after an error, msk lock */ + bool no_retry; /* uses a removed address, msk lock */ u32 lent_mem_frag; u32 remote_nonce; u32 local_nonce; @@ -919,6 +921,37 @@ static inline bool __mptcp_subflow_active(struct mptcp= _subflow_context *subflow) return __tcp_can_send(mptcp_subflow_tcp_sock(subflow)); } =20 +/* Can send data, and is not being closed, e.g. in CLOSE_WAIT */ +static inline bool mptcp_subflow_can_send(struct mptcp_subflow_context *su= bflow) +{ + struct sock *ssk =3D mptcp_subflow_tcp_sock(subflow); + + return __mptcp_subflow_active(subflow) && + inet_sk_state_load(ssk) =3D=3D TCP_ESTABLISHED; +} + +/* Re-created subflows not established yet, while no other subflow can send + * data, or once the msk is no longer established: they cannot join anymor= e, + * see mptcp_finish_join(), or must not keep the connection open. + */ +static inline bool mptcp_retry_subflows_stale(struct mptcp_sock *msk) +{ + struct mptcp_subflow_context *subflow; + struct sock *sk =3D (struct sock *)msk; + bool retry =3D false; + + mptcp_for_each_subflow(msk, subflow) { + if (sk->sk_state =3D=3D TCP_ESTABLISHED && + mptcp_subflow_can_send(subflow)) + return false; + + retry |=3D subflow->retry && + !READ_ONCE(subflow->fully_established); + } + + return retry; +} + void mptcp_subflow_set_active(struct mptcp_subflow_context *subflow); =20 bool mptcp_subflow_active(struct mptcp_subflow_context *subflow); @@ -1139,6 +1172,18 @@ void mptcp_pm_subflow_established(struct mptcp_sock = *msk); bool mptcp_pm_nl_check_work_pending(struct mptcp_sock *msk); void mptcp_pm_subflow_check_next(struct mptcp_sock *msk, const struct mptcp_subflow_context *subflow); + +struct mptcp_pm_retry { + struct mptcp_pm_local local; + struct mptcp_addr_info remote; + u8 syn_retries; +}; + +bool mptcp_pm_subflow_retry_check(struct mptcp_sock *msk, + const struct mptcp_subflow_context *subflow, + struct mptcp_pm_retry *retry); +void mptcp_pm_subflow_retry(struct mptcp_sock *msk, + const struct mptcp_pm_retry *retry); void mptcp_pm_add_addr_received(const struct sock *ssk, const struct mptcp_addr_info *addr); void mptcp_pm_add_addr_echoed(struct mptcp_sock *msk, @@ -1260,6 +1305,11 @@ void __init mptcp_pm_userspace_register(void); void __init mptcp_pm_nl_init(void); void mptcp_pm_worker(struct mptcp_sock *msk); void __mptcp_pm_kernel_worker(struct mptcp_sock *msk); +bool mptcp_pm_kernel_retry_check(struct mptcp_sock *msk, + const struct mptcp_subflow_context *subflow, + struct mptcp_pm_retry *retry); +void mptcp_pm_kernel_retry(struct mptcp_sock *msk, + const struct mptcp_pm_retry *retry); u8 mptcp_pm_get_endp_signal_max(const struct mptcp_sock *msk); u8 mptcp_pm_get_endp_subflow_max(const struct mptcp_sock *msk); u8 mptcp_pm_get_endp_laminar_max(const struct mptcp_sock *msk); --=20 2.25.1 From nobody Thu Nov 5 07:28:49 2026 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=74.125.82.174 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793166119; b=aPxpjZCEZY+QhWueSohi5gVm5O3+Biq41GweUAxpVVXNpsE8ypTu7pPuYP6Rafuk3t5O QefOddMThBZIhvK7F3zNuXR+9DS+VuXVeO1zyqXiZ7CkjlQV6CzEQzmGRpVXR+vW5SCAZ fQ1Dlzay8wc7kVXt0triK8nrOOXvPZmu6ORkY5XMEXW2JTRIgZ64AEYuEkgdJn+9KjIUK OrQrKlbxE5JtTrGYu56IutsxwqsipETrUJ+5kkji5h7Uqq+abYAkN19AL4GQAV5BJ94OI qxNWH2cqPWbyg0jLkUOquDv39C0tplzbX61oCz/hzKSlkoal5JunK+ADM4WHXfL560A== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793166119; h=DMARC-Filter:Received:DKIM-Signature:X-Google-DKIM-Signature: X-Gm-Message-State:X-Gm-Gg:X-Received:Received:From:To:Cc:Subject: Date:Message-Id:X-Mailer:In-Reply-To:References:MIME-Version: Content-Transfer-Encoding; bh=ZSJXeJ0U3dpO9Dn/SRJ5riHzWjhsmdC7lpOaZK2mNqs=; b=KzmsabVtY0SJvYCF+gefdceCEbp40hZbKgHhrom9PlfByovHG6fQxMHqRU7uLy3neC/4 fem3+Hly4gvXUq1+0Z/LwjQkCJF6ISPnsiBa+B5kGLpgviQ5UKte0o38Y18VLILOTXDb5 7tltFPuOKfIUjIKPhrPYzxPeT1+DxUXqbaVrwSLhqG1ACOuxEBTp3la1QhWk5kW39hZGS 3kEP/X+YpjBW9b/374lK46YbfEJ4bZnZnWCOL1cD16uiJp8Bc2NQlykBEY7vkPhHH4BpQ vfdQWqLlpA1HxD1706HG5TxIJersdHacVJeWxxBSpVc9AlvYjB0H42qCOWPFkD7WTzA== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256 header.s=20260707 header.b=isztLseQ; arc=none smtp.remote-ip=74.125.82.174 Received: from mail-dy1-f174.google.com (mail-dy1-f174.google.com [74.125.82.174]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E91C8606A329 for ; Wed, 28 Oct 2026 05:41:58 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org E91C8606A329 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256 header.s=20260707 header.b=isztLseQ Received: by mail-dy1-f174.google.com with SMTP id 5a478bee46e88-36a0f27c9f4so971129eec.1 for ; Tue, 27 Oct 2026 22:41:58 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20260707; t=1793166118; x=1793770918; darn=lists.linux.dev; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to:content-type; bh=ZSJXeJ0U3dpO9Dn/SRJ5riHzWjhsmdC7lpOaZK2mNqs=; b=isztLseQ9MHFr/Hq5WtwcZIQy6dxiR07pb266qsP9EWeVYWWUPHpbMvHk/C7Ur4/v5 PMv3ni9KrlBLmWWTMPlI14uu/zmrIv5+dlqrTpynx+bV8BeCpSY+xTTnbEu786S3U6nM nRGbsiPSOAgNO1yTRMDiiW8klqjJEtwVpptxVY5BkZAvlF9eJujEHISBQborPV4S3dXW 1CgrykAlnE6KwekiIIsSGxo4wAvU/M6GCeGgdBO0h1mM3+FgmeVdrevDO7gKzC2U+bC1 24YBe+yFIcLbeByaDJYUGNamSY3Revua54UHQDw/1l5pDmugVUb1zIdaTGWFPNMx+k7X taEw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20260707; t=1793166118; x=1793770918; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-gg:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to:content-type; bh=ZSJXeJ0U3dpO9Dn/SRJ5riHzWjhsmdC7lpOaZK2mNqs=; b=y4dAaWN+N6uUcW9yX/Ap7fiNtvAeLjcigYncVQDnTJW4BTXJHZNFeedKF8AZJE3zBe uuLOwQt5CFdAnv/KRxmpBC2sZ1smnMUFHrvvpTTvLDzP+lamT3q6JMrl7AhXqAAAHBwm igyfeLv2Q1lBi+raNGlx/2zF0mSRhmijnPkk6kMjVGOzcMVymN78evO2rcrPaG0ztbxm uM1wJKboe4mrgMyy6du2yALyIeLF3RZu4a9Kf/ovCKNe0WSqg8jooxF9c30RcDhQWNwk tMp9MKFsuu/1D3OalaBL+GUpkbBWXotReLTwfwpy4mvuZkhyowXdDDGcqaSi0p08BkZM c3jA== X-Gm-Message-State: AFq9FYIWGs3wRxBZpoFuAPgvXkkfpMFSInwl3VLtrhSVXmROTPnYmw8F i9Ph8S36TdtHHEprvbgAXXdaoy/Xg0hzpAmnS3jZpi7MU/xZuaB7KjZOj4XymQ== X-Gm-Gg: AYBFou1inYlrEa2VWaHX+GhgXusf6vccav1kgIxOflN3P6j2QjcFof2wc/2biH3YrEC w6Qx8dBDODmWZiH1ngWojdmixTs8okP33DO2ruknYJSjgq0juRd2DM5tVMY8GEnimLkUtlmff0I 4LMoaY85iWk4nux9PK7a7Wpt6zHm2KUI2hiWW8bTY63SdafTWcfUtlfVBPwgnv1nVta/FXPWetA 80cgvxn1vv5v1JztuExzRKatuJDprzippQjvkEBdVjzpAe3Hlgb+y7lTZyPvbVzxMMru/jZRmaw ri1I2sghTuj4gHjriOO4UdUVlFyunEUbm0rx57RMONfzi/Y9TNVo3UGJ/vtUy9QnQb3JR3tI3cV EOQiTn+MegyKnwI+2AGBeGT2oTGo3CwI5NnlsZ8wuQVl6y1UzSyTfI0nCldL7R3IAMZUt+5PIR/ hBDCD5/1uIpfNwUOeWrXhNKYTGOztiyqfz3pDkfQVzt0UHGF2mhutdfvDlP9I0u6y4mn4WBJIU7 lf2Jz9Seyq/QW5AHozKWgHY1w2p/wR9BssvQ6rK73vHGFi7ZSXphLdrzabSfWv2aZ+pmwrvgXUQ H/ISKAAODiQzgOjtWUJaSPnRKYAK8kel1DPJvOgq0LL4ur1DP+et0sl7BMnagS1sgrjpUyUnLSb qrtCdH7b/yuNdxyPBk7iovcGib3KFhyp5s47hiPQYqbVdQa0giLEesSEhW1EhoCc2z/VbsCf08d bId+M/6TcF1up4s5IEFIY= X-Received: by 2002:a05:693c:8956:10b0:369:44b3:99c0 with SMTP id 5a478bee46e88-36a2036d4e2mr2156013eec.8.1793166117739; Tue, 27 Oct 2026 22:41:57 -0700 (PDT) Received: from ramen-dev-security-2.asia-south1-c.c.ramen-dev-345017.internal (90.156.200.35.bc.googleusercontent.com. [35.200.156.90]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-36a237be80csm5860973eec.2.2026.10.27.22.41.56 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 27 Oct 2026 22:41:57 -0700 (PDT) From: Anil Kaushik To: mptcp@lists.linux.dev Cc: Anil Kaushik Subject: [PATCH mptcp-next v12 5/6] selftests: mptcp: pm_nl_ctl: support the subflow-retries limit Date: Wed, 28 Oct 2026 05:41:42 +0000 Message-Id: <20261028054143.3222998-6-anilkaushikwireless@gmail.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20261028054143.3222998-1-anilkaushikwireless@gmail.com> References: <20261028054143.3222998-1-anilkaushikwireless@gmail.com> X-Mailing-List: mptcp@lists.linux.dev List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" 'pm_nl_ctl limits' can now set the subflow-retries limit with a third value, and shows it when the kernel supports it. pm_netlink.sh checks its default value, that a value above the maximum is refused, that it can be set, and that it is kept when only the other limits are set. This is only done with pm_nl_ctl for the moment: iproute2 does not support this limit yet. Signed-off-by: Anil Kaushik --- Notes: v12: - check the limit is kept when only the other limits are set (netdev Sashiko) v9: - try the value above the maximum after setting 0, not the default value, which is also the maximum: a refused value is then told apart from a clamped one (netdev Sashiko) v8: - the default value is now 127 v7: - also check that the maximum value, 127, is accepted (netdev Sashiko) v5: - new (Matthieu) .../testing/selftests/net/mptcp/pm_netlink.sh | 53 ++++++++++++++++++- tools/testing/selftests/net/mptcp/pm_nl_ctl.c | 34 +++++++++--- 2 files changed, 78 insertions(+), 9 deletions(-) diff --git a/tools/testing/selftests/net/mptcp/pm_netlink.sh b/tools/testin= g/selftests/net/mptcp/pm_netlink.sh index 21bfe1311f11..5c27836f527c 100755 --- a/tools/testing/selftests/net/mptcp/pm_netlink.sh +++ b/tools/testing/selftests/net/mptcp/pm_netlink.sh @@ -46,15 +46,20 @@ trap cleanup EXIT =20 mptcp_lib_ns_init ns1 =20 +# $3: subflow retries, only shown by pm_nl_ctl, if supported format_limits() { local accept=3D"${1}" local subflows=3D"${2}" + local retries=3D"${3}" =20 if mptcp_lib_is_ip_mptcp; then # with a space at the end printf "add_addr_accepted %d subflows %d \n" "${accept}" "${subflows}" else printf "accept %d\nsubflows %d\n" "${accept}" "${subflows}" + if [ -n "${retries}" ]; then + printf "subflow_retries %d\n" "${retries}" + fi fi } =20 @@ -75,6 +80,22 @@ get_limits_nb() { fi } =20 +# The subflow retries limit is only set and shown with pm_nl_ctl for now. +# Prints its default value if it is supported. +get_default_retries() { + if mptcp_lib_is_ip_mptcp; then + return + fi + + if ip netns exec "${ns1}" ./pm_nl_ctl limits | + grep -q "^subflow_retries"; then + echo 127 + elif mptcp_lib_expect_all_features; then + # missing feature: the defaults limits check will fail + echo 127 + fi +} + format_endpoints() { mptcp_lib_pm_nl_format_endpoints "${@}" } @@ -154,8 +175,10 @@ mptcp_lib_subtests_last_ts_reset check "show_endpoints" "" "defaults addr list" =20 default_limits=3D"$(get_limits)" +default_retries=3D"$(get_default_retries)" if mptcp_lib_expect_all_features; then - check "get_limits" "$(format_limits 0 2)" "defaults limits" + check "get_limits" "$(format_limits 0 2 "${default_retries}")" \ + "defaults limits" fi =20 add_endpoint 10.0.1.1 @@ -224,7 +247,33 @@ check "get_limits" "${default_limits}" "subflows above= hard limit" =20 set_limits ${max_limits} ${max_limits} flush_endpoint ## to make sure it doesn't affect the limits -check "get_limits" "$(format_limits ${max_limits} ${max_limits})" "set lim= its" +max_limits_out=3D"$(format_limits ${max_limits} ${max_limits} \ + "${default_retries}")" +check "get_limits" "${max_limits_out}" "set limits" + +if [ -n "${default_retries}" ]; then + ip netns exec "${ns1}" ./pm_nl_ctl limits ${max_limits} ${max_limits} 0 + check "get_limits" "$(format_limits ${max_limits} ${max_limits} 0)" \ + "set subflow retries" + + # not given: unchanged + set_limits ${max_limits} ${max_limits} + check "get_limits" "$(format_limits ${max_limits} ${max_limits} 0)" \ + "subflow retries kept" + + # not from the default: a refused value differs from a clamped one + ip netns exec "${ns1}" ./pm_nl_ctl limits ${max_limits} ${max_limits} \ + 128 2>/dev/null + check "get_limits" "$(format_limits ${max_limits} ${max_limits} 0)" \ + "subflow retries above hard limit" + + ip netns exec "${ns1}" ./pm_nl_ctl limits ${max_limits} ${max_limits} \ + 127 + check "get_limits" "$(format_limits ${max_limits} ${max_limits} 127)" \ + "set max subflow retries" + ip netns exec "${ns1}" ./pm_nl_ctl limits ${max_limits} ${max_limits} \ + "${default_retries}" +fi =20 flush_endpoint add_endpoint 10.0.1.1 diff --git a/tools/testing/selftests/net/mptcp/pm_nl_ctl.c b/tools/testing/= selftests/net/mptcp/pm_nl_ctl.c index 78180da1efcc..41467b997018 100644 --- a/tools/testing/selftests/net/mptcp/pm_nl_ctl.c +++ b/tools/testing/selftests/net/mptcp/pm_nl_ctl.c @@ -39,7 +39,7 @@ static void syntax(char *argv[]) fprintf(stderr, "\tset [] [id ] flags [no]backup|[no]fullmesh [po= rt ] [token ] [rip ] [rport ]\n"); fprintf(stderr, "\tflush\n"); fprintf(stderr, "\tdump\n"); - fprintf(stderr, "\tlimits [ ]\n"); + fprintf(stderr, "\tlimits [ []]\n"); fprintf(stderr, "\tevents\n"); fprintf(stderr, "\tlisten \n"); exit(0); @@ -1217,6 +1217,7 @@ int flush_addrs(int fd, int pm_family, int argc, char= *argv[]) static void print_limits(struct nlmsghdr *nh, int pm_family, int total_len) { struct rtattr *attrs; + const char *name; uint32_t max; =20 for (; NLMSG_OK(nh, total_len); nh =3D NLMSG_NEXT(nh, total_len)) { @@ -1235,13 +1236,22 @@ static void print_limits(struct nlmsghdr *nh, int p= m_family, int total_len) while (RTA_OK(attrs, len)) { int type =3D attrs->rta_type; =20 - if (type !=3D MPTCP_PM_ATTR_RCV_ADD_ADDRS && - type !=3D MPTCP_PM_ATTR_SUBFLOWS) + switch (type) { + case MPTCP_PM_ATTR_RCV_ADD_ADDRS: + name =3D "accept"; + break; + case MPTCP_PM_ATTR_SUBFLOWS: + name =3D "subflows"; + break; + case MPTCP_PM_ATTR_SUBFLOW_RETRIES: + name =3D "subflow_retries"; + break; + default: goto next; + } =20 memcpy(&max, RTA_DATA(attrs), 4); - printf("%s %u\n", type =3D=3D MPTCP_PM_ATTR_SUBFLOWS ? - "subflows" : "accept", max); + printf("%s %u\n", name, max); =20 next: attrs =3D RTA_NEXT(attrs, len); @@ -1254,15 +1264,17 @@ int get_set_limits(int fd, int pm_family, int argc,= char *argv[]) char data[NLMSG_ALIGN(sizeof(struct nlmsghdr)) + NLMSG_ALIGN(sizeof(struct genlmsghdr)) + 1024]; - uint32_t rcv_addr =3D 0, subflows =3D 0; + uint32_t rcv_addr =3D 0, subflows =3D 0, retries =3D 0; int cmd, len =3D sizeof(data); struct nlmsghdr *nh; int off =3D 0; =20 /* limit */ - if (argc =3D=3D 4) { + if (argc =3D=3D 4 || argc =3D=3D 5) { rcv_addr =3D atoi(argv[2]); subflows =3D atoi(argv[3]); + if (argc =3D=3D 5) + retries =3D atoi(argv[4]); cmd =3D MPTCP_PM_CMD_SET_LIMITS; } else { cmd =3D MPTCP_PM_CMD_GET_LIMITS; @@ -1287,6 +1299,14 @@ int get_set_limits(int fd, int pm_family, int argc, = char *argv[]) memcpy(RTA_DATA(rta), &subflows, 4); off +=3D NLMSG_ALIGN(rta->rta_len); =20 + if (argc =3D=3D 5) { + rta =3D (void *)(data + off); + rta->rta_type =3D MPTCP_PM_ATTR_SUBFLOW_RETRIES; + rta->rta_len =3D RTA_LENGTH(4); + memcpy(RTA_DATA(rta), &retries, 4); + off +=3D NLMSG_ALIGN(rta->rta_len); + } + /* do not expect a reply */ len =3D 0; } --=20 2.25.1 From nobody Thu Nov 5 07:28:49 2026 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=74.125.82.172 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793166121; b=wZ9UMYVz9U99+2R57tPHBhWIWKVRUzuALJiCLmR3be336cHM1R6PLMaj+J08apsatDVw q+bIJla8EImlnm0dOoKWF8LnPxgb4XQWfxEUEAOwQRJlN4BQQqVZe3vyu80YsuBfsCQFS UpmtDB8oOvBqdtoKITcXfKYZ/D+WzkL5Hal6TnwmCIvbOI2mltVSoe1p56t1HExSVFqRx J53Lyt2cJ34Fe4qflFVtfvAyQW/gHRXKdBfRZKBb/60qJSseZXV7DeQOFOy5FaZW4x1t1 gfVgfNccdR7nQY0IJySt2fPczr/N/AMPOZcDWzt57yqNuDE8T55/EkccK9S3TuuhWlQ== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793166121; h=DMARC-Filter:Received:DKIM-Signature:X-Google-DKIM-Signature: X-Gm-Message-State:X-Gm-Gg:X-Received:Received:From:To:Cc:Subject: Date:Message-Id:X-Mailer:In-Reply-To:References:MIME-Version: Content-Transfer-Encoding; bh=lJj6hmucyq41wGyKxJPfOefiiIU/El5yyKlWEgxugPY=; b=rmTOqmQWZ3+FSyn6dpqsV6M4NUpHTrDiG/pAlzgB4oHvQ9WnlhWf1+jwj6nTjctshqO8 88pOy7vGPGB+ycwijnQ8+Ymp7DT2gbMLRG/k5Fpfc3TbYTei12wxNrvSq/K8fkPcc0NvR kw0EzHXjpGbF6aDyLhzL1ntEX70GzhWz0oZsIV+VmaWqRoigCgWXB5H3EhxEG3Zbkecbo axDFwF4OIUvG4z2vaQmAWF49zjQfKBc9IAygkL4RwmG9d2DRQlQcPR6XOVNSFpRgxVdod e3xKKxss9CLr7MDRCieUv2OG0n0Bfq3NOhVGDwxqD8kvz1j7TlQ2fMMQTo9tF0PEWFQ== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256 header.s=20260707 header.b=OO+3Pj45; arc=none smtp.remote-ip=74.125.82.172 Received: from mail-dy1-f172.google.com (mail-dy1-f172.google.com [74.125.82.172]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E5A01606A329 for ; Wed, 28 Oct 2026 05:42:00 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org E5A01606A329 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256 header.s=20260707 header.b=OO+3Pj45 Received: by mail-dy1-f172.google.com with SMTP id 5a478bee46e88-3645f0f3fcdso1060031eec.0 for ; Tue, 27 Oct 2026 22:42:00 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20260707; t=1793166120; x=1793770920; darn=lists.linux.dev; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to:content-type; bh=lJj6hmucyq41wGyKxJPfOefiiIU/El5yyKlWEgxugPY=; b=OO+3Pj45giYVxdH6cQr23FvgXfgv16QTkCsBqRWvHI9FiblFgY/tJzWGmnjMvne+vl N3NIcmaKboVfg9s0Wz88BmT6g5aCDxNsmWhCpxaT0g+8zc2gU7ZPH5S0L5OcyPV95ZOI 69pYgQ3ihBqcw/9XHDGVIJHz0UdILS5uNiIq7w817pXShS703E+QH2DRXJskDaMWBm0R +00LjlkKwbiiOYxAoXLSSiBSMUCVsN5BmAyDjigUN49uiMzvr9nzA0O9zMEq1V1LRSCp 3pidtzC00ji92pt+zBl6RZnlEQFaYHXJ7C7E6MUsUwJidLC48Wz2MAzC9pMCMRpN8WQo Arzg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20260707; t=1793166120; x=1793770920; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-gg:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to:content-type; bh=lJj6hmucyq41wGyKxJPfOefiiIU/El5yyKlWEgxugPY=; b=aJE21zp6hX0W+PnuJ6Q6G3+Xn0LM2PtsOLn/Oish2lGa6yKd3brsSYqyqxglqGc0e7 zUXcYTChf/DLYaJvYX7UxK3nt6bPy+OFCAC0f00Dt6zXCpEHtcXRcXvuuyd8WPlETRs5 aT4bn8nH8tLhYBWS2kkfrKsKEiHAIUWzRkudtQygVrnGG3DwFlSNkaXNqCKgxMbFIJvf 3oycOUmmh5lNyreZjl9OLSIwj4PjqZXcga2myEJwMdKLBBzGe7SKcRYv80UDhBFwzmZm LlPbEDnuZBrlJxr6GY3z05blO3XWuAeB5PkNE/Thi28atd4T7BV7pR6x83d9WWdRVD38 tJnQ== X-Gm-Message-State: AFq9FYJSy6e+stNPRoh0+gYJQGKv/P/cCmNIHX2Dxd4cgGJ9QFocsk9s 8le/dktSUZr6A5KRGgebmVuWJXpqfnSEYX9j1h4GZHfsLiaRYV5WgBldwYiKmQ== X-Gm-Gg: AYBFou18MeO+rs54Pj2w3zy3wGT7aOTmf9huTo8VbwC1mnLD2YE2RStXvglltdE4jya 0DLEXs284f7zGJf00gF4xHABf2cazOzNKn0YZnLAchU/xWsQP7r4rT9OrIJKZBCc8UojAwzUaOI pNClhkJOB8m+F/763f5IjwoZTG+mR+fxmuEWcoM/tXYoU/Tnsjhf3zVYxcFCTNMVNlg1nMFGRuI rDeUnqbF/MRqP/c1DemCNmRW5LdY3HfVflCHsOsv5GjUrr97+jjPGcZ+/x79TIJU46AkqqnE9L5 zDEOgtNxylLgSXTIINVAdT1rUbh1uXlhEwAEKTrM0EDJY9lQ5dVDij0EwUK/QS50RfRWr91TrlG cUGMtpuA47JRjqLlKmBOJtbWElbW47bfKdai6J5kG+GHbZJGzB96/Y4hKSAtnveH2q9i+4lyAZu UyX0jteKHze9OIci8MbdU8TExUfnvOSJlmVv0pMtwTgmm5Di/nF8vopNIKZ6bRvn5VlNKQPI1J2 V/GCusB2JN9c3/H5dGC/Q8COEKSRD9FDpkRR5fpFQXoDXwzN6jDdshnJEp/ZxzyasewiM5IFSxf GEP+HQEI9pES3DRSfYrT7yp+as4Pq+vof/cWqDgfo8qZD9GaPK+AFn9wjm3X+rDRFCi0VuhR48X MJu+/iCVI7AM+5qaFoIzNhj8L46etkn75yQuXJhhWJTLj2ybdiD5Qgxa8zfBgdrmuXc308oTIMg == X-Received: by 2002:a05:693c:821b:b0:36a:1294:59e0 with SMTP id 5a478bee46e88-36a20179d20mr1957453eec.24.1793166119661; Tue, 27 Oct 2026 22:41:59 -0700 (PDT) Received: from ramen-dev-security-2.asia-south1-c.c.ramen-dev-345017.internal (90.156.200.35.bc.googleusercontent.com. [35.200.156.90]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-36a237be80csm5860973eec.2.2026.10.27.22.41.58 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 27 Oct 2026 22:41:59 -0700 (PDT) From: Anil Kaushik To: mptcp@lists.linux.dev Cc: Anil Kaushik Subject: [PATCH mptcp-next v12 6/6] selftests: mptcp: join: validate subflow retry after link failure Date: Wed, 28 Oct 2026 05:41:43 +0000 Message-Id: <20261028054143.3222998-7-anilkaushikwireless@gmail.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20261028054143.3222998-1-anilkaushikwireless@gmail.com> References: <20261028054143.3222998-1-anilkaushikwireless@gmail.com> X-Mailing-List: mptcp@lists.linux.dev List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Test the subflow-retries limit, with its default value, and a long connection in the background: drop the packets the client sends from the additional subflow address with netfilter, without bringing the link down, until the subflow is closed and re-created. Let them through again once the SYN of the new subflow has been retransmitted more times than tcp_syn_retries allows, and check the subflow comes back from the same address. Then do the same with the initial subflow. A second test closes the connection while a subflow is being re-created, and checks the netlink events. Only the client sends data: the server reads it all first, in sendfile mode, and keeps its side open. The client gets a big MPTCP send buffer compared to its subflows, and both paths are blocked: the data left in it is never sent, nor the DATA_FIN, so only the close of the MPTCP socket can stop the subflow being re-created. Only the client is closed: it has nothing left to read, so the connection is not closed with a fastclose, which would reset all the subflows anyway. The check is skipped if a fastclose happens. The big files used for the long connection are emptied at the end. A third test checks the only subflow is not re-created: there is no other subflow to send data. The tests are skipped if pm_nl_ctl does not show the new limit, or if the filter rules cannot be set. Signed-off-by: Anil Kaushik --- Notes: v12: - wait for the client side of a re-created subflow to be fully established before going on: the close would close it too otherwise (netdev Sashiko) - the third test only checks the subflow is not re-created, say only that (netdev Sashiko) v11: - the third test checks the only subflow is not re-created, and the path-back test is gone: a subflow is only re-created while another one can send data - the close test keeps the initial subflow while checking: without the fix, it would no longer pass when the initial subflow closes after a few retransmissions; a SUB_CLOSED event for the re-created subflow v10: - new test: the path of the only subflow comes back before the close timeout, and the connection stays open (sashiko.dev) The path comes back as soon as the subflow is re-created, with a 30s close timeout, longer than the SYN backoff, and its transfer has a longer poll timeout, with no data at all while the only path is blocked: both are needed on a slow debug kernel v9: - wait for absolute counter values, read before blocking the path, or 0 and 1 in the new netns: the subflow can be re-created before a later read (netdev Sashiko) - check that the connection is established before blocking it, in the close test and the new one (netdev Sashiko) - the close test blocks the other path too, with a big msk send buffer: the pending data and the DATA_FIN no longer close the subflow being re-created, only the close of the MPTCP socket can. Checked: both the close test and the new test fail without their fix - new test: the only subflow is re-created, and the connection is still closed after the close timeout - $sinfail as the server input, kill errors ignored, clearer failure message, $cout and $sout emptied too - the server of the second test reads all the data from the client first, in sendfile mode, instead of blocking on a FIFO in poll mode: the client always has data in flight (netdev Sashiko) v8: - comment in run_tests() matching the new condition (netdev Sashiko) - a separate test closes the connection while a subflow is re-created: the server sends nothing but keeps its side open, and only the client is closed, so there is no fastclose, which would reset all the subflows anyway; the check is skipped if one happens (netdev Sashiko) v7 (netdev Sashiko): - the test_linkfail=3D1/2 modes regenerate the shared files when they are empty, e.g. when running link_failure_tests() twice - read the MP_JOIN ACK counter before letting the packets through, and do not compare the ports, they can be reused v6 (Sashiko): - use the slowwait helpers from net/lib.sh - longer first wait, while the 128 MB files are created - skip if the filter rules cannot be set, check each drop rule (netdev Sashiko) - empty the big files at the end, cinsent too, keep the variables (netdev Sashiko) v5 (Matthieu): - skipped if pm_nl_ctl does not show the new limit - wait for the SYN retransmissions instead of a sleep, with tcp_syn_linear_timeouts=3D0 - helper for the check after the close - slower links with short queues, so the transfer lasts the whole test on any machine, longer timeout (killed at the end) v4: - default limit, no sysctl or MIB counter - more SYN retransmissions than tcp_syn_retries - close the connection while a subflow is re-created - check the netlink events - check the waits and the new subflow port, remove the big files at the end (Sashiko) v3: - check the subflow address, create the files before the background job v2: - one test, with netfilter .../testing/selftests/net/mptcp/mptcp_join.sh | 342 +++++++++++++++++- 1 file changed, 334 insertions(+), 8 deletions(-) diff --git a/tools/testing/selftests/net/mptcp/mptcp_join.sh b/tools/testin= g/selftests/net/mptcp/mptcp_join.sh index c3ccce96b45b..2b847d90674e 100755 --- a/tools/testing/selftests/net/mptcp/mptcp_join.sh +++ b/tools/testing/selftests/net/mptcp/mptcp_join.sh @@ -52,6 +52,7 @@ nr_blank=3D6 # These var are used only in some tests, make sure they are not already set unset FAILING_LINKS unset test_linkfail +unset server_in unset addr_nr_ns1 unset addr_nr_ns2 unset cestab_ns1 @@ -1038,7 +1039,12 @@ do_transfer() fi =20 extra_srv_args=3D"$extra_args $extra_srv_args" - if [ "$test_linkfail" -gt 1 ];then + if [ -n "${server_in}" ]; then + # the server reads all the data from the client before sending + # this file: it does not block on its input + extra_srv_args=3D"$extra_srv_args -m sendfile" + listener_in=3D"${server_in}" + elif [ "$test_linkfail" -gt 1 ]; then listener_in=3D"${sinfail}" fi ip netns exec ${listener_ns} \ @@ -1135,9 +1141,9 @@ run_tests() cinfail=3D$(mktemp) fi make_file "$cinfail" "client" $size - # create the input file for the failure test when - # the first failure test run - elif [ "$test_linkfail" -ne 0 ] && [ -z "$cinfail" ]; then + # create the input file for the failure test, when + # it is missing or has been emptied + elif [ "$test_linkfail" -ne 0 ] && [ ! -s "$cinfail" ]; then # the client file must be considerably larger # of the maximum expected cwin value, or the # link utilization will be not predicable @@ -1146,23 +1152,27 @@ run_tests() size=3D$((size*8192)) size=3D$((size + ( RANDOM % 8192) )) =20 - cinfail=3D$(mktemp) + if [ -z "$cinfail" ]; then + cinfail=3D$(mktemp) + fi make_file "$cinfail" "client" $size fi =20 - if [ "$test_linkfail" -gt 2 ]; then + if [ "$test_linkfail" -gt 2 ] && [ -z "${server_in}" ]; then size=3D$test_linkfail =20 if [ -z "$sinfail" ]; then sinfail=3D$(mktemp) fi make_file "$sinfail" "server" $size - elif [ "$test_linkfail" -eq 2 ] && [ -z "$sinfail" ]; then + elif [ "$test_linkfail" -eq 2 ] && [ ! -s "$sinfail" ]; then size=3D$((RANDOM%16)) size=3D$((size+1)) size=3D$((size*2048)) =20 - sinfail=3D$(mktemp) + if [ -z "$sinfail" ]; then + sinfail=3D$(mktemp) + fi make_file "$sinfail" "server" $size fi =20 @@ -2151,6 +2161,203 @@ wait_attempt_fail() return 1 } =20 +# $1: timeout in seconds ; $2: ns ; $3: counter ; $4: increment, 1 by defa= ult +wait_counter_inc() +{ + slowwait_for_counter "${1}" "${4:-1}" \ + mptcp_lib_get_counter "${2}" "${3}" >/dev/null +} + +# $1: timeout ; $2: ns ; $3: counter ; $4: value to reach +wait_counter_ge() +{ + slowwait "${1}" until_counter_is ">=3D ${4}" \ + mptcp_lib_get_counter "${2}" "${3}" >/dev/null +} + +# $1: client address ; prints the local address and port of its subflow +sf_from() +{ + ip netns exec $ns2 ss -tnH state established src "${1}" | + awk '{ print $3; exit }' +} + +# the client got the 4th ACK of the MP_JOIN +sf_fully_established() +{ + ip netns exec $ns2 ss -tniH state established src "${1}" | + grep -q "tcp-ulp-mptcp flags:[A-Za-z]*e" +} + +has_subflow_retries() +{ + ip netns exec $ns2 ./pm_nl_ctl limits | grep -q "^subflow_retries" +} + +# the client packets are dropped with rules in this chain +init_nft_filter() +{ + init_nftables + if ! ip netns exec $ns2 nft list chain ip filter OUTPUT \ + &>/dev/null; then + mark_as_skipped "unable to set the filter rules" + return 1 + fi +} + +# $1: client address +nft_drop_from() +{ + ip netns exec $ns2 nft add rule ip filter OUTPUT ip saddr "${1}" drop +} + +# $1: client address to block +# +# The link stays up, but the client packets from this address are dropped: +# the subflow using it is closed after a few retransmissions, and re-creat= ed. +# The packets go through again once the SYN has been retransmitted more ti= mes +# than tcp_syn_retries allows: the new subflow still connects thanks to the +# subflow-retries limit. +sf_retry_after_block() +{ + local before ack_rx syn_tx + + before=3D$(sf_from "${1}") + + print_check "subflow from ${1}" + if [ -z "${before}" ]; then + fail_test "no established subflow from ${1} before the block" + return + fi + + # read before the block: the subflow can be re-created right after it + syn_tx=3D$(mptcp_lib_get_counter $ns2 "MPTcpExtMPJoinSynTx") + if ! nft_drop_from "${1}"; then + fail_test "unable to drop the packets from ${1}" + return + fi + if ! wait_counter_ge "${timeout_poll}" $ns2 "MPTcpExtMPJoinSynTx" \ + $((syn_tx + 1)); then + ip netns exec $ns2 nft flush chain ip filter OUTPUT + fail_test "subflow from ${1} not re-created" + return + fi + # tcp_syn_retries=3D1: one more retransmission than allowed + if ! wait_counter_inc "${timeout_poll}" \ + $ns2 "TcpExtTCPSynRetrans" 2; then + ip netns exec $ns2 nft flush chain ip filter OUTPUT + fail_test "SYN from ${1} not retransmitted enough" + return + fi + # read before the flush: the next SYN can be sent right after it + ack_rx=3D$(mptcp_lib_get_counter $ns1 "MPTcpExtMPJoinAckRx") + ip netns exec $ns2 nft flush chain ip filter OUTPUT + + if ! wait_counter_ge "${timeout_poll}" $ns1 "MPTcpExtMPJoinAckRx" \ + $((ack_rx + 1)); then + fail_test "re-created subflow from ${1} not established" + return + fi + + # before a close, which would close it too if not fully established + if ! slowwait "${timeout_poll}" sf_fully_established "${1}"; then + fail_test "no fully established subflow from ${1}" + else + print_ok + fi +} + +# $1: ns ; prints the number of MP_FASTCLOSE sent and received +fastclose_nr() +{ + local tx rx + + tx=3D$(mptcp_lib_get_counter "${1}" "MPTcpExtMPFastcloseTx") + rx=3D$(mptcp_lib_get_counter "${1}" "MPTcpExtMPFastcloseRx") + echo $((${tx:-0} + ${rx:-0})) +} + +no_sf_connecting() +{ + ! ip netns exec $ns2 ss -tnH state syn-sent | grep -q . +} + +# The client has nothing left to read: it closes the connection without a +# fastclose, which would reset all the subflows anyway. +kill_client() +{ + local pid + + for pid in $(ip netns pids $ns2); do + if [ "$(cat "/proc/${pid}/comm" 2>/dev/null)" =3D mptcp_connect ] + then + kill "${pid}" 2>/dev/null + fi + done +} + +# $1: why the subflow is not being re-created before the close, if it is n= ot +# $2: number of MP_FASTCLOSE before the close +chk_no_sf_connecting() +{ + local closed + + print_check "no subflow connecting after close" + if [ -n "${1}" ]; then + fail_test "${1}" + return + fi + + # closed with the MPTCP socket + slowwait "${timeout_poll}" no_sf_connecting + closed=3D$? + if [ "$(fastclose_nr $ns2)" -gt "${2}" ]; then + print_skip "closed with a fastclose, resetting all the subflows" + elif [ "${closed}" -eq 0 ]; then + print_ok + else + fail_test "subflow still connecting after close" + fi +} + +# Slow links with short queues: the transfer lasts the whole test on any +# machine, and the blocked subflow always has data in flight. +sf_retry_init() +{ + local i + + for i in 1 3; do + tc -n $ns1 qdisc add dev ns1eth$i root netem \ + rate 4mbit limit 30 delay 1ms + tc -n $ns2 qdisc add dev ns2eth$i root netem \ + rate 4mbit limit 30 delay 1ms + done + ip netns exec $ns2 sysctl -q net.ipv4.tcp_retries2=3D3 + ip netns exec $ns2 sysctl -q net.ipv4.tcp_syn_retries=3D1 + ip netns exec $ns2 sysctl -q net.ipv4.tcp_syn_linear_timeouts=3D0 + pm_nl_set_limits $ns1 0 4 + pm_nl_set_limits $ns2 0 2 + pm_nl_add_endpoint $ns2 10.0.3.2 dev ns2eth3 flags subflow + # created here, not in the background job, for cleanup() + if [ -z "$cinfail" ]; then + cinfail=3D$(mktemp) + fi + if [ -z "$sinfail" ]; then + sinfail=3D$(mktemp) + fi +} + +sf_retry_cleanup() +{ + ip netns exec $ns2 nft flush chain ip filter OUTPUT + # big files: empty them, the next tests write their own content + : > "$cinfail" + : > "$sinfail" + : > "$cinsent" + : > "$cout" + : > "$sout" +} + set_userspace_pm() { local ns=3D$1 @@ -2585,6 +2792,125 @@ link_failure_tests() chk_stale_nr $ns2 1 -1 2 chk_link_usage $ns2 ns2eth3 $cinsent 50 fi + + # subflows closed after a silent link failure, then re-created: the + # additional one, then the initial one + if reset_with_events "subflow retry after link failure" && + continue_if has_subflow_retries && init_nft_filter; then + sf_retry_init + # killed at the end: the timeout only stops a stuck test + { timeout_test=3D600 test_linkfail=3D131072 \ + run_tests $ns1 $ns2 10.0.1.1 & } 2>/dev/null + local tests_pid=3D$! + + # the 128 MB files are created first, that can take a while + wait_counter_ge $((timeout_poll * 4)) \ + $ns1 "MPTcpExtMPJoinAckRx" 1 + sf_retry_after_block 10.0.3.2 + sf_retry_after_block 10.0.1.2 + mptcp_lib_kill_group_wait $tests_pid + kill_events_pids + + join_syn_tx=3D3 chk_join_nr 3 3 3 + chk_evt_nr ns2 MPTCP_LIB_EVENT_SUB_ESTABLISHED 3 + chk_evt_nr ns2 MPTCP_LIB_EVENT_SUB_CLOSED 2 error 2 + sf_retry_cleanup + fi + + # close the connection while a subflow is being re-created + if reset_with_events "subflow retry, close while connecting" && + continue_if has_subflow_retries && init_nft_filter; then + sf_retry_init + # A big msk send buffer, compared to the subflow ones: when the + # client is closed, some data is not given to any subflow yet, + # so the DATA_FIN, which would also close the subflow being + # re-created, is not sent. + ip netns exec $ns2 sysctl -q \ + net.ipv4.tcp_wmem=3D"1048576 65536 262144" + # The server reads until the client closes, and sends nothing: + # the client has nothing to read, and the connection stays + # established. The transfer is stopped on purpose, its result + # is not checked. + : > "$sinfail" + { timeout_test=3D600 test_linkfail=3D131072 server_in=3D"$sinfail" \ + run_tests $ns1 $ns2 10.0.1.1 >/dev/null & } 2>/dev/null + local tests_pid=3D$! + + local not_ready=3D"" syn_tx + if ! wait_counter_ge $((timeout_poll * 4)) \ + $ns1 "MPTcpExtMPJoinAckRx" 1; then + not_ready=3D"no additional subflow before the block" + else + # read before the block: the subflow can be re-created + # right after it + syn_tx=3D$(mptcp_lib_get_counter $ns2 \ + "MPTcpExtMPJoinSynTx") + if ! nft_drop_from 10.0.3.2; then + not_ready=3D"unable to drop the packets" + elif ! wait_counter_ge "${timeout_poll}" \ + $ns2 "MPTcpExtMPJoinSynTx" $((syn_tx + 1)); then + not_ready=3D"no subflow re-created before close" + fi + fi + # Block the other path too, so this data is never sent: only + # the close of the MPTCP socket can then stop the subflow being + # re-created. The initial subflow is no longer closed after a + # few retransmissions: that would close it too. + ip netns exec $ns2 sysctl -q net.ipv4.tcp_retries2=3D15 + if [ -z "${not_ready}" ] && ! nft_drop_from 10.0.1.2; then + not_ready=3D"unable to drop the packets" + fi + local fc_before + fc_before=3D$(fastclose_nr $ns2) + kill_client + chk_no_sf_connecting "${not_ready}" "${fc_before}" + mptcp_lib_kill_group_wait $tests_pid + kill_events_pids + + join_syn_tx=3D2 chk_join_nr 1 1 1 + chk_evt_nr ns2 MPTCP_LIB_EVENT_SUB_ESTABLISHED 1 + # the re-created subflow, closed with the MPTCP socket + chk_evt_nr ns2 MPTCP_LIB_EVENT_SUB_CLOSED 2 error 1 + sf_retry_cleanup + fi + + # the only subflow is not re-created + if reset_with_events "subflow retry, no other subflow" && + continue_if has_subflow_retries && init_nft_filter; then + sf_retry_init + pm_nl_flush_endpoint $ns2 + { timeout_test=3D600 test_linkfail=3D131072 \ + run_tests $ns1 $ns2 10.0.1.1 >/dev/null & } 2>/dev/null + local tests_pid=3D$! + + print_check "not re-created" + if ! wait_counter_ge $((timeout_poll * 4)) \ + $ns1 "MPTcpExtMPCapableACKRX" 1; then + fail_test "connection not established" + elif ! nft_drop_from 10.0.1.2; then + fail_test "unable to drop the packets" + elif ! wait_counter_ge "${timeout_poll}" \ + $ns2 "TcpExtTCPAbortOnTimeout" 1; then + fail_test "subflow not closed" + else + # the worker decides right after TCP closed the subflow + sleep 2 + local syn_tx + syn_tx=3D$(mptcp_lib_get_counter $ns2 \ + "MPTcpExtMPJoinSynTx") + if [ "${syn_tx}" !=3D 0 ]; then + fail_test "subflow re-created" + else + print_ok + fi + fi + mptcp_lib_kill_group_wait $tests_pid + kill_events_pids + + join_syn_tx=3D0 chk_join_nr 0 0 0 + chk_evt_nr ns2 MPTCP_LIB_EVENT_SUB_CLOSED 1 error 1 + sf_retry_cleanup + fi } =20 add_addr_timeout_tests() --=20 2.25.1