From nobody Sun Mar 22 10:12:49 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id DB66536B075; Mon, 9 Mar 2026 08:03:46 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773043427; cv=none; b=QcnTcbRjuLLr8A2Id4szHFnDwORwcLoLC2zNq0BWOfaeY88n9P2QGZ7w70AuCIkGA7JkqzE4yx/y2cJiYwTRoZX1/cD23RyfaMJ8d/d8mkD4YSklxJBUCoXbMuAutMy9b8NUBjB7GpG4dziOhjzncGrGW8J0zS/QsUhOUvCDPo8= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773043427; c=relaxed/simple; bh=emTIU1TaBbIx/tDTZhzmiIjXQ7JpqWXdQa8oeCKbuEQ=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=aHk5yrEehq+l1hFrEqVteW1YDhvggGdj1JV2kxClgxkhrrQQ+Uy0bxUHBnK+EnOkgXT4yM3WTskgYJR/eU5/ZQJ9Bc8M0sHwC/ogOnN67mW1+2RZuHCweEzJ7JjQw3PgIYoyZGde0kOcxG2FWhY+z+e4Iu9Cm1vNV2MyafW7fGg= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=oHylr5Sr; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="oHylr5Sr" Received: by smtp.kernel.org (Postfix) with ESMTPS id AB3B9C2BCB6; Mon, 9 Mar 2026 08:03:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1773043426; bh=emTIU1TaBbIx/tDTZhzmiIjXQ7JpqWXdQa8oeCKbuEQ=; h=From:Date:Subject:References:In-Reply-To:To:Cc:Reply-To:From; b=oHylr5SrJEEJoOjUUMs9zV6AckkonQRN0XrGTbbHE83Da7QroQPZaES3D+Z5aZ2N8 3usNEzeJuI7aoNsGkKob0GnInh4jvA4pkGJjMA6y+NKBBeYvZOD5Pg6AZEnNnGmPKK XSdEFvXZ0lsm0hV7vxWkfXUvVfqCGEGio3Nla9LhPhbINCYNbLpKRVD/zHwCQoiWEA 5+iuEjOaHRvI2u1Zd4zlyDIERUdoupdeBJX1uCOPDa0HfU1Q+Wr1Vs9Brtb+zewo4b nQIWLYM4duf1ofqydrzmjchMYOh7qxgWJMi6A7iritfagvFJ/kNSROhrJmMETEEI8T uoqHbwT2velXw== Received: from aws-us-west-2-korg-lkml-1.web.codeaurora.org (localhost.localdomain [127.0.0.1]) by smtp.lore.kernel.org (Postfix) with ESMTP id A1F02EF3709; Mon, 9 Mar 2026 08:03:46 +0000 (UTC) From: Simon Baatz via B4 Relay Date: Mon, 09 Mar 2026 09:02:31 +0100 Subject: [PATCH net-next v3 6/6] selftests/net: packetdrill: add tcp_rcv_neg_window.pkt Precedence: bulk X-Mailing-List: mptcp@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20260309-tcp_rfc7323_retract_wnd_rfc-v3-6-4c7f96b1ec69@gmail.com> References: <20260309-tcp_rfc7323_retract_wnd_rfc-v3-0-4c7f96b1ec69@gmail.com> In-Reply-To: <20260309-tcp_rfc7323_retract_wnd_rfc-v3-0-4c7f96b1ec69@gmail.com> To: Eric Dumazet , Neal Cardwell , Kuniyuki Iwashima , "David S. Miller" , Jakub Kicinski , Paolo Abeni , Simon Horman , Jonathan Corbet , Shuah Khan , David Ahern , Jon Maloy , Jason Xing , mfreemon@cloudflare.com, Shuah Khan , Stefano Brivio , Matthieu Baerts , Mat Martineau , Geliang Tang Cc: netdev@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, mptcp@lists.linux.dev, Simon Baatz X-Mailer: b4 0.14.2 X-Developer-Signature: v=1; a=ed25519-sha256; t=1773043425; l=1560; i=gmbnomis@gmail.com; s=20260220; h=from:subject:message-id; bh=/JWWw4Fx6ONTjfm9hTqMNguk1B74iLUSkQSY5L1syFw=; b=2D7v4mt8UrAsF6NRbarJgDDGMJrIAAIk6UGHgHlbR6lGUYUnBAQbYbj1gZaxxGqnn6xPfh8YQ y5j57Qjr1c9BLHK8/b0/n69p50Qeg1agzXfds2tVH6K9S9xPkL77w9u X-Developer-Key: i=gmbnomis@gmail.com; a=ed25519; pk=T/JIz/6F5bf1uQJr69lmyi7czVG+F9TVZ/8x5z9Wtqw= X-Endpoint-Received: by B4 Relay for gmbnomis@gmail.com/20260220 with auth_id=641 X-Original-From: Simon Baatz Reply-To: gmbnomis@gmail.com From: Simon Baatz The test ensures we correctly apply the maximum advertised window limit when rcv_nxt advances past rcv_mwnd_seq, so that the "usable window" is properly clamped to zero rather than becoming negative. Signed-off-by: Simon Baatz Reviewed-by: Eric Dumazet --- .../net/packetdrill/tcp_rcv_neg_window.pkt | 26 ++++++++++++++++++= ++++ 1 file changed, 26 insertions(+) diff --git a/tools/testing/selftests/net/packetdrill/tcp_rcv_neg_window.pkt= b/tools/testing/selftests/net/packetdrill/tcp_rcv_neg_window.pkt new file mode 100644 index 0000000000000000000000000000000000000000..15a9b4938f16d175ac54f3fd192= ed2b59b0a4399 --- /dev/null +++ b/tools/testing/selftests/net/packetdrill/tcp_rcv_neg_window.pkt @@ -0,0 +1,26 @@ +// SPDX-License-Identifier: GPL-2.0 + +--mss=3D1000 + +`./defaults.sh` + +// Establish a connection. + +0 socket(..., SOCK_STREAM, IPPROTO_TCP) =3D 3 + +0 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) =3D 0 + +0 setsockopt(3, SOL_SOCKET, SO_RCVBUF, [20000], 4) =3D 0 + +0 bind(3, ..., ...) =3D 0 + +0 listen(3, 1) =3D 0 + + +0 < S 0:0(0) win 32792 + +0 > S. 0:0(0) ack 1 win 18980 + +.1 < . 1:1(0) ack 1 win 257 + + +0 accept(3, ..., ...) =3D 4 + +// A too big packet is accepted if the receive queue is empty + +0 < P. 1:20001(20000) ack 1 win 257 +// Send a RST immediately so that there is no rcv_wup/rcv_mwnd_seq update = yet + +0 < R. 20001:20001(0) ack 1 win 257 + + +.1 %{ assert tcpi_state =3D=3D TCP_CLOSE, tcpi_state }% + --=20 2.53.0