From nobody Tue Apr 7 16:18:45 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 9A5FD36EAB7; Thu, 26 Feb 2026 00:49:26 +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=1772066966; cv=none; b=K7vva8/pA1H6aWMMVyZraU+KLbarcEM7A+weSM2/YI251Qwvm8tgWnBPv/zfhT1b86OehdBfSHl99GUjNx5hcsX0tBrC43KJTrEDiC1ASXEkWYRMFfqFp2NYP2FwW0vx9QNtKfsIrlWkGuQD6SWPLKYA4luuxDUn6a1KMVtYdXo= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772066966; c=relaxed/simple; bh=emTIU1TaBbIx/tDTZhzmiIjXQ7JpqWXdQa8oeCKbuEQ=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=QUOdviRMvR8M0MRf/VfwpquKrAVFQ29RLTkMpzrB8JHh/0hfHL1DFlKKfkOKbrGNZm36J/wCzqB9Jo98w2a00n8Gen8SgFd3qdn/p96Ppe75Mp31ICD/+5c5c8X0y6fW6Xh/pY73grWdr7p+cB63M96f0a4vSaIL35M/hktCyvc= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=vGfuIYgx; 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="vGfuIYgx" Received: by smtp.kernel.org (Postfix) with ESMTPS id 7AEDEC2BCB3; Thu, 26 Feb 2026 00:49:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1772066966; bh=emTIU1TaBbIx/tDTZhzmiIjXQ7JpqWXdQa8oeCKbuEQ=; h=From:Date:Subject:References:In-Reply-To:To:Cc:Reply-To:From; b=vGfuIYgx4DoBb5f4vSs6mOxQudTIUHweAho9Fjkungb1qds1LyZ/TtP0w+DRtkOPO qWVZVKWJGFPopemycgKK0bm0HSKZynQoDvXNSA+gtXN5Ban/cfPfB/nk3T2oB1wivU Mh+82R1x0kjroVe6fUU7ZZDYQpgEirUNd1ZTacwzNCfv/pxbxQQPgy+PI8G2/1b3N9 fXfk4Ulji99zlWN+gRDpNOJO11p1oOsC0ZT3drX97zFBplLzDyt3snZL5/R6y7IhZ8 S5Iq9UF7tHmTtKd0aVxGfyA3ZdQcs5qBNXHtqjJRnV1lYjRzbLAWGqzyvaCJOaaPhc vqPiPJv8uVv1A== 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 70737FD45FE; Thu, 26 Feb 2026 00:49:26 +0000 (UTC) From: Simon Baatz via B4 Relay Date: Thu, 26 Feb 2026 01:49:11 +0100 Subject: [PATCH RFC net-next v2 5/5] selftests/net: packetdrill: add tcp_rcv_neg_window.pkt Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20260226-tcp_rfc7323_retract_wnd_rfc-v2-5-aa3f8f9cc639@gmail.com> References: <20260226-tcp_rfc7323_retract_wnd_rfc-v2-0-aa3f8f9cc639@gmail.com> In-Reply-To: <20260226-tcp_rfc7323_retract_wnd_rfc-v2-0-aa3f8f9cc639@gmail.com> To: Eric Dumazet , Neal Cardwell , Kuniyuki Iwashima , "David S. Miller" , Jakub Kicinski , Paolo Abeni , Simon Horman , Jonathan Corbet , Shuah Khan , David Ahern , Stefano Brivio , Jon Maloy , Jason Xing , mfreemon@cloudflare.com, Shuah Khan , Stefano Brivio Cc: Christian Ebner , netdev@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, Simon Baatz X-Mailer: b4 0.14.2 X-Developer-Signature: v=1; a=ed25519-sha256; t=1772066964; l=1560; i=gmbnomis@gmail.com; s=20260220; h=from:subject:message-id; bh=/JWWw4Fx6ONTjfm9hTqMNguk1B74iLUSkQSY5L1syFw=; b=qtBvPU3M3B3V/VgUAmVlVHh3U9olqOaO8RlGMGMq/jDkZ3NJb8DN2fmTUTuAv9N6vkBm7o8Zl i1rmFiNfQTYBQ+Kkkk6LDQbUeM7RXN9h3C3Mwq9qcT33KON9ik/bgHf 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 --- .../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