From nobody Sun Mar 22 10:12:44 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 D9E8936B074; 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=1773043426; cv=none; b=QWzOP1ei5PPCrec4JbGBq0KD1Wxj2nd3PDkqeNxL67Ev6kPWsp7CoKQ6Z0w398Ai47gAe9DULMrk4KOWIwgozAiTRwSZrGjIidMLiRGoLVo6z+6vBu3Qx0aPrAMNqLO5dU3csUjOvxrLClWQOdGfZ2hnZJAVsP5++XAk5LgEdrc= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773043426; c=relaxed/simple; bh=wm3+FPgt/onbzQ/osNpSD8KFc26/gyxoBmdvkSWqouY=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=hOZpGf1HktQ56tFy5seW1FUJoQachqE7wYOd83xrk1eoTJug7Kx0DHCzWlj7EMIykFzemRNDars1X/R7j6BmhflJDjc7su1IxVPKIgZcIh54bAVi0dDKyHizi/3bsFgeoDPgduUHO7BygahDex5D2oyXlNLvnvbmsjQcg5ED7IQ= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=ts9DMZy9; 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="ts9DMZy9" Received: by smtp.kernel.org (Postfix) with ESMTPS id 9B412C2BCB2; 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=wm3+FPgt/onbzQ/osNpSD8KFc26/gyxoBmdvkSWqouY=; h=From:Date:Subject:References:In-Reply-To:To:Cc:Reply-To:From; b=ts9DMZy9wNVrpbIARzo1Yeqcfd3twYqEa09HQ8z/6Ny8+FUTZTSZ/k740vX1Brf8L U0NXv6Qq0gMGt7g5P39nDciJvLZUt5IoJClBfG7F3Z2RE3S/AG7WV9c1nzISIJ+LvZ O0w5lAD7TIgEIw3YjgSeyoxmociN2dGZto6qFScxN/utozOp6NcP5xyPALR8lxVBW4 CvJ/zY7jSD+vCaj+OwEueEJB3ezV/EyQw5lOhxKMdk4luDMNVn5igsAvTcb+277uAH 1Tf2aJgtW0Awinx/GXzaQ0VRLpPToF8G5n8yYwf+/Rk/sfqUiHDl0JdGmJqGr+XxYI Qy8ATBFUB5i3A== 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 92632EF36FB; Mon, 9 Mar 2026 08:03:46 +0000 (UTC) From: Simon Baatz via B4 Relay Date: Mon, 09 Mar 2026 09:02:30 +0100 Subject: [PATCH net-next v3 5/6] selftests/net: packetdrill: add tcp_rcv_wnd_shrink_allowed.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-v3-5-4c7f96b1ec69@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=1920; i=gmbnomis@gmail.com; s=20260220; h=from:subject:message-id; bh=arhqPRPG3bbk8HOp2tIbu0W9lKz7uQEcs1MV+6YcVmE=; b=6U+j8jI9mgxnmmfYsnaaiZNjL8QRLggJ1951sCepfaA2tkHuxov6XCT4OHnCKQWsWXDnqejCy +lRkxVzNpKNCPod8a/Qokehmuhh9tjMcUe9QmnSmEI2sAX04fEQMQU8 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 This test verifies the sequence number checks using the maximum advertised window sequence number when net.ipv4.tcp_shrink_window is enabled. Signed-off-by: Simon Baatz Reviewed-by: Eric Dumazet --- .../net/packetdrill/tcp_rcv_wnd_shrink_allowed.pkt | 40 ++++++++++++++++++= ++++ 1 file changed, 40 insertions(+) diff --git a/tools/testing/selftests/net/packetdrill/tcp_rcv_wnd_shrink_all= owed.pkt b/tools/testing/selftests/net/packetdrill/tcp_rcv_wnd_shrink_allow= ed.pkt new file mode 100644 index 0000000000000000000000000000000000000000..6af0e0eb183a0d2fa474c304d96= 9ce6ddeb2a1e1 --- /dev/null +++ b/tools/testing/selftests/net/packetdrill/tcp_rcv_wnd_shrink_allowed.pkt @@ -0,0 +1,40 @@ +// SPDX-License-Identifier: GPL-2.0 + +--mss=3D1000 + +`./defaults.sh +sysctl -q net.ipv4.tcp_shrink_window=3D1 +sysctl -q net.ipv4.tcp_rmem=3D"4096 32768 $((32*1024*1024))"` + + 0 `nstat -n` + +// Establish a connection. + +0 socket(..., SOCK_STREAM, IPPROTO_TCP) =3D 3 + +0 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 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 + +0 < . 1:1(0) ack 1 win 257 + + +0 accept(3, ..., ...) =3D 4 + + +0 < P. 1:10001(10000) ack 1 win 257 + * > . 1:1(0) ack 10001 win 15 + + +0 < P. 10001:11024(1023) ack 1 win 257 + * > . 1:1(0) ack 11024 win 13 + +// Max window seq advertised 10001 + 15*1024 =3D 25361, last advertised: 1= 1024 + 13*1024 =3D 24336 + +// Segment beyond the max window is dropped + +0 < P. 11024:25362(14338) ack 1 win 257 + * > . 1:1(0) ack 11024 win 13 + +// Segment using the max window is accepted + +0 < P. 11024:25361(14337) ack 1 win 257 + * > . 1:1(0) ack 25361 win 0 + +// Check LINUX_MIB_BEYOND_WINDOW has been incremented once + +0 `nstat | grep TcpExtBeyondWindow | grep -q " 1 "` --=20 2.53.0