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[144.49.247.21]) by smtp-relay.gmail.com with ESMTPS id 006d021491bc7-696894ce108sm1159405eaf.16.2026.05.07.08.51.53 for (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Thu, 07 May 2026 08:51:53 -0700 (PDT) X-Relaying-Domain: broadcom.com X-CFilter-Loop: Reflected Received: by mail-qk1-f198.google.com with SMTP id af79cd13be357-8eab57f0e8bso27614085a.0 for ; Thu, 07 May 2026 08:51:53 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=broadcom.com; s=google; t=1778169113; x=1778773913; darn=vger.kernel.org; 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; bh=3Gej9rC0V5wj21YK/OT0tP6dMq4zLV0oZtuZHtg6JDU=; b=FVziDCaZt9A7Icol0tsQQITtIfwOK/o7xP5yLgiX2GJVx+0cqGOBw+GuDXuJGQJiPx yLRqm5IoYHFUSl/29gYTFci8pnlywIs463JIHfdb5x2n6OI313D+T26Qcy/Kt5XeCm1W XI+SffGrUPe3r470jHOz0HeKFKa+dRG0IgMTw= X-Forwarded-Encrypted: i=1; AFNElJ9roRGT5GVaHKZVnFBpNkKinods3ypi9dMf1rOvPJke2aQeK1BmjfJucfEVIUW7gKKvCBHNUdiHJBqNYw0=@vger.kernel.org X-Received: by 2002:a05:620a:3195:b0:8ea:c7a8:5065 with SMTP id af79cd13be357-904d4392205mr887325385a.2.1778169112802; Thu, 07 May 2026 08:51:52 -0700 (PDT) X-Received: by 2002:a05:620a:3195:b0:8ea:c7a8:5065 with SMTP id af79cd13be357-904d4392205mr887320985a.2.1778169112144; Thu, 07 May 2026 08:51:52 -0700 (PDT) Received: from photon-d7fac424c0d3 ([192.19.161.250]) by smtp.gmail.com with ESMTPSA id af79cd13be357-90642b76d39sm240711885a.2.2026.05.07.08.51.49 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 07 May 2026 08:51:51 -0700 (PDT) From: Ankit Jain To: edumazet@google.com, netdev@vger.kernel.org Cc: kuba@kernel.org, davem@davemloft.net, pabeni@redhat.com, ncardwell@google.com, kuniyu@google.com, horms@kernel.org, shuah@kernel.org, quic_subashab@quicinc.com, quic_stranche@quicinc.com, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, karen.badiryan@broadcom.com, ajay.kaher@broadcom.com, alexey.makhalov@broadcom.com, vamsi-krishna.brahmajosyula@broadcom.com, yin.ding@broadcom.com, tapas.kundu@broadcom.com, Ankit Jain Subject: [PATCH net v3 2/2] selftests/net: add packetdrill test for locked SO_RCVBUF SWS Date: Thu, 7 May 2026 15:48:06 +0000 Message-ID: <20260507154806.18635-3-ankit-aj.jain@broadcom.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260507154806.18635-1-ankit-aj.jain@broadcom.com> References: <20260507154806.18635-1-ankit-aj.jain@broadcom.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-DetectorID-Processed: b00c1d49-9d2e-4205-b15f-d015386d3d5e Add a packetdrill test to verify that locked SO_RCVBUF sockets do not suffer from scaling_ratio truesize penalties. The test uses a standard 1460 MSS and sends medium-sized packets (600, 700, 800 bytes) to trigger the recalculation logic. It checks that the internal window clamp (tcpi_rcv_ssthresh) does not drop unexpectedly. Signed-off-by: Ankit Jain --- .../net/packetdrill/tcp_locked_rcvbuf_sws.pkt | 29 +++++++++++++++++++ 1 file changed, 29 insertions(+) create mode 100644 tools/testing/selftests/net/packetdrill/tcp_locked_rcvbuf_sws.pkt diff --git a/tools/testing/selftests/net/packetdrill/tcp_locked_rcvbuf_sws.pkt b/tools/testing/selftests/net/packetdrill/tcp_locked_rcvbuf_sws.pkt new file mode 100644 index 000000000000..43e1d00d5f26 --- /dev/null +++ b/tools/testing/selftests/net/packetdrill/tcp_locked_rcvbuf_sws.pkt @@ -0,0 +1,29 @@ +// SPDX-License-Identifier: GPL-2.0 +// Test that TCP does not reduce scaling_ratio for locked SO_RCVBUF. + +0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3 ++0 setsockopt(3, SOL_SOCKET, SO_RCVBUF, [32768], 4) = 0 ++0 bind(3, ..., ...) = 0 ++0 listen(3, 1) = 0 + +// Establish connection with standard MSS. ++0 < S 0:0(0) win 65535 ++0 > S. 0:0(0) ack 1 <...> ++0 < . 1:1(0) ack 1 win 65535 ++0 accept(3, ..., ...) = 4 + +// Inject varying payload sizes to force scaling_ratio recalculation. ++0.1 < P. 1:601(600) ack 1 win 65535 ++0 > . 1:1(0) ack 601 <...> + ++0.1 < P. 601:1301(700) ack 1 win 65535 ++0 > . 1:1(0) ack 1301 <...> + ++0.1 < P. 1301:2101(800) ack 1 win 65535 ++0 > . 1:1(0) ack 2101 <...> + +// Check that truesize penalty did not reduce the window clamp. +// On unpatched kernels, rcv_ssthresh drops to ~22K. ++0.1 %{ +assert tcpi_rcv_ssthresh > 28000, f"rcv_ssthresh dropped unexpectedly: {tcpi_rcv_ssthresh}" +}% -- 2.53.0