From mboxrd@z Thu Jan 1 00:00:00 1970 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 25CB32AD04; Tue, 26 Aug 2025 13:38:11 +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=1756215491; cv=none; b=RgedlMSQQ7URR2fP5bIe4QhsHpr2PXPdzhtXnIY6LqdMASN0SzyNDZZpRtPXTSsYUl8xeUqMzs6bzMbuA5D9UhFIEqB1ZvD9Ib0d7I9Y+1rZdoeluXzjUm9oPY1+hIQFM9gvxqElm0aMUGFI6a3Pf28gbqryJo2lOf06shCQDms= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756215491; c=relaxed/simple; bh=QlmBmNAeA6HbBGhR2V3qV13SQUE/3JDVmqg7VnG1kjE=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=odw7k7yzYOcZfhoq3LNa0eG9Fwf/YC4hO/JG0ra0K89V4yyDnCbTcqIM3UWBKuVmTN0xUhx9W3NAIk/+19WrYOH54JentvE6SXLCqrFg2ZrxCSgoq3Y7kPUSZ7K4DL3r5nViovAemkTxmYu5+o3ifk730pT17Z2wM+g7hDa6lkM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=aAQlaCTm; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="aAQlaCTm" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A2719C4CEF1; Tue, 26 Aug 2025 13:38:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1756215491; bh=QlmBmNAeA6HbBGhR2V3qV13SQUE/3JDVmqg7VnG1kjE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=aAQlaCTmRuSnFHqkl3JdZdG07HHKwyYkDIxy5uh4VmAWFVF90cS9IncSdc7TEWWTN XqkGsjcy9xLwJkx9xmOAOkTCyxJdUO9UiHUZ3ZdrG9ewej75L2WwEq5N+wzHNylxpq xfzAbNL7o9cOKPPbr5ziOuFabjWqasiAftnrRlBI= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Christoph Paasch , Tariq Toukan , Gal Pressman , Jakub Kicinski , Sasha Levin Subject: [PATCH 5.15 053/644] net/mlx5: Correctly set gso_size when LRO is used Date: Tue, 26 Aug 2025 13:02:24 +0200 Message-ID: <20250826110947.816039776@linuxfoundation.org> X-Mailer: git-send-email 2.50.1 In-Reply-To: <20250826110946.507083938@linuxfoundation.org> References: <20250826110946.507083938@linuxfoundation.org> User-Agent: quilt/0.68 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Christoph Paasch [ Upstream commit 531d0d32de3e1b6b77a87bd37de0c2c6e17b496a ] gso_size is expected by the networking stack to be the size of the payload (thus, not including ethernet/IP/TCP-headers). However, cqe_bcnt is the full sized frame (including the headers). Dividing cqe_bcnt by lro_num_seg will then give incorrect results. For example, running a bpftrace higher up in the TCP-stack (tcp_event_data_recv), we commonly have gso_size set to 1450 or 1451 even though in reality the payload was only 1448 bytes. This can have unintended consequences: - In tcp_measure_rcv_mss() len will be for example 1450, but. rcv_mss will be 1448 (because tp->advmss is 1448). Thus, we will always recompute scaling_ratio each time an LRO-packet is received. - In tcp_gro_receive(), it will interfere with the decision whether or not to flush and thus potentially result in less gro'ed packets. So, we need to discount the protocol headers from cqe_bcnt so we can actually divide the payload by lro_num_seg to get the real gso_size. v2: - Use "(unsigned char *)tcp + tcp->doff * 4 - skb->data)" to compute header-len (Tariq Toukan ) - Improve commit-message (Gal Pressman ) Fixes: e586b3b0baee ("net/mlx5: Ethernet Datapath files") Signed-off-by: Christoph Paasch Reviewed-by: Tariq Toukan Reviewed-by: Gal Pressman Link: https://patch.msgid.link/20250715-cpaasch-pf-925-investigate-incorrect-gso_size-on-cx-7-nic-v2-1-e06c3475f3ac@openai.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- drivers/net/ethernet/mellanox/mlx5/core/en_rx.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c b/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c index d2de1e6c514c1..2f6d3473bcbf1 100644 --- a/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c +++ b/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c @@ -788,8 +788,9 @@ static void mlx5e_lro_update_tcp_hdr(struct mlx5_cqe64 *cqe, struct tcphdr *tcp) } } -static void mlx5e_lro_update_hdr(struct sk_buff *skb, struct mlx5_cqe64 *cqe, - u32 cqe_bcnt) +static unsigned int mlx5e_lro_update_hdr(struct sk_buff *skb, + struct mlx5_cqe64 *cqe, + u32 cqe_bcnt) { struct ethhdr *eth = (struct ethhdr *)(skb->data); struct tcphdr *tcp; @@ -840,6 +841,8 @@ static void mlx5e_lro_update_hdr(struct sk_buff *skb, struct mlx5_cqe64 *cqe, tcp->check = csum_ipv6_magic(&ipv6->saddr, &ipv6->daddr, payload_len, IPPROTO_TCP, check); } + + return (unsigned int)((unsigned char *)tcp + tcp->doff * 4 - skb->data); } static inline void mlx5e_skb_set_hash(struct mlx5_cqe64 *cqe, @@ -1055,8 +1058,9 @@ static inline void mlx5e_build_rx_skb(struct mlx5_cqe64 *cqe, mlx5e_ipsec_offload_handle_rx_skb(netdev, skb, cqe); if (lro_num_seg > 1) { - mlx5e_lro_update_hdr(skb, cqe, cqe_bcnt); - skb_shinfo(skb)->gso_size = DIV_ROUND_UP(cqe_bcnt, lro_num_seg); + unsigned int hdrlen = mlx5e_lro_update_hdr(skb, cqe, cqe_bcnt); + + skb_shinfo(skb)->gso_size = DIV_ROUND_UP(cqe_bcnt - hdrlen, lro_num_seg); /* Subtract one since we already counted this as one * "regular" packet in mlx5e_complete_rx_cqe() */ -- 2.39.5