From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from fout-a5-smtp.messagingengine.com (fout-a5-smtp.messagingengine.com [103.168.172.148]) (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 6DFD542314A for ; Fri, 10 Jul 2026 13:43:16 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=103.168.172.148 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783690998; cv=none; b=lJ7WYbHCn+8FG67rcc1gSFQ37WM/RtxTpaqQvyATliLasudAcYoaUBT4n+vZuX3dJtiSshVp5RqQi/eK3rhWCoC5g+KKoEX6+ujORsWmDoTpFFcm12ZVRNkYPTNMH6rnNuGzH5MsCqt+wPRWWifOEaeUCaFUYaIDsCn3h9GR7sE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783690998; c=relaxed/simple; bh=ZWXbgafIGTz8xu/L99Wf9gJbdEsf4Q7FwDvYQks5ALo=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=ro5WIMpoxOSG9Ga6wVWjEgoPt3l23n7Qgg21el+2Jk/h31gVMzKIxYC3F6M8jpgrDJQM1tIJPXFp//G1pO6Lr4OPEWXHg9cbcUvdfvkf9rS97+bM84immF7aUkSoJ9b9P9dfzWuxjFBmkgtghTp3gzzzstQn6g+n1nhiX7cX9XY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=fastmail.im; spf=pass smtp.mailfrom=fastmail.im; dkim=pass (2048-bit key) header.d=fastmail.im header.i=@fastmail.im header.b=sKAuGd4s; dkim=pass (2048-bit key) header.d=messagingengine.com header.i=@messagingengine.com header.b=Q9YdPoFY; arc=none smtp.client-ip=103.168.172.148 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=fastmail.im Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=fastmail.im Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=fastmail.im header.i=@fastmail.im header.b="sKAuGd4s"; dkim=pass (2048-bit key) header.d=messagingengine.com header.i=@messagingengine.com header.b="Q9YdPoFY" Received: from phl-compute-11.internal (phl-compute-11.internal [10.202.2.51]) by mailfout.phl.internal (Postfix) with ESMTP id 9B82FEC01CF; Fri, 10 Jul 2026 09:43:15 -0400 (EDT) Received: from phl-frontend-04 ([10.202.2.163]) by phl-compute-11.internal (MEProxy); Fri, 10 Jul 2026 09:43:15 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fastmail.im; h= cc:cc:content-transfer-encoding:content-type:date:date:from:from :in-reply-to:in-reply-to:message-id:mime-version:references :reply-to:subject:subject:to:to; s=fm2; t=1783690995; x= 1783777395; bh=NBxc7NjrXRB/RPnGvxFt2oPvmnXmDKIQnsk0vpD0Uls=; b=s KAuGd4sUaz0INHHQfOSAW8f/VF/uVFU69BN0xdKk7xt/3mNPLXRsuRepEmfBxLTW 0NgBeYIHo7Yw7RipPyz+QHDjM/YXzE55WhvK1g5oPBAtB+cfa5dtu0No3HLBNQB/ V8wD1aOOwTsd6seZc8vN0aAyFUrxwtY/2LA9kv2dg19Ho6gophfmfJJIuV/14lKi edxnRVpL9j4g3w6YMwPZhu2KaO/W2mJivUa5t/SAEbXhDDZ0kgE01pQ5GOEY5Xgg cI7l5Xsnh5A3Wx6CibhcQ9HgjJ62rQhyMYa8EHqzG6W0yDhJ0BKeEef0NB5z4Vds uFu5SAsesuacFeaCySCoA== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:cc:content-transfer-encoding :content-type:date:date:feedback-id:feedback-id:from:from :in-reply-to:in-reply-to:message-id:mime-version:references :reply-to:subject:subject:to:to:x-me-proxy:x-me-sender :x-me-sender:x-sasl-enc; s=fm2; t=1783690995; x=1783777395; bh=N Bxc7NjrXRB/RPnGvxFt2oPvmnXmDKIQnsk0vpD0Uls=; b=Q9YdPoFYbfyIjvX85 nqOz5DBTIh+6XCpAtZInuG9QTO9tY7PkTkyHtHgKrLhcOuD3aKsfVAAteQUCFTFf ewYIBSxMjx+Gb0KOiHB6Wdz3vst0hq7QwaPmVOsSfaMoop8QK+hcpqCSzDR7M8Cs 3ticLRDTaOTh8dxGNx6ECGkJmFk70GgITPM6VcBhkl2saPviRzRTvvOU0uF6Qbue 0kkVIS8cCA4+XD7hujfp6FA9J5BS44ZH8+FVxx+001aktYBvOAiKngaUSSndqezl f4/vTzyg+eTgT9AeNoik0nbIXt67bOdmcrbS+PbjLclnHzUw3yzNgnMYYnTE5wC3 gJmUQ== X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: dmFkZTEVFm+PuK8xnTILKnn5BF1WxaOh1NU1c4AWOm+trf7xjxbQVV4Wu/mS84/kbRtIXv 7rHAtBm8CHEeyrv3AsvyWdvto1dUnam/9BY2K8TY5q7X5K2DLmOFYOafye9ypBbvvbsE/Y 815j+wouQNbeSKb3fj6Pco6dtynN3Wvj9n+G+FKepS7CNrrV2iLZ0WRdH5ag3dhpPbRrb2 td8lEMoy9cSYyuzqoACjgQGsVGYmmaE3Vmtt8eTDN6qfQBKrMdgGRpw/x85PmzwpyRyFOg fIowvgp/DdcSXxlmG59lbYPsvBRkbElKhM4RsIaBQr5y9owK5Q+nJxV04NvIuJZ6UxdcYV xHF09XiyBc/t35M3vf0pvi5DYn/UQnnn1mmzg2siY7jxcaXxGJ4d8PZuGRTddbfmfPx7Kj vCA3z1IsDKhYMmQaiZf5Vi7DUagXZc5CMR19vUNgGjRKJkvwcXpvQ5CTj/IJ3zdPYrAwvu GJfYzWBf/8gmFp9I48DDsBeOFKS/kKJFntLzG/84haCqn2oQ4PHa4hzklzjER3F/uQRJ2E Hl+D+CEHokomq9UowM8kCfZr9sdj9zBfDCU5iXourjh9SWgYHuqKQdhgpldwXDSRd2wvTX x7hk3JjmlGN4neFkQ2iJgF586wLKEb7/YPfQOt5c8SWT4IwdSoPSSMRBtsqQ X-ME-Proxy: Feedback-ID: i559e4809:Fastmail Received: by mail.messagingengine.com (Postfix) with ESMTPA; Fri, 10 Jul 2026 09:43:14 -0400 (EDT) From: Alice Mikityanska To: Daniel Borkmann , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Xin Long , Willem de Bruijn , Willem de Bruijn , David Ahern , Nikolay Aleksandrov Cc: Shuah Khan , Stanislav Fomichev , Andrew Lunn , Simon Horman , Florian Westphal , netdev@vger.kernel.org, Alice Mikityanska Subject: [PATCH net-next v9 2/9] net: Enable BIG TCP with partial GSO Date: Fri, 10 Jul 2026 16:42:35 +0300 Message-ID: <20260710134242.216538-3-alice.kernel@fastmail.im> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260710134242.216538-1-alice.kernel@fastmail.im> References: <20260710134242.216538-1-alice.kernel@fastmail.im> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Alice Mikityanska skb_segment is called for partial GSO, when netif_needs_gso returns true in validate_xmit_skb. Partial GSO is needed, for example, when segmentation of tunneled traffic is offloaded to a NIC that only supports inner checksum offload. Currently, skb_segment clamps the segment length to 65534 bytes, because gso_size == 65535 is a special value GSO_BY_FRAGS, and we don't want to accidentally assign mss = 65535, as it would fall into the GSO_BY_FRAGS check further in the function. This implementation, however, artificially blocks len > 65534, which is possible since the introduction of BIG TCP. To allow bigger lengths and avoid resegmentation of BIG TCP packets, store the gso_by_frags flag in the beginning and don't use a special value of mss for this purpose after mss was modified. Signed-off-by: Alice Mikityanska Reviewed-by: Willem de Bruijn --- net/core/skbuff.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/net/core/skbuff.c b/net/core/skbuff.c index 18dabb4e9cfa..6ae4c2b205f2 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -4775,6 +4775,7 @@ struct sk_buff *skb_segment(struct sk_buff *head_skb, struct sk_buff *tail = NULL; struct sk_buff *list_skb = skb_shinfo(head_skb)->frag_list; unsigned int mss = skb_shinfo(head_skb)->gso_size; + bool gso_by_frags = mss == GSO_BY_FRAGS; unsigned int doffset = head_skb->data - skb_mac_header(head_skb); unsigned int offset = doffset; unsigned int tnl_hlen = skb_tnl_header_len(head_skb); @@ -4790,7 +4791,7 @@ struct sk_buff *skb_segment(struct sk_buff *head_skb, int nfrags, pos; if ((skb_shinfo(head_skb)->gso_type & SKB_GSO_DODGY) && - mss != GSO_BY_FRAGS && mss != skb_headlen(head_skb)) { + !gso_by_frags && mss != skb_headlen(head_skb)) { struct sk_buff *check_skb; for (check_skb = list_skb; check_skb; check_skb = check_skb->next) { @@ -4818,7 +4819,7 @@ struct sk_buff *skb_segment(struct sk_buff *head_skb, sg = !!(features & NETIF_F_SG); csum = !!can_checksum_protocol(features, proto); - if (sg && csum && (mss != GSO_BY_FRAGS)) { + if (sg && csum && !gso_by_frags) { if (!(features & NETIF_F_GSO_PARTIAL)) { struct sk_buff *iter; unsigned int frag_len; @@ -4852,9 +4853,8 @@ struct sk_buff *skb_segment(struct sk_buff *head_skb, /* GSO partial only requires that we trim off any excess that * doesn't fit into an MSS sized block, so take care of that * now. - * Cap len to not accidentally hit GSO_BY_FRAGS. */ - partial_segs = min(len, GSO_BY_FRAGS - 1) / mss; + partial_segs = len / mss; if (partial_segs > 1) mss *= partial_segs; else @@ -4878,7 +4878,7 @@ struct sk_buff *skb_segment(struct sk_buff *head_skb, int hsize; int size; - if (unlikely(mss == GSO_BY_FRAGS)) { + if (unlikely(gso_by_frags)) { len = list_skb->len; } else { len = head_skb->len - offset; -- 2.54.0