From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from fhigh-b1-smtp.messagingengine.com (fhigh-b1-smtp.messagingengine.com [202.12.124.152]) (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 45A653D170B for ; Tue, 2 Jun 2026 09:40:52 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=202.12.124.152 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780393253; cv=none; b=X2TAKJWITIemmcW1N+YFIaZj3bEf8MvMuclF0aW8izESg9r9qUdSlrKCT4Twt1K426/KIYKmUbsAGQb88gjIyD/ix04v3044p/Cwp5dbCWzLQeyzV0n/ChjIWzKFSYHXXLQ6mdBXK+6CM5a5QvDRxHuaGPRxKJH8tWnwDKF05GQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780393253; c=relaxed/simple; bh=xR+lpHEYhtSalS7ICtySUfJ89tlJPbulv8NkQMSaVTM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=C97gzxmC45Fog0GEgdQFMDWRkMwg0tgleXRringIgfnHF8t2CJzGrBwI8u4sGfCrUixJJ12PADI8xaXr0GjenZk03xwDAyd6myvtHmfj2OKBrNjfAIhl6j40P0f7IWbK8DUGxH1kxvCZiWJFcTHM/ZE/D6zKriE/1/vw5ogWRDk= 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=PBpOKY3z; dkim=pass (2048-bit key) header.d=messagingengine.com header.i=@messagingengine.com header.b=Cpsy+oqk; arc=none smtp.client-ip=202.12.124.152 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="PBpOKY3z"; dkim=pass (2048-bit key) header.d=messagingengine.com header.i=@messagingengine.com header.b="Cpsy+oqk" Received: from phl-compute-01.internal (phl-compute-01.internal [10.202.2.41]) by mailfhigh.stl.internal (Postfix) with ESMTP id 53E617A0066; Tue, 2 Jun 2026 05:40:51 -0400 (EDT) Received: from phl-frontend-03 ([10.202.2.162]) by phl-compute-01.internal (MEProxy); Tue, 02 Jun 2026 05:40:51 -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=fm1; t=1780393251; x= 1780479651; bh=FLnLn176gGjNiUkZRbkuZMuKaZ1ayJMKeizMGBpsEyY=; b=P BpOKY3zl5C720LgSOvSqalAwTKn2RO40LWuM90x7bCnquJNiURPV0PPOiXWtdI/c ITR3X+w/vd+aqVl3YikRImcS84xjgprK/FSVlgi+ZGfSThBhA9WgEq5mV6FyEPuH tUg0eWfoQNPGzjNM9C2FdWlbnQsgpR6lA2GkyushXZAt30evAbqIZZLZsuSDKZ/o BARTF7JzJ9HYUbml7cm3JwYiql5DiHGuXqJ3KUje76UH5pkST1JbW0W43EGGWykJ uvWaewLSPz1IFOUPdRG78rcgKO1B65lDJ0ROi/LvGl+QDuydZe1qEynE03g+zzOO hIpGchoMD3ZZXXFM3HdNA== 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=fm1; t=1780393251; x=1780479651; bh=F LnLn176gGjNiUkZRbkuZMuKaZ1ayJMKeizMGBpsEyY=; b=Cpsy+oqkw9Mj8v2Ub oLpON+09bZH5R+Wj9HKTcdaiU2FIhO5P/GnpyiMv1Ri5gwulBUPDlp85Tg9O+Imi TZTweYA0AhQfg+E2W/EbXQmAoCt4n+GgrGY44dArgw2cg8jlmP0Dt+jh5LPHM+bo eLKRfYmvhSsMfr/lPvKEq3N2yro1jY1T9nPn5M8QtHj7tgoSLaTJ3pmsgF71zAei mpLi6dYPoQ+Fvc5kPseg/ayx2JbO0YKj2z6sIu71sG3t3gnqldkQYmAFxkcYolGL A8vUt0W71hntbxgb2q+ofU9SVLts1UCKFWgZq6iaiKuaeJWld5Rkdlp1XqhELWH6 cRPvg== X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: dmFkZTE9tBEANdqxv95NqhdHHdXhj1o4AkdIVzwb8jjM1HqleHqSgAphWGPVWdofWa5NaJ ER1+bdTKu4iuMySGow/dR0s0eFoVOC/6dTzun6tkdzaeOOWbtEG06zBndcZtwjRhyaEqpS LIdhK0NEaayYQ6YzxQmC4sX50yKzwArmaEuiPOivokZV1AkyAlAc9SSPgZ1GnEgo3o6dDk bEn0w3Mqi9k2vnkZorhnXwd9uFf0d2PQPwaZiDxl+oi2Y7rHQyMVhjEWYHKl6/Ux+ouroe m5aDk5b3HiFHY/885fmPi0ztz+42JdSIp35bNIg/uJarg5ZvUClTXutfFP+vZJrYnhYFNS XyAxYLhoPk785Y/lXBU6cj8EhjMLfCrNHAgX7CaRb1DeZS8Z2cr+NZGUOFxun4CyUYyntF r0zcvFgN47J4OTe3BYkcoz/5hDMrdLLX+il2gBieV15JDsSjKDIz6COEBsOobTSq7JtLp5 bftuod8HBOFMO2hq5Dn8oQyaVEd/BaAf0IF+hDGJRD0WGHGJC9FM5SjDEBGWbV1pkdtWeD Xrem7VzUkiorMULm73irPxf7awyfayqr8TeYg084ByLlGrcm3GL/AA+yRqk5mEazxrDSss 7W32e3eAG9bqMiMBwBwm4U9/rWd0dHAALUTp/ZRnFcswpWBRj/7T5RacHeTw X-ME-Proxy: Feedback-ID: i559e4809:Fastmail Received: by mail.messagingengine.com (Postfix) with ESMTPA; Tue, 2 Jun 2026 05:40:50 -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 v6 04/11] net: Enable BIG TCP with partial GSO Date: Tue, 2 Jun 2026 11:39:24 +0200 Message-ID: <20260602093931.516281-5-alice.kernel@fastmail.im> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260602093931.516281-1-alice.kernel@fastmail.im> References: <20260602093931.516281-1-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 c64693fcb2d1..5dcee79df8cf 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -4773,6 +4773,7 @@ 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); @@ -4788,7 +4789,7 @@ 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) { @@ -4816,7 +4817,7 @@ 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; @@ -4850,9 +4851,8 @@ 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 @@ -4876,7 +4876,7 @@ 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