Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 50840313E00 for ; Tue, 1 Sep 2026 00:21:02 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788222063; cv=none; b=CNV6GYcz5SjCyhEsSnbm1lsrhJv7ypx1kV2PN4keeXjugfRDAlh86/y9FVB6EzuH99hLvDGaefYMHqqA07YG0mNY0JQPglyDPIisvDwyT1SM2qeGy1ODoCHCpe9yUdNWHQ3azlY0qa5IYuZgzhs5fgAqMCv3oF4UW63J3mCY4nY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788222063; c=relaxed/simple; bh=Y1y+6U1aLbSbijwUDhp9FXayZDPfOe28mV+ci21fct0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=m8dV49eWMOujdVFRNSFa478fnKtRR/UvNm2yscgNuGTpSwpc/UrzhcYlH/1EvH8EcGspTR34i+ta7glh105/FxqT46J/bobg72kbbWZYx5bouSmYUS4CnZaCsRRZm/DHpcXrwmvMDRlR/vZ9zj+w5KfHr1Hx52HFOFxatsoDsHI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Angm/TJK; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Angm/TJK" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 956931F00A3F; Tue, 1 Sep 2026 00:21:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788222062; bh=ZvotDDc/ccpXbEiI9ts/Ebq1T5/swXrw1JvvuFEiEfA=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=Angm/TJKbJFBluy3Q5dhMwq8aARAcnXjFVNexOXOgUsi5SGJNwn71quNwozRplYAH +zqlT/JihPrNxWpA4dG9U9lQXtFogA5Pt3KeOPZv65K2wZbMoAeS3F9FbZxfVI+bcn s4UlcRGtrSyjRuaQayDcUCes4egWy9qpuhKcvupvztWUmpGU++Jr3EsZ04y5/xPUsD +zW9ziTIccdz3BcBgi4CXrtqlWRQncxMQ9uPGtKDoO97w3P20vKjgq/5gXMyJ7bO8x EhZgcHfKuwqqvzCH7gcCajHzcIjigGH6nMkRhIIV+L6sIGJPdW46L2rddLMsucLc3C 4aW4xI41mcAFw== From: Sasha Levin To: stable@vger.kernel.org Cc: Eric Dumazet , Kuniyuki Iwashima , Jakub Kicinski , Sasha Levin Subject: [PATCH 6.18.y 4/6] ipv6: use dst6_mtu() instead of dst_mtu() Date: Mon, 31 Aug 2026 20:20:55 -0400 Message-ID: <20260901002057.2024614-4-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260901002057.2024614-1-sashal@kernel.org> References: <2026083104-huddle-balancing-d57b@gregkh> <20260901002057.2024614-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Eric Dumazet [ Upstream commit b40f0130a23b6bab8b359e158a40af81f11f14be ] When we expect an IPv6 dst, use dst6_mtu() instead of dst_mtu() to save some code space. Due to current dst6_mtu() implementation, only convert users in IPv6 stack. Signed-off-by: Eric Dumazet Reviewed-by: Kuniyuki Iwashima Link: https://patch.msgid.link/20260130210303.3888261-7-edumazet@google.com Signed-off-by: Jakub Kicinski Stable-dep-of: 870a9e42ecc6 ("tcp: clamp route advmss to TCP_MIN_MSS") Signed-off-by: Sasha Levin --- net/ipv6/ip6_gre.c | 2 +- net/ipv6/ip6_output.c | 6 +++--- net/ipv6/ip6_tunnel.c | 4 ++-- net/ipv6/ipv6_sockglue.c | 4 ++-- net/ipv6/route.c | 10 ++++++---- net/ipv6/tcp_ipv6.c | 9 +++++---- 6 files changed, 19 insertions(+), 16 deletions(-) diff --git a/net/ipv6/ip6_gre.c b/net/ipv6/ip6_gre.c index 58b473c157c82..4fbda6d83c0dc 100644 --- a/net/ipv6/ip6_gre.c +++ b/net/ipv6/ip6_gre.c @@ -1057,7 +1057,7 @@ static netdev_tx_t ip6erspan_tunnel_xmit(struct sk_buff *skb, /* TooBig packet may have updated dst->dev's mtu */ if (!t->parms.collect_md && dst) { mtu = READ_ONCE(dst_dev(dst)->mtu); - if (dst_mtu(dst) > mtu) + if (dst6_mtu(dst) > mtu) dst->ops->update_pmtu(dst, NULL, skb, mtu, false); } err = ip6_tnl_xmit(skb, dev, dsfield, &fl6, encap_limit, &mtu, diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c index d048321733b38..7545fdbf07da2 100644 --- a/net/ipv6/ip6_output.c +++ b/net/ipv6/ip6_output.c @@ -355,7 +355,7 @@ int ip6_xmit(const struct sock *sk, struct sk_buff *skb, struct flowi6 *fl6, skb->priority = priority; skb->mark = mark; - mtu = dst_mtu(dst); + mtu = dst6_mtu(dst); if (likely((skb->len <= mtu) || skb->ignore_df || skb_is_gso(skb))) { IP6_INC_STATS(net, idev, IPSTATS_MIB_OUTREQUESTS); @@ -1405,10 +1405,10 @@ static int ip6_setup_cork(struct sock *sk, struct inet_cork_full *cork, v6_cork->dontfrag = ipc6->dontfrag; if (rt->dst.flags & DST_XFRM_TUNNEL) mtu = READ_ONCE(np->pmtudisc) >= IPV6_PMTUDISC_PROBE ? - READ_ONCE(rt->dst.dev->mtu) : dst_mtu(&rt->dst); + READ_ONCE(rt->dst.dev->mtu) : dst6_mtu(&rt->dst); else mtu = READ_ONCE(np->pmtudisc) >= IPV6_PMTUDISC_PROBE ? - READ_ONCE(rt->dst.dev->mtu) : dst_mtu(xfrm_dst_path(&rt->dst)); + READ_ONCE(rt->dst.dev->mtu) : dst6_mtu(xfrm_dst_path(&rt->dst)); frag_size = READ_ONCE(np->frag_size); if (frag_size && frag_size < mtu) diff --git a/net/ipv6/ip6_tunnel.c b/net/ipv6/ip6_tunnel.c index ba3084cecc979..e321feca8926d 100644 --- a/net/ipv6/ip6_tunnel.c +++ b/net/ipv6/ip6_tunnel.c @@ -643,7 +643,7 @@ ip4ip6_err(struct sk_buff *skb, struct inet6_skb_parm *opt, /* change mtu on this route */ if (rel_type == ICMP_DEST_UNREACH && rel_code == ICMP_FRAG_NEEDED) { - if (rel_info > dst_mtu(skb_dst(skb2))) + if (rel_info > dst6_mtu(skb_dst(skb2))) goto out; skb_dst_update_pmtu_no_confirm(skb2, rel_info); @@ -1195,7 +1195,7 @@ int ip6_tnl_xmit(struct sk_buff *skb, struct net_device *dev, __u8 dsfield, t->parms.name); goto tx_err_dst_release; } - mtu = dst_mtu(dst) - eth_hlen - psh_hlen - t->tun_hlen; + mtu = dst6_mtu(dst) - eth_hlen - psh_hlen - t->tun_hlen; if (encap_limit >= 0) { max_headroom += 8; mtu -= 8; diff --git a/net/ipv6/ipv6_sockglue.c b/net/ipv6/ipv6_sockglue.c index a61e742794f9e..d784a8644ff20 100644 --- a/net/ipv6/ipv6_sockglue.c +++ b/net/ipv6/ipv6_sockglue.c @@ -1184,7 +1184,7 @@ int do_ipv6_getsockopt(struct sock *sk, int level, int optname, rcu_read_lock(); dst = __sk_dst_get(sk); if (dst) - val = dst_mtu(dst); + val = dst6_mtu(dst); rcu_read_unlock(); if (!val) return -ENOTCONN; @@ -1283,7 +1283,7 @@ int do_ipv6_getsockopt(struct sock *sk, int level, int optname, rcu_read_lock(); dst = __sk_dst_get(sk); if (dst) - mtuinfo.ip6m_mtu = dst_mtu(dst); + mtuinfo.ip6m_mtu = dst6_mtu(dst); rcu_read_unlock(); if (!mtuinfo.ip6m_mtu) return -ENOTCONN; diff --git a/net/ipv6/route.c b/net/ipv6/route.c index 5894f7dd4d4d7..5ad2d92319562 100644 --- a/net/ipv6/route.c +++ b/net/ipv6/route.c @@ -2053,6 +2053,8 @@ static void rt6_update_exception_stamp_rt(struct rt6_info *rt) static bool rt6_mtu_change_route_allowed(struct inet6_dev *idev, struct rt6_info *rt, int mtu) { + u32 dmtu = dst6_mtu(&rt->dst); + /* If the new MTU is lower than the route PMTU, this new MTU will be the * lowest MTU in the path: always allow updating the route PMTU to * reflect PMTU decreases. @@ -2063,10 +2065,10 @@ static bool rt6_mtu_change_route_allowed(struct inet6_dev *idev, * handle this. */ - if (dst_mtu(&rt->dst) >= mtu) + if (dmtu >= mtu) return true; - if (dst_mtu(&rt->dst) == idev->cnf.mtu6) + if (dmtu == idev->cnf.mtu6) return true; return false; @@ -2936,7 +2938,7 @@ static void __ip6_rt_update_pmtu(struct dst_entry *dst, const struct sock *sk, if (mtu < IPV6_MIN_MTU) return; - if (mtu >= dst_mtu(dst)) + if (mtu >= dst6_mtu(dst)) return; if (!rt6_cache_allowed_for_pmtu(rt6)) { @@ -3252,7 +3254,7 @@ EXPORT_SYMBOL_GPL(ip6_sk_redirect); static unsigned int ip6_default_advmss(const struct dst_entry *dst) { - unsigned int mtu = dst_mtu(dst); + unsigned int mtu = dst6_mtu(dst); struct net *net; mtu -= sizeof(struct ipv6hdr) + sizeof(struct tcphdr); diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c index 952bf49efbc6a..cedfdf728cd41 100644 --- a/net/ipv6/tcp_ipv6.c +++ b/net/ipv6/tcp_ipv6.c @@ -351,7 +351,7 @@ static int tcp_v6_connect(struct sock *sk, struct sockaddr *uaddr, static void tcp_v6_mtu_reduced(struct sock *sk) { struct dst_entry *dst; - u32 mtu; + u32 mtu, dmtu; if ((1 << sk->sk_state) & (TCPF_LISTEN | TCPF_CLOSE)) return; @@ -368,8 +368,9 @@ static void tcp_v6_mtu_reduced(struct sock *sk) if (!dst) return; - if (inet_csk(sk)->icsk_pmtu_cookie > dst_mtu(dst)) { - tcp_sync_mss(sk, dst_mtu(dst)); + dmtu = dst6_mtu(dst); + if (inet_csk(sk)->icsk_pmtu_cookie > dmtu) { + tcp_sync_mss(sk, dmtu); tcp_simple_retransmit(sk); } } @@ -1499,7 +1500,7 @@ static struct sock *tcp_v6_syn_recv_sock(const struct sock *sk, struct sk_buff * tcp_ca_openreq_child(newsk, dst); - tcp_sync_mss(newsk, dst_mtu(dst)); + tcp_sync_mss(newsk, dst6_mtu(dst)); newtp->advmss = tcp_mss_clamp(tcp_sk(sk), dst_metric_advmss(dst)); tcp_initialize_rcv_mss(newsk); -- 2.53.0