From mboxrd@z Thu Jan 1 00:00:00 1970 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 3886D263F4A for ; Tue, 1 Sep 2026 22:21:39 +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=1788301300; cv=none; b=R96ivoBx4JFghC824MYCzsJbFRh4aFKucEq6jxvm8ZZRowsMf9+iywPJPBUwCIki7QtcEzG16tSsyWT0v/1NW4m3HTr24crHZqZ2m/3otT6vhqiu2QuOUjZcxRHfav4co/n2E4XOpDJ7FKUB7LE/ObbqWHgyG1+MjLGHt09M+UU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788301300; c=relaxed/simple; bh=nEkkgg9rjvnXkRNu+uPQTbHQOUkRQWjrmO2Yg98Mn0M=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Kr5EFhfqdoxA99eD00F3XI0SO6mExnV8OcRVSp2VWbCAdWW17l08YLcqrsJf7YMBQMdsuuAgEFEJZeL2EUE5c6gWcHAbBX67mKLrhxENZ3HbktOyweu1Y/9VCWvSc+CqFtDOvNim7jHPXBwWpvXsxib/w20JsY40W7WtKgMgLK0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=KfUgfpZO; 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="KfUgfpZO" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 74D731F00A3A; Tue, 1 Sep 2026 22:21:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788301299; bh=2UUzsxpp4k7ufuFDYlc8zhrCf8z738WWyvYdYu5oho0=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=KfUgfpZOrYavC0aQmqATg9rw261P6G26bMzWLDXLH804D+/zH758xsoiOIE9j1SNl Ak0pW3xlo0LD+NAKRlM79nNsdQRKItA36ye8R+QktcTiwhbnYv4aEAuOOW+SjXjIhj KJ88qo8aVgsAh6xl5Gu+t/w1A/DLvcBoEAWVPPnI2FSCJDReGYmh+VXMbtXC4QIsZg IdLrqu5LOaVReRLSoJeEGGI0SPNwNU9QjkfKJOoRW/rz+ucB+MlR0xasRhJUWIIHoR KYUhxda8Jat3whcMfgcmtiaXk0VbTLJ3zHbQJG8AUBVZ4lHDWWlwGi9Su2A0zwtqAX lyR34W0miIH9A== From: Sasha Levin To: stable@vger.kernel.org Cc: Eric Dumazet , Kuniyuki Iwashima , Jakub Kicinski , Sasha Levin Subject: [PATCH 5.15.y 3/4] ipv4: use dst4_mtu() instead of dst_mtu() Date: Tue, 1 Sep 2026 18:21:33 -0400 Message-ID: <20260901222134.1700802-3-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260901222134.1700802-1-sashal@kernel.org> References: <2026083106-sterile-daunting-b716@gregkh> <20260901222134.1700802-1-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 fe8570186f100b6cc499b2f7705946baf1388cde ] When we expect an IPv4 dst, use dst4_mtu() instead of dst_mtu() to save some code space. Signed-off-by: Eric Dumazet Reviewed-by: Kuniyuki Iwashima Link: https://patch.msgid.link/20260130210303.3888261-8-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/ipv4/icmp.c | 2 +- net/ipv4/ip_output.c | 4 ++-- net/ipv4/ip_sockglue.c | 2 +- net/ipv4/ipmr.c | 2 +- net/ipv4/netfilter/nf_reject_ipv4.c | 2 +- net/ipv4/tcp_ipv4.c | 13 ++++++------- net/ipv6/sit.c | 2 +- 7 files changed, 13 insertions(+), 14 deletions(-) diff --git a/net/ipv4/icmp.c b/net/ipv4/icmp.c index 49c94aebac32d..b1812362f0965 100644 --- a/net/ipv4/icmp.c +++ b/net/ipv4/icmp.c @@ -768,7 +768,7 @@ void __icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info, /* RFC says return as much as we can without exceeding 576 bytes. */ - room = dst_mtu(&rt->dst); + room = dst4_mtu(&rt->dst); if (room > 576) room = 576; room -= sizeof(struct iphdr) + icmp_param.replyopts.opt.opt.optlen; diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c index fb64f5fcc422f..ffa8d6363a820 100644 --- a/net/ipv4/ip_output.c +++ b/net/ipv4/ip_output.c @@ -1262,7 +1262,7 @@ static int ip_setup_cork(struct sock *sk, struct inet_cork *cork, return -EFAULT; cork->fragsize = ip_sk_use_pmtu(sk) ? - dst_mtu(&rt->dst) : READ_ONCE(rt->dst.dev->mtu); + dst4_mtu(&rt->dst) : READ_ONCE(rt->dst.dev->mtu); if (!inetdev_valid_mtu(cork->fragsize)) return -ENETUNREACH; @@ -1528,7 +1528,7 @@ struct sk_buff *__ip_make_skb(struct sock *sk, * locally. */ if (inet->pmtudisc == IP_PMTUDISC_DO || inet->pmtudisc == IP_PMTUDISC_PROBE || - (skb->len <= dst_mtu(&rt->dst) && + (skb->len <= dst4_mtu(&rt->dst) && ip_dont_fragment(sk, &rt->dst))) df = htons(IP_DF); diff --git a/net/ipv4/ip_sockglue.c b/net/ipv4/ip_sockglue.c index 3620dc739a5bf..f985d9a0dcdac 100644 --- a/net/ipv4/ip_sockglue.c +++ b/net/ipv4/ip_sockglue.c @@ -1631,7 +1631,7 @@ static int do_ip_getsockopt(struct sock *sk, int level, int optname, val = 0; dst = sk_dst_get(sk); if (dst) { - val = dst_mtu(dst); + val = dst4_mtu(dst); dst_release(dst); } if (!val) { diff --git a/net/ipv4/ipmr.c b/net/ipv4/ipmr.c index 5e582eab1ea19..1a9d499d914bf 100644 --- a/net/ipv4/ipmr.c +++ b/net/ipv4/ipmr.c @@ -1860,7 +1860,7 @@ static void ipmr_queue_xmit(struct net *net, struct mr_table *mrt, dev = rt->dst.dev; - if (skb->len+encap > dst_mtu(&rt->dst) && (ntohs(iph->frag_off) & IP_DF)) { + if (skb->len+encap > dst4_mtu(&rt->dst) && (ntohs(iph->frag_off) & IP_DF)) { /* Do not fragment multicasts. Alas, IPv4 does not * allow to send ICMP, so that packets will disappear * to blackhole. diff --git a/net/ipv4/netfilter/nf_reject_ipv4.c b/net/ipv4/netfilter/nf_reject_ipv4.c index fbd264aa0a7ec..f64552b2cb832 100644 --- a/net/ipv4/netfilter/nf_reject_ipv4.c +++ b/net/ipv4/netfilter/nf_reject_ipv4.c @@ -298,7 +298,7 @@ void nf_send_reset(struct net *net, struct sock *sk, struct sk_buff *oldskb, niph = ip_hdr(nskb); /* "Never happens" */ - if (nskb->len > dst_mtu(skb_dst(nskb))) + if (nskb->len > dst4_mtu(skb_dst(nskb))) goto free_nskb; nf_ct_attach(nskb, oldskb); diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c index f7693166c5161..6f97dfbc5343d 100644 --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -352,7 +352,7 @@ void tcp_v4_mtu_reduced(struct sock *sk) { struct inet_sock *inet = inet_sk(sk); struct dst_entry *dst; - u32 mtu; + u32 mtu, dmtu; if ((1 << sk->sk_state) & (TCPF_LISTEN | TCPF_CLOSE)) return; @@ -364,15 +364,14 @@ void tcp_v4_mtu_reduced(struct sock *sk) /* Something is about to be wrong... Remember soft error * for the case, if this connection will not able to recover. */ - if (mtu < dst_mtu(dst) && ip_dont_fragment(sk, dst)) + dmtu = dst4_mtu(dst); + if (mtu < dmtu && ip_dont_fragment(sk, dst)) WRITE_ONCE(sk->sk_err_soft, EMSGSIZE); - mtu = dst_mtu(dst); - if (inet->pmtudisc != IP_PMTUDISC_DONT && ip_sk_accept_pmtu(sk) && - inet_csk(sk)->icsk_pmtu_cookie > mtu) { - tcp_sync_mss(sk, mtu); + inet_csk(sk)->icsk_pmtu_cookie > dmtu) { + tcp_sync_mss(sk, dmtu); /* Resend the TCP packet because it's * clear that the old packet has been @@ -1614,7 +1613,7 @@ struct sock *tcp_v4_syn_recv_sock(const struct sock *sk, struct sk_buff *skb, tcp_ca_openreq_child(newsk, dst); - tcp_sync_mss(newsk, dst_mtu(dst)); + tcp_sync_mss(newsk, dst4_mtu(dst)); newtp->advmss = tcp_mss_clamp(tcp_sk(sk), dst_metric_advmss(dst)); tcp_initialize_rcv_mss(newsk); diff --git a/net/ipv6/sit.c b/net/ipv6/sit.c index 4b16ddc3d6c7f..3f8e03cded539 100644 --- a/net/ipv6/sit.c +++ b/net/ipv6/sit.c @@ -974,7 +974,7 @@ static netdev_tx_t ipip6_tunnel_xmit(struct sk_buff *skb, iph6 = ipv6_hdr(skb); if (df) { - mtu = dst_mtu(&rt->dst) - t_hlen; + mtu = dst4_mtu(&rt->dst) - t_hlen; if (mtu < IPV4_MIN_MTU) { DEV_STATS_INC(dev, collisions); -- 2.53.0