From a871e2f5c4a0187818dc7e1984b2cd86a2c61a4c Mon Sep 17 00:00:00 2001
From: Kazuki Yamaguchi <k@rhe.jp>
Date: Wed, 24 Feb 2021 22:36:57 +0900
Subject: net: add comments to code where MTU is handed incorrectly

But I'm not going to fix them - it's unlikely I actually hit these code
paths.
---
 net/ipv4/ip_output.c | 1 +
 net/ipv4/raw.c       | 1 +
 net/ipv6/raw.c       | 1 +
 net/ipv6/route.c     | 2 ++
 4 files changed, 5 insertions(+)

diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
index 2ed0b01f72f0..7870b27e62aa 100644
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -1264,6 +1264,7 @@ static int ip_setup_cork(struct sock *sk, struct inet_cork *cork,
 		cork->addr = ipc->addr;
 	}
 
+	/* XXX: MTU */
 	cork->fragsize = ip_sk_use_pmtu(sk) ?
 			 dst_mtu(&rt->dst) : READ_ONCE(rt->dst.dev->mtu);
 
diff --git a/net/ipv4/raw.c b/net/ipv4/raw.c
index 50a73178d63a..331197f08497 100644
--- a/net/ipv4/raw.c
+++ b/net/ipv4/raw.c
@@ -355,6 +355,7 @@ static int raw_send_hdrinc(struct sock *sk, struct flowi4 *fl4,
 	struct rtable *rt = *rtp;
 	int hlen, tlen;
 
+	/* XXX: MTU */
 	if (length > rt->dst.dev->mtu) {
 		ip_local_error(sk, EMSGSIZE, fl4->daddr, inet->inet_dport,
 			       rt->dst.dev->mtu);
diff --git a/net/ipv6/raw.c b/net/ipv6/raw.c
index 1f56d9aae589..4987eb7e1368 100644
--- a/net/ipv6/raw.c
+++ b/net/ipv6/raw.c
@@ -628,6 +628,7 @@ static int rawv6_send_hdrinc(struct sock *sk, struct msghdr *msg, int length,
 	int hlen = LL_RESERVED_SPACE(rt->dst.dev);
 	int tlen = rt->dst.dev->needed_tailroom;
 
+	/* XXX: MTU */
 	if (length > rt->dst.dev->mtu) {
 		ipv6_local_error(sk, EMSGSIZE, fl6, rt->dst.dev->mtu);
 		return -EMSGSIZE;
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 506f258bfa76..42b33b6cea0a 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -2004,6 +2004,7 @@ static bool rt6_mtu_change_route_allowed(struct inet6_dev *idev,
 	if (dst_mtu(&rt->dst) >= mtu)
 		return true;
 
+	/* XXX: MTU */
 	if (dst_mtu(&rt->dst) == idev->cnf.mtu6)
 		return true;
 
@@ -4798,6 +4799,7 @@ static int fib6_nh_mtu_change(struct fib6_nh *nh, void *_arg)
 		struct inet6_dev *idev = __in6_dev_get(arg->dev);
 		u32 mtu = f6i->fib6_pmtu;
 
+		/* XXX: MTU */
 		if (mtu >= arg->mtu ||
 		    (mtu < arg->mtu && mtu == idev->cnf.mtu6))
 			fib6_metric_set(f6i, RTAX_MTU, arg->mtu);
-- 
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