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net: ipv4: Consolidate ipv4_mtu and ip_dst_mtu_maybe_forward

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Consolidate IPv4 MTU code the same way it is done in IPv6 to have code
aligned in both address families

Signed-off-by: Vadim Fedorenko <vfedorenko@novek.ru>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Vadim Fedorenko 2021-07-20 23:06:28 +03:00 committed by David S. Miller
parent 427faee167
commit ac6627a28d
2 changed files with 19 additions and 24 deletions
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22
include/net/ip.h
View File

@ -436,18 +436,32 @@ static inline bool ip_sk_ignore_df(const struct sock *sk)
static inline unsigned int ip_dst_mtu_maybe_forward(const struct dst_entry *dst,
bool forwarding)
{
const struct rtable *rt = container_of(dst, struct rtable, dst);
struct net *net = dev_net(dst->dev);
unsigned int mtu;
if (net->ipv4.sysctl_ip_fwd_use_pmtu ||
ip_mtu_locked(dst) ||
!forwarding)
return dst_mtu(dst);
!forwarding) {
mtu = rt->rt_pmtu;
if (mtu && time_before(jiffies, rt->dst.expires))
goto out;
}
/* 'forwarding = true' case should always honour route mtu */
mtu = dst_metric_raw(dst, RTAX_MTU);
if (!mtu)
mtu = min(READ_ONCE(dst->dev->mtu), IP_MAX_MTU);
if (mtu)
goto out;
mtu = READ_ONCE(dst->dev->mtu);
if (unlikely(ip_mtu_locked(dst))) {
if (rt->rt_uses_gateway && mtu > 576)
mtu = 576;
}
out:
mtu = min_t(unsigned int, mtu, IP_MAX_MTU);
return mtu - lwtunnel_headroom(dst->lwtstate, mtu);
}

21
net/ipv4/route.c
View File

@ -1299,26 +1299,7 @@ static unsigned int ipv4_default_advmss(const struct dst_entry *dst)
INDIRECT_CALLABLE_SCOPE unsigned int ipv4_mtu(const struct dst_entry *dst)
{
const struct rtable *rt = (const struct rtable *)dst;
unsigned int mtu = rt->rt_pmtu;
if (!mtu || time_after_eq(jiffies, rt->dst.expires))
mtu = dst_metric_raw(dst, RTAX_MTU);
if (mtu)
goto out;
mtu = READ_ONCE(dst->dev->mtu);
if (unlikely(ip_mtu_locked(dst))) {
if (rt->rt_uses_gateway && mtu > 576)
mtu = 576;
}
out:
mtu = min_t(unsigned int, mtu, IP_MAX_MTU);
return mtu - lwtunnel_headroom(dst->lwtstate, mtu);
return ip_dst_mtu_maybe_forward(dst, false);
}
EXPORT_INDIRECT_CALLABLE(ipv4_mtu);