Commit ac6627a2 authored by Vadim Fedorenko's avatar Vadim Fedorenko Committed by David S. Miller
Browse files

net: ipv4: Consolidate ipv4_mtu and ip_dst_mtu_maybe_forward 



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

Signed-off-by: default avatarVadim Fedorenko <vfedorenko@novek.ru>
Reviewed-by: default avatarDavid Ahern <dsahern@kernel.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 427faee1

include/net/ip.h

+18 −4
Original line number Diff line number Diff line
@@ -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);

}

net/ipv4/route.c

+1 −20
Original line number Diff line number Diff line
@@ -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);