Commit 46517008 authored by David S. Miller's avatar David S. Miller
Browse files

ipv4: Kill ip_rt_frag_needed(). 



There is zero point to this function.

It's only real substance is to perform an extremely outdated BSD4.2
ICMP check, which we can safely remove.  If you really have a MTU
limited link being routed by a BSD4.2 derived system, here's a nickel
go buy yourself a real router.

The other actions of ip_rt_frag_needed(), checking and conditionally
updating the peer, are done by the per-protocol handlers of the ICMP
event.

TCP, UDP, et al. have a handler which will receive this event and
transmit it back into the associated route via dst_ops->update_pmtu().

This simplification is important, because it eliminates the one place
where we do not have a proper route context in which to make an
inetpeer lookup.

Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 97bab73f

include/net/route.h

+0 −2
Original line number Diff line number Diff line
@@ -215,8 +215,6 @@ static inline int ip_route_input_noref(struct sk_buff *skb, __be32 dst, __be32 s 
	return ip_route_input_common(skb, dst, src, tos, devin, true);

}



extern unsigned short	ip_rt_frag_needed(struct net *net, const struct iphdr *iph,

					  unsigned short new_mtu, struct net_device *dev);

extern void		ip_rt_send_redirect(struct sk_buff *skb);



extern unsigned int		inet_addr_type(struct net *net, __be32 addr);

net/ipv4/icmp.c

+1 −3
Original line number Diff line number Diff line
@@ -673,9 +673,7 @@ static void icmp_unreach(struct sk_buff *skb) 
				LIMIT_NETDEBUG(KERN_INFO pr_fmt("%pI4: fragmentation needed and DF set\n"),

					       &iph->daddr);

			} else {

				info = ip_rt_frag_needed(net, iph,

							 ntohs(icmph->un.frag.mtu),

							 skb->dev);

				info = ntohs(icmph->un.frag.mtu);

				if (!info)

					goto out;

			}

net/ipv4/route.c

+0 −61
Original line number Diff line number Diff line
@@ -1664,67 +1664,6 @@ out: kfree_skb(skb); 
	return 0;

}



/*

 *	The last two values are not from the RFC but

 *	are needed for AMPRnet AX.25 paths.

 */



static const unsigned short mtu_plateau[] =

{32000, 17914, 8166, 4352, 2002, 1492, 576, 296, 216, 128 };



static inline unsigned short guess_mtu(unsigned short old_mtu)

{

	int i;



	for (i = 0; i < ARRAY_SIZE(mtu_plateau); i++)

		if (old_mtu > mtu_plateau[i])

			return mtu_plateau[i];

	return 68;

}



unsigned short ip_rt_frag_needed(struct net *net, const struct iphdr *iph,

				 unsigned short new_mtu,

				 struct net_device *dev)

{

	unsigned short old_mtu = ntohs(iph->tot_len);

	unsigned short est_mtu = 0;

	struct inet_peer *peer;



	peer = inet_getpeer_v4(net->ipv4.peers, iph->daddr, 1);

	if (peer) {

		unsigned short mtu = new_mtu;



		if (new_mtu < 68 || new_mtu >= old_mtu) {

			/* BSD 4.2 derived systems incorrectly adjust

			 * tot_len by the IP header length, and report

			 * a zero MTU in the ICMP message.

			 */

			if (mtu == 0 &&

			    old_mtu >= 68 + (iph->ihl << 2))

				old_mtu -= iph->ihl << 2;

			mtu = guess_mtu(old_mtu);

		}



		if (mtu < ip_rt_min_pmtu)

			mtu = ip_rt_min_pmtu;

		if (!peer->pmtu_expires || mtu < peer->pmtu_learned) {

			unsigned long pmtu_expires;



			pmtu_expires = jiffies + ip_rt_mtu_expires;

			if (!pmtu_expires)

				pmtu_expires = 1UL;



			est_mtu = mtu;

			peer->pmtu_learned = mtu;

			peer->pmtu_expires = pmtu_expires;

			atomic_inc(&__rt_peer_genid);

		}



		inet_putpeer(peer);

	}

	return est_mtu ? : new_mtu;

}



static void check_peer_pmtu(struct dst_entry *dst, struct inet_peer *peer)

{

	unsigned long expires = ACCESS_ONCE(peer->pmtu_expires);

net/rxrpc/ar-error.c

+0 −4
Original line number Diff line number Diff line
@@ -81,10 +81,6 @@ void rxrpc_UDP_error_report(struct sock *sk) 
			_net("I/F MTU %u", mtu);

		}



		/* ip_rt_frag_needed() may have eaten the info */

		if (mtu == 0)

			mtu = ntohs(icmp_hdr(skb)->un.frag.mtu);



		if (mtu == 0) {

			/* they didn't give us a size, estimate one */

			if (mtu > 1500) {

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