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ipv4: Kill ip_rt_frag_needed().

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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It's only real substance is to perform an extremely outdated BSD4.2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: David S. Miller <davem@davemloft.net>
This commit is contained in:
David S. Miller 2012-06-10 00:04:12 -07:00
parent 97bab73f98
commit 46517008e1
4 changed files with 1 additions and 70 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
include/net/route.h
View File

@ -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);

4
net/ipv4/icmp.c
View File

@ -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;
}

61
net/ipv4/route.c
View File

@ -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);

4
net/rxrpc/ar-error.c
View File

@ -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) {