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Commit 7ed14d97 authored by Gao Feng's avatar Gao Feng Committed by David S. Miller
Browse files

net: ipv4: Refine the ipv4_default_advmss 



1. Don't get the metric RTAX_ADVMSS of dst.
There are two reasons.
1) Its caller dst_metric_advmss has already invoke dst_metric_advmss
before invoke default_advmss.
2) The ipv4_default_advmss is used to get the default mss, it should
not try to get the metric like ip6_default_advmss.

2. Use sizeof(tcphdr)+sizeof(iphdr) instead of literal 40.

3. Define one new macro IPV4_MAX_PMTU instead of 65535 according to
RFC 2675, section 5.1.

Signed-off-by: default avatarGao Feng <fgao@ikuai8.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 29b904a0

include/net/ip.h

+2 −0
Original line number Diff line number Diff line
@@ -33,6 +33,8 @@ 
#include <net/flow.h>

#include <net/flow_dissector.h>



#define IPV4_MAX_PMTU		65535U		/* RFC 2675, Section 5.1 */



struct sock;



struct inet_skb_parm {

net/ipv4/route.c

+4 −8
Original line number Diff line number Diff line
@@ -1250,15 +1250,11 @@ static void set_class_tag(struct rtable *rt, u32 tag) 


static unsigned int ipv4_default_advmss(const struct dst_entry *dst)

{

	unsigned int advmss = dst_metric_raw(dst, RTAX_ADVMSS);



	if (advmss == 0) {

		advmss = max_t(unsigned int, dst->dev->mtu - 40,

	unsigned int header_size = sizeof(struct tcphdr) + sizeof(struct iphdr);

	unsigned int advmss = max_t(unsigned int, dst->dev->mtu - header_size,

				    ip_rt_min_advmss);

		if (advmss > 65535 - 40)

			advmss = 65535 - 40;

	}

	return advmss;



	return min(advmss, IPV4_MAX_PMTU - header_size);

}



static unsigned int ipv4_mtu(const struct dst_entry *dst)