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authorGao Feng <fgao@ikuai8.com>2017-04-12 12:34:03 +0800
committerDavid S. Miller <davem@davemloft.net>2017-04-13 13:19:48 -0400
commit7ed14d973f7c6742f4827fbbf6730cbe20888b8b (patch)
tree64d4241faceea5a52dc9d571753373908130e2cc /net/ipv4/route.c
parent29b904a0dd925bf2e3bcb45e478f21138b5efe3f (diff)
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: Gao Feng <fgao@ikuai8.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4/route.c')
-rw-r--r--net/ipv4/route.c12
1 files changed, 4 insertions, 8 deletions
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index 5e1e60546fce..0fcc2d5192bd 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -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);
+ 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 == 0) {
- advmss = max_t(unsigned int, dst->dev->mtu - 40,
- 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)

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