On Wed, 2017-04-12 at 10:32 +0800, gfree.w...@foxmail.com wrote:
> diff --git a/net/ipv4/route.c b/net/ipv4/route.c
more trivia:
> @@ -1250,14 +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;
> - }
> + advmss = min(advmss, IPV4_MAX_PMTU - header_size);
> return advmss;
> }
This would probably be simpler to read as:
return min(advmss, IPV4_MAX_PMTU - header_size);
though it's almost certain that the compiler emits identical
object code.
