[PATCH] [IPV6] clean-up advmss calculation

[YOSHIFUJI Hideaki / 吉藤英明 <yoshfuji@xxxxxxxxxxxxxx>]

Hello.

This patch introduces ipv6_advmss() and clean-up advmss calculation.
Thanks.

Index: linux-2.5/net/ipv6/route.c
===================================================================
RCS file: /home/cvs/linux-2.5/net/ipv6/route.c,v
retrieving revision 1.40
diff -u -r1.40 route.c
--- linux-2.5/net/ipv6/route.c  9 Jun 2003 17:26:52 -0000       1.40
+++ linux-2.5/net/ipv6/route.c  20 Jun 2003 13:28:03 -0000
@@ -600,6 +600,22 @@
        return mtu;
 }
 
+static inline unsigned int ipv6_advmss(unsigned int mtu)
+{
+       if (mtu < ip6_rt_min_advmss)
+               mtu = ip6_rt_min_advmss;
+
+       /*
+        * Maximal non-jumbo IPv6 payload is 65535 and 
+        * corresponding MSS is 65535 - tcp_header_size. 
+        * 65535 is also valid and means: "any MSS, 
+        * rely only on pmtu discovery"
+        */
+       if (mtu > 65535 - sizeof(struct tcphdr))
+               mtu = 65535;
+       return mtu;
+}
+
 static int ipv6_get_hoplimit(struct net_device *dev)
 {
        int hoplimit = ipv6_devconf.hop_limit;
@@ -790,16 +806,7 @@
        if (!rt->u.dst.metrics[RTAX_MTU-1])
                rt->u.dst.metrics[RTAX_MTU-1] = ipv6_get_mtu(dev);
        if (!rt->u.dst.metrics[RTAX_ADVMSS-1])
-               rt->u.dst.metrics[RTAX_ADVMSS-1] =
-                       max_t(unsigned int, dst_pmtu(&rt->u.dst) - 60,
-                             ip6_rt_min_advmss);
-
-       /* Maximal non-jumbo IPv6 payload is 65535 and corresponding
-          MSS is 65535 - tcp_header_size. 65535 is also valid and
-          means: "any MSS, rely only on pmtu discovery"
-        */
-       if (dst_metric(&rt->u.dst, RTAX_ADVMSS) > 65535-20)
-               rt->u.dst.metrics[RTAX_ADVMSS-1] = 65535;
+               rt->u.dst.metrics[RTAX_ADVMSS-1] = 
ipv6_advmss(dst_pmtu(&rt->u.dst));
        rt->u.dst.dev = dev;
        return rt6_ins(rt, nlh, _rtattr);
 
@@ -952,9 +959,7 @@
        nrt->rt6i_nexthop = neigh_clone(neigh);
        /* Reset pmtu, it may be better */
        nrt->u.dst.metrics[RTAX_MTU-1] = ipv6_get_mtu(neigh->dev);
-       nrt->u.dst.metrics[RTAX_ADVMSS-1] = max_t(unsigned int, 
dst_pmtu(&nrt->u.dst) - 60, ip6_rt_min_advmss);
-       if (nrt->u.dst.metrics[RTAX_ADVMSS-1] > 65535-20)
-               nrt->u.dst.metrics[RTAX_ADVMSS-1] = 65535;
+       nrt->u.dst.metrics[RTAX_ADVMSS-1] = ipv6_advmss(dst_pmtu(&nrt->u.dst));
 
        if (rt6_ins(nrt, NULL, NULL))
                goto out;
@@ -1214,9 +1219,7 @@
        rt->u.dst.output = ip6_output;
        rt->rt6i_dev = &loopback_dev;
        rt->u.dst.metrics[RTAX_MTU-1] = ipv6_get_mtu(rt->rt6i_dev);
-       rt->u.dst.metrics[RTAX_ADVMSS-1] = max_t(unsigned int, 
dst_pmtu(&rt->u.dst) - 60, ip6_rt_min_advmss);
-       if (rt->u.dst.metrics[RTAX_ADVMSS-1] > 65535-20)
-               rt->u.dst.metrics[RTAX_ADVMSS-1] = 65535;
+       rt->u.dst.metrics[RTAX_ADVMSS-1] = ipv6_advmss(dst_pmtu(&rt->u.dst));
        rt->u.dst.metrics[RTAX_HOPLIMIT-1] = ipv6_get_hoplimit(rt->rt6i_dev);
        rt->u.dst.obsolete = -1;
 
@@ -1312,9 +1315,7 @@
              (dst_pmtu(&rt->u.dst) < arg->mtu &&
              dst_pmtu(&rt->u.dst) == idev->cnf.mtu6)))
                rt->u.dst.metrics[RTAX_MTU-1] = arg->mtu;
-       rt->u.dst.metrics[RTAX_ADVMSS-1] = max_t(unsigned int, arg->mtu - 60, 
ip6_rt_min_advmss);
-       if (rt->u.dst.metrics[RTAX_ADVMSS-1] > 65535-20)
-               rt->u.dst.metrics[RTAX_ADVMSS-1] = 65535;
+       rt->u.dst.metrics[RTAX_ADVMSS-1] = ipv6_advmss(arg->mtu);
        return 0;
 }
 



-- 
Hideaki YOSHIFUJI @ USAGI Project <yoshfuji@xxxxxxxxxxxxxx>
GPG FP: 9022 65EB 1ECF 3AD1 0BDF  80D8 4807 F894 E062 0EEA