ipv6: Stop rt6_info from using inet_peer's metrics

inet_peer is indexed by the dst address alone.  However, the fib6 tree
could have multiple routing entries (rt6_info) for the same dst. For
example,
1. A /128 dst via multiple gateways.
2. A RTF_CACHE route cloned from a /128 route.

In the above cases, all of them will share the same metrics and
step on each other.

This patch will steer away from inet_peer's metrics and use
dst_cow_metrics_generic() for everything.

Change Highlights:
1. Remove rt6_cow_metrics() which currently acquires metrics from
   inet_peer for DST_HOST route (i.e. /128 route).
2. Add rt6i_pmtu to take care of the pmtu update to avoid creating a
   full size metrics just to override the RTAX_MTU.
3. After (2), the RTF_CACHE route can also share the metrics with its
   dst.from route, by:
   dst_init_metrics(&cache_rt->dst, dst_metrics_ptr(cache_rt->dst.from), true);
4. Stop creating RTF_CACHE route by cloning another RTF_CACHE route.  Instead,
   directly clone from rt->dst.

   [ Currently, cloning from another RTF_CACHE is only possible during
     rt6_do_redirect().  Also, the old clone is removed from the tree
     immediately after the new clone is added. ]

   In case of cloning from an older redirect RTF_CACHE, it should work as
   before.

   In case of cloning from an older pmtu RTF_CACHE, this patch will forget
   the pmtu and re-learn it (if there is any) from the redirected route.

The _rt6i_peer and DST_METRICS_FORCE_OVERWRITE will be removed
in the next cleanup patch.

Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Reviewed-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Cc: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/net/ip6_fib.h b/include/net/ip6_fib.h
index 20e80fa7bbdd5a0effd39ed6761ac167912f7da3..7383a8cc8f845387aa0aadf8790bcef11b7e22d3 100644 (file)
--- a/include/net/ip6_fib.h
+++ b/include/net/ip6_fib.h
@@ -124,6 +124,7 @@ struct rt6_info {
        unsigned long                   _rt6i_peer;
 
        u32                             rt6i_metric;
+       u32                             rt6i_pmtu;
        /* more non-fragment space at head required */
        unsigned short                  rt6i_nfheader_len;
        u8                              rt6i_protocol;
@@ -189,15 +190,6 @@ static inline void rt6_update_expires(struct rt6_info *rt0, int timeout)
        rt0->rt6i_flags |= RTF_EXPIRES;
 }
 
-static inline void rt6_set_from(struct rt6_info *rt, struct rt6_info *from)
-{
-       struct dst_entry *new = (struct dst_entry *) from;
-
-       rt->rt6i_flags &= ~RTF_EXPIRES;
-       dst_hold(new);
-       rt->dst.from = new;
-}
-
 static inline void ip6_rt_put(struct rt6_info *rt)
 {
        /* dst_release() accepts a NULL parameter.

diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index aa4cfdd13f28de35a7b58ef5873ee4e80e22ee4d..4d6eb5d90cb4bde2c8c9ce570c69281e3187ca43 100644 (file)
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -92,6 +92,7 @@ static void           ip6_rt_update_pmtu(struct dst_entry *dst, struct sock *sk,
                                           struct sk_buff *skb, u32 mtu);
 static void            rt6_do_redirect(struct dst_entry *dst, struct sock *sk,
                                        struct sk_buff *skb);
+static void            rt6_dst_from_metrics_check(struct rt6_info *rt);
 static int rt6_score_route(struct rt6_info *rt, int oif, int strict);
 
 #ifdef CONFIG_IPV6_ROUTE_INFO
@@ -136,33 +137,12 @@ static struct inet_peer *rt6_get_peer_create(struct rt6_info *rt)
 
 static u32 *ipv6_cow_metrics(struct dst_entry *dst, unsigned long old)
 {
-       struct rt6_info *rt = (struct rt6_info *) dst;
-       struct inet_peer *peer;
-       u32 *p = NULL;
+       struct rt6_info *rt = (struct rt6_info *)dst;
 
-       if (!(rt->dst.flags & DST_HOST))
+       if (rt->rt6i_flags & RTF_CACHE)
+               return NULL;
+       else
                return dst_cow_metrics_generic(dst, old);
-
-       peer = rt6_get_peer_create(rt);
-       if (peer) {
-               u32 *old_p = __DST_METRICS_PTR(old);
-               unsigned long prev, new;
-
-               p = peer->metrics;
-               if (inet_metrics_new(peer) ||
-                   (old & DST_METRICS_FORCE_OVERWRITE))
-                       memcpy(p, old_p, sizeof(u32) * RTAX_MAX);
-
-               new = (unsigned long) p;
-               prev = cmpxchg(&dst->_metrics, old, new);
-
-               if (prev != old) {
-                       p = __DST_METRICS_PTR(prev);
-                       if (prev & DST_METRICS_READ_ONLY)
-                               p = NULL;
-               }
-       }
-       return p;
 }
 
 static inline const void *choose_neigh_daddr(struct rt6_info *rt,
@@ -323,8 +303,7 @@ static void ip6_dst_destroy(struct dst_entry *dst)
        struct inet6_dev *idev = rt->rt6i_idev;
        struct dst_entry *from = dst->from;
 
-       if (!(rt->dst.flags & DST_HOST))
-               dst_destroy_metrics_generic(dst);
+       dst_destroy_metrics_generic(dst);
 
        if (idev) {
                rt->rt6i_idev = NULL;
@@ -333,11 +312,6 @@ static void ip6_dst_destroy(struct dst_entry *dst)
 
        dst->from = NULL;
        dst_release(from);
-
-       if (rt6_has_peer(rt)) {
-               struct inet_peer *peer = rt6_peer_ptr(rt);
-               inet_putpeer(peer);
-       }
 }
 
 static void ip6_dst_ifdown(struct dst_entry *dst, struct net_device *dev,
@@ -1003,6 +977,7 @@ redo_rt6_select:
        goto redo_fib6_lookup_lock;
 
 out2:
+       rt6_dst_from_metrics_check(rt);
        rt->dst.lastuse = jiffies;
        rt->dst.__use++;
 
@@ -1111,6 +1086,13 @@ struct dst_entry *ip6_blackhole_route(struct net *net, struct dst_entry *dst_ori
  *     Destination cache support functions
  */
 
+static void rt6_dst_from_metrics_check(struct rt6_info *rt)
+{
+       if (rt->dst.from &&
+           dst_metrics_ptr(&rt->dst) != dst_metrics_ptr(rt->dst.from))
+               dst_init_metrics(&rt->dst, dst_metrics_ptr(rt->dst.from), true);
+}
+
 static struct dst_entry *ip6_dst_check(struct dst_entry *dst, u32 cookie)
 {
        struct rt6_info *rt;
@@ -1127,6 +1109,8 @@ static struct dst_entry *ip6_dst_check(struct dst_entry *dst, u32 cookie)
        if (rt6_check_expired(rt))
                return NULL;
 
+       rt6_dst_from_metrics_check(rt);
+
        return dst;
 }
 
@@ -1179,7 +1163,7 @@ static void ip6_rt_update_pmtu(struct dst_entry *dst, struct sock *sk,
                if (mtu < IPV6_MIN_MTU)
                        mtu = IPV6_MIN_MTU;
 
-               dst_metric_set(dst, RTAX_MTU, mtu);
+               rt6->rt6i_pmtu = mtu;
                rt6_update_expires(rt6, net->ipv6.sysctl.ip6_rt_mtu_expires);
        }
 }
@@ -1359,9 +1343,14 @@ static unsigned int ip6_default_advmss(const struct dst_entry *dst)
 
 static unsigned int ip6_mtu(const struct dst_entry *dst)
 {
+       const struct rt6_info *rt = (const struct rt6_info *)dst;
+       unsigned int mtu = rt->rt6i_pmtu;
        struct inet6_dev *idev;
-       unsigned int mtu = dst_metric_raw(dst, RTAX_MTU);
 
+       if (mtu)
+               goto out;
+
+       mtu = dst_metric_raw(dst, RTAX_MTU);
        if (mtu)
                goto out;
 
@@ -1947,12 +1936,27 @@ out:
  *     Misc support functions
  */
 
+static void rt6_set_from(struct rt6_info *rt, struct rt6_info *from)
+{
+       BUG_ON(from->dst.from);
+
+       rt->rt6i_flags &= ~RTF_EXPIRES;
+       dst_hold(&from->dst);
+       rt->dst.from = &from->dst;
+       dst_init_metrics(&rt->dst, dst_metrics_ptr(&from->dst), true);
+}
+
 static struct rt6_info *ip6_rt_copy(struct rt6_info *ort,
                                    const struct in6_addr *dest)
 {
        struct net *net = dev_net(ort->dst.dev);
-       struct rt6_info *rt = ip6_dst_alloc(net, ort->dst.dev, 0,
-                                           ort->rt6i_table);
+       struct rt6_info *rt;
+
+       if (ort->rt6i_flags & RTF_CACHE)
+               ort = (struct rt6_info *)ort->dst.from;
+
+       rt = ip6_dst_alloc(net, ort->dst.dev, 0,
+                          ort->rt6i_table);
 
        if (rt) {
                rt->dst.input = ort->dst.input;
@@ -1961,7 +1965,6 @@ static struct rt6_info *ip6_rt_copy(struct rt6_info *ort,
 
                rt->rt6i_dst.addr = *dest;
                rt->rt6i_dst.plen = 128;
-               dst_copy_metrics(&rt->dst, &ort->dst);
                rt->dst.error = ort->dst.error;
                rt->rt6i_idev = ort->rt6i_idev;
                if (rt->rt6i_idev)
@@ -2393,11 +2396,20 @@ static int rt6_mtu_change_route(struct rt6_info *rt, void *p_arg)
           PMTU discouvery.
         */
        if (rt->dst.dev == arg->dev &&
-           !dst_metric_locked(&rt->dst, RTAX_MTU) &&
-           (dst_mtu(&rt->dst) >= arg->mtu ||
-            (dst_mtu(&rt->dst) < arg->mtu &&
-             dst_mtu(&rt->dst) == idev->cnf.mtu6))) {
-               dst_metric_set(&rt->dst, RTAX_MTU, arg->mtu);
+           !dst_metric_locked(&rt->dst, RTAX_MTU)) {
+               if (rt->rt6i_flags & RTF_CACHE) {
+                       /* For RTF_CACHE with rt6i_pmtu == 0
+                        * (i.e. a redirected route),
+                        * the metrics of its rt->dst.from has already
+                        * been updated.
+                        */
+                       if (rt->rt6i_pmtu && rt->rt6i_pmtu > arg->mtu)
+                               rt->rt6i_pmtu = arg->mtu;
+               } else if (dst_mtu(&rt->dst) >= arg->mtu ||
+                          (dst_mtu(&rt->dst) < arg->mtu &&
+                           dst_mtu(&rt->dst) == idev->cnf.mtu6)) {
+                       dst_metric_set(&rt->dst, RTAX_MTU, arg->mtu);
+               }
        }
        return 0;
 }
@@ -2627,6 +2639,7 @@ static int rt6_fill_node(struct net *net,
                         int iif, int type, u32 portid, u32 seq,
                         int prefix, int nowait, unsigned int flags)
 {
+       u32 metrics[RTAX_MAX];
        struct rtmsg *rtm;
        struct nlmsghdr *nlh;
        long expires;
@@ -2740,7 +2753,10 @@ static int rt6_fill_node(struct net *net,
                        goto nla_put_failure;
        }
 
-       if (rtnetlink_put_metrics(skb, dst_metrics_ptr(&rt->dst)) < 0)
+       memcpy(metrics, dst_metrics_ptr(&rt->dst), sizeof(metrics));
+       if (rt->rt6i_pmtu)
+               metrics[RTAX_MTU - 1] = rt->rt6i_pmtu;
+       if (rtnetlink_put_metrics(skb, metrics) < 0)
                goto nla_put_failure;
 
        if (rt->rt6i_flags & RTF_GATEWAY) {