ipv6: remove rt6i_genid

Eric Dumazet noticed that all no-nonexthop or no-gateway routes which
are already marked DST_HOST (e.g. input routes routes) will always be
invalidated during sk_dst_check. Thus per-socket dst caching absolutely
had no effect and early demuxing had no effect.

Thus this patch removes rt6i_genid: fn_sernum already gets modified during
add operations, so we only must ensure we mutate fn_sernum during ipv6
address remove operations. This is a fairly cost extensive operations,
but address removal should not happen that often. Also our mtu update
functions do the same and we heard no complains so far. xfrm policy
changes also cause a call into fib6_flush_trees. Also plug a hole in
rt6_info (no cacheline changes).

I verified via tracing that this change has effect.

Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: YOSHIFUJI Hideaki <hideaki@yoshifuji.org>
Cc: Vlad Yasevich <vyasevich@gmail.com>
Cc: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Cc: Martin Lau <kafai@fb.com>
Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/net/ip6_fib.h b/include/net/ip6_fib.h
index 9bcb220bd4ad13538ed0ee2d51546b1463cd116b..cf485f9aa56369fec2d47d82ca0cb5741ffca30e 100644 (file)
--- a/include/net/ip6_fib.h
+++ b/include/net/ip6_fib.h
@@ -114,16 +114,13 @@ struct rt6_info {
        u32                             rt6i_flags;
        struct rt6key                   rt6i_src;
        struct rt6key                   rt6i_prefsrc;
-       u32                             rt6i_metric;
 
        struct inet6_dev                *rt6i_idev;
        unsigned long                   _rt6i_peer;
 
-       u32                             rt6i_genid;
-
+       u32                             rt6i_metric;
        /* more non-fragment space at head required */
        unsigned short                  rt6i_nfheader_len;
-
        u8                              rt6i_protocol;
 };
 

diff --git a/include/net/net_namespace.h b/include/net/net_namespace.h
index 361d26077196678af5bd7ce217715a2cc847f2af..e0d64667a4b3e3be0cb9f70d45f02988fc19b21f 100644 (file)
--- a/include/net/net_namespace.h
+++ b/include/net/net_namespace.h
@@ -352,26 +352,12 @@ static inline void rt_genid_bump_ipv4(struct net *net)
        atomic_inc(&net->ipv4.rt_genid);
 }
 
-#if IS_ENABLED(CONFIG_IPV6)
-static inline int rt_genid_ipv6(struct net *net)
-{
-       return atomic_read(&net->ipv6.rt_genid);
-}
-
-static inline void rt_genid_bump_ipv6(struct net *net)
-{
-       atomic_inc(&net->ipv6.rt_genid);
-}
-#else
-static inline int rt_genid_ipv6(struct net *net)
-{
-       return 0;
-}
-
+extern void (*__fib6_flush_trees)(struct net *net);
 static inline void rt_genid_bump_ipv6(struct net *net)
 {
+       if (__fib6_flush_trees)
+               __fib6_flush_trees(net);
 }
-#endif
 
 #if IS_ENABLED(CONFIG_IEEE802154_6LOWPAN)
 static inline struct netns_ieee802154_lowpan *

diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index 3342ee64f2e3f137a7a44dda5b006ad24da87117..3e118dfddd02a0c16051b49ffba0953daed54225 100644 (file)
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -4780,10 +4780,11 @@ static void __ipv6_ifa_notify(int event, struct inet6_ifaddr *ifp)
 
                if (ip6_del_rt(ifp->rt))
                        dst_free(&ifp->rt->dst);
+
+               rt_genid_bump_ipv6(net);
                break;
        }
        atomic_inc(&net->ipv6.dev_addr_genid);
-       rt_genid_bump_ipv6(net);
 }
 
 static void ipv6_ifa_notify(int event, struct inet6_ifaddr *ifp)

diff --git a/net/ipv6/addrconf_core.c b/net/ipv6/addrconf_core.c
index e6960457f62582c4ca41c674cc531d64ca76b038..98cc4cd570e23b96dc479956afe7bb6660a8a6c6 100644 (file)
--- a/net/ipv6/addrconf_core.c
+++ b/net/ipv6/addrconf_core.c
@@ -8,6 +8,13 @@
 #include <net/addrconf.h>
 #include <net/ip.h>
 
+/* if ipv6 module registers this function is used by xfrm to force all
+ * sockets to relookup their nodes - this is fairly expensive, be
+ * careful
+ */
+void (*__fib6_flush_trees)(struct net *);
+EXPORT_SYMBOL(__fib6_flush_trees);
+
 #define IPV6_ADDR_SCOPE_TYPE(scope)    ((scope) << 16)
 
 static inline unsigned int ipv6_addr_scope2type(unsigned int scope)

diff --git a/net/ipv6/ip6_fib.c b/net/ipv6/ip6_fib.c
index 76b7f5ee8f4c8a9d8e2b0369135e83d067a31afa..97b9fa8de37783a0da90671208e42a887a20332c 100644 (file)
--- a/net/ipv6/ip6_fib.c
+++ b/net/ipv6/ip6_fib.c
@@ -1605,6 +1605,24 @@ static void fib6_prune_clones(struct net *net, struct fib6_node *fn)
        fib6_clean_tree(net, fn, fib6_prune_clone, 1, NULL);
 }
 
+static int fib6_update_sernum(struct rt6_info *rt, void *arg)
+{
+       __u32 sernum = *(__u32 *)arg;
+
+       if (rt->rt6i_node &&
+           rt->rt6i_node->fn_sernum != sernum)
+               rt->rt6i_node->fn_sernum = sernum;
+
+       return 0;
+}
+
+static void fib6_flush_trees(struct net *net)
+{
+       __u32 new_sernum = fib6_new_sernum();
+
+       fib6_clean_all(net, fib6_update_sernum, &new_sernum);
+}
+
 /*
  *     Garbage collection
  */
@@ -1788,6 +1806,8 @@ int __init fib6_init(void)
                              NULL);
        if (ret)
                goto out_unregister_subsys;
+
+       __fib6_flush_trees = fib6_flush_trees;
 out:
        return ret;
 

diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index f23fbd28a501ed5c3438abb7f1cbbec85233688b..bafde82324c57369abfd6f5b37decafadcb08d9c 100644 (file)
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -314,7 +314,6 @@ static inline struct rt6_info *ip6_dst_alloc(struct net *net,
 
                memset(dst + 1, 0, sizeof(*rt) - sizeof(*dst));
                rt6_init_peer(rt, table ? &table->tb6_peers : net->ipv6.peers);
-               rt->rt6i_genid = rt_genid_ipv6(net);
                INIT_LIST_HEAD(&rt->rt6i_siblings);
        }
        return rt;
@@ -1098,9 +1097,6 @@ static struct dst_entry *ip6_dst_check(struct dst_entry *dst, u32 cookie)
         * DST_OBSOLETE_FORCE_CHK which forces validation calls down
         * into this function always.
         */
-       if (rt->rt6i_genid != rt_genid_ipv6(dev_net(rt->dst.dev)))
-               return NULL;
-
        if (!rt->rt6i_node || (rt->rt6i_node->fn_sernum != cookie))
                return NULL;