net/ipv6: Remove expired routes with a separated list of routes.

FIB6 GC walks trees of fib6_tables to remove expired routes. Walking a tree
can be expensive if the number of routes in a table is big, even if most of
them are permanent. Checking routes in a separated list of routes having
expiration will avoid this potential issue.

Signed-off-by: Kui-Feng Lee <thinker.li@gmail.com>
Reviewed-by: David Ahern <dsahern@kernel.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 05e6f75..c9ff23c 100644 (file)
--- a/include/net/ip6_fib.h
+++ b/include/net/ip6_fib.h
@@ -179,6 +179,9 @@ struct fib6_info {
 
        refcount_t                      fib6_ref;
        unsigned long                   expires;
+
+       struct hlist_node               gc_link;
+
        struct dst_metrics              *fib6_metrics;
 #define fib6_pmtu              fib6_metrics->metrics[RTAX_MTU-1]
 
@@ -247,19 +250,6 @@ static inline bool fib6_requires_src(const struct fib6_info *rt)
        return rt->fib6_src.plen > 0;
 }
 
-static inline void fib6_clean_expires(struct fib6_info *f6i)
-{
-       f6i->fib6_flags &= ~RTF_EXPIRES;
-       f6i->expires = 0;
-}
-
-static inline void fib6_set_expires(struct fib6_info *f6i,
-                                   unsigned long expires)
-{
-       f6i->expires = expires;
-       f6i->fib6_flags |= RTF_EXPIRES;
-}
-
 static inline bool fib6_check_expired(const struct fib6_info *f6i)
 {
        if (f6i->fib6_flags & RTF_EXPIRES)
@@ -267,6 +257,11 @@ static inline bool fib6_check_expired(const struct fib6_info *f6i)
        return false;
 }
 
+static inline bool fib6_has_expires(const struct fib6_info *f6i)
+{
+       return f6i->fib6_flags & RTF_EXPIRES;
+}
+
 /* Function to safely get fn->fn_sernum for passed in rt
  * and store result in passed in cookie.
  * Return true if we can get cookie safely
@@ -388,6 +383,7 @@ struct fib6_table {
        struct inet_peer_base   tb6_peers;
        unsigned int            flags;
        unsigned int            fib_seq;
+       struct hlist_head       tb6_gc_hlist;   /* GC candidates */
 #define RT6_TABLE_HAS_DFLT_ROUTER      BIT(0)
 };
 
@@ -504,6 +500,48 @@ void fib6_gc_cleanup(void);
 
 int fib6_init(void);
 
+/* fib6_info must be locked by the caller, and fib6_info->fib6_table can be
+ * NULL.
+ */
+static inline void fib6_set_expires_locked(struct fib6_info *f6i,
+                                          unsigned long expires)
+{
+       struct fib6_table *tb6;
+
+       tb6 = f6i->fib6_table;
+       f6i->expires = expires;
+       if (tb6 && !fib6_has_expires(f6i))
+               hlist_add_head(&f6i->gc_link, &tb6->tb6_gc_hlist);
+       f6i->fib6_flags |= RTF_EXPIRES;
+}
+
+/* fib6_info must be locked by the caller, and fib6_info->fib6_table can be
+ * NULL.  If fib6_table is NULL, the fib6_info will no be inserted into the
+ * list of GC candidates until it is inserted into a table.
+ */
+static inline void fib6_set_expires(struct fib6_info *f6i,
+                                   unsigned long expires)
+{
+       spin_lock_bh(&f6i->fib6_table->tb6_lock);
+       fib6_set_expires_locked(f6i, expires);
+       spin_unlock_bh(&f6i->fib6_table->tb6_lock);
+}
+
+static inline void fib6_clean_expires_locked(struct fib6_info *f6i)
+{
+       if (fib6_has_expires(f6i))
+               hlist_del_init(&f6i->gc_link);
+       f6i->fib6_flags &= ~RTF_EXPIRES;
+       f6i->expires = 0;
+}
+
+static inline void fib6_clean_expires(struct fib6_info *f6i)
+{
+       spin_lock_bh(&f6i->fib6_table->tb6_lock);
+       fib6_clean_expires_locked(f6i);
+       spin_unlock_bh(&f6i->fib6_table->tb6_lock);
+}
+
 struct ipv6_route_iter {
        struct seq_net_private p;
        struct fib6_walker w;

diff --git a/net/ipv6/ip6_fib.c b/net/ipv6/ip6_fib.c
index bac768d..28b01a0 100644 (file)
--- a/net/ipv6/ip6_fib.c
+++ b/net/ipv6/ip6_fib.c
@@ -160,6 +160,8 @@ struct fib6_info *fib6_info_alloc(gfp_t gfp_flags, bool with_fib6_nh)
        INIT_LIST_HEAD(&f6i->fib6_siblings);
        refcount_set(&f6i->fib6_ref, 1);
 
+       INIT_HLIST_NODE(&f6i->gc_link);
+
        return f6i;
 }
 
@@ -246,6 +248,7 @@ static struct fib6_table *fib6_alloc_table(struct net *net, u32 id)
                                   net->ipv6.fib6_null_entry);
                table->tb6_root.fn_flags = RTN_ROOT | RTN_TL_ROOT | RTN_RTINFO;
                inet_peer_base_init(&table->tb6_peers);
+               INIT_HLIST_HEAD(&table->tb6_gc_hlist);
        }
 
        return table;
@@ -1057,6 +1060,8 @@ static void fib6_purge_rt(struct fib6_info *rt, struct fib6_node *fn,
                                    lockdep_is_held(&table->tb6_lock));
                }
        }
+
+       fib6_clean_expires_locked(rt);
 }
 
 /*
@@ -1118,9 +1123,10 @@ static int fib6_add_rt2node(struct fib6_node *fn, struct fib6_info *rt,
                                if (!(iter->fib6_flags & RTF_EXPIRES))
                                        return -EEXIST;
                                if (!(rt->fib6_flags & RTF_EXPIRES))
-                                       fib6_clean_expires(iter);
+                                       fib6_clean_expires_locked(iter);
                                else
-                                       fib6_set_expires(iter, rt->expires);
+                                       fib6_set_expires_locked(iter,
+                                                               rt->expires);
 
                                if (rt->fib6_pmtu)
                                        fib6_metric_set(iter, RTAX_MTU,
@@ -1479,6 +1485,10 @@ int fib6_add(struct fib6_node *root, struct fib6_info *rt,
                if (rt->nh)
                        list_add(&rt->nh_list, &rt->nh->f6i_list);
                __fib6_update_sernum_upto_root(rt, fib6_new_sernum(info->nl_net));
+
+               if (fib6_has_expires(rt))
+                       hlist_add_head(&rt->gc_link, &table->tb6_gc_hlist);
+
                fib6_start_gc(info->nl_net, rt);
        }
 
@@ -2285,9 +2295,8 @@ static void fib6_flush_trees(struct net *net)
  *     Garbage collection
  */
 
-static int fib6_age(struct fib6_info *rt, void *arg)
+static int fib6_age(struct fib6_info *rt, struct fib6_gc_args *gc_args)
 {
-       struct fib6_gc_args *gc_args = arg;
        unsigned long now = jiffies;
 
        /*
@@ -2295,7 +2304,7 @@ static int fib6_age(struct fib6_info *rt, void *arg)
         *      Routes are expired even if they are in use.
         */
 
-       if (rt->fib6_flags & RTF_EXPIRES && rt->expires) {
+       if (fib6_has_expires(rt) && rt->expires) {
                if (time_after(now, rt->expires)) {
                        RT6_TRACE("expiring %p\n", rt);
                        return -1;
@@ -2312,6 +2321,40 @@ static int fib6_age(struct fib6_info *rt, void *arg)
        return 0;
 }
 
+static void fib6_gc_table(struct net *net,
+                         struct fib6_table *tb6,
+                         struct fib6_gc_args *gc_args)
+{
+       struct fib6_info *rt;
+       struct hlist_node *n;
+       struct nl_info info = {
+               .nl_net = net,
+               .skip_notify = false,
+       };
+
+       hlist_for_each_entry_safe(rt, n, &tb6->tb6_gc_hlist, gc_link)
+               if (fib6_age(rt, gc_args) == -1)
+                       fib6_del(rt, &info);
+}
+
+static void fib6_gc_all(struct net *net, struct fib6_gc_args *gc_args)
+{
+       struct fib6_table *table;
+       struct hlist_head *head;
+       unsigned int h;
+
+       rcu_read_lock();
+       for (h = 0; h < FIB6_TABLE_HASHSZ; h++) {
+               head = &net->ipv6.fib_table_hash[h];
+               hlist_for_each_entry_rcu(table, head, tb6_hlist) {
+                       spin_lock_bh(&table->tb6_lock);
+                       fib6_gc_table(net, table, gc_args);
+                       spin_unlock_bh(&table->tb6_lock);
+               }
+       }
+       rcu_read_unlock();
+}
+
 void fib6_run_gc(unsigned long expires, struct net *net, bool force)
 {
        struct fib6_gc_args gc_args;
@@ -2327,7 +2370,7 @@ void fib6_run_gc(unsigned long expires, struct net *net, bool force)
                          net->ipv6.sysctl.ip6_rt_gc_interval;
        gc_args.more = 0;
 
-       fib6_clean_all(net, fib6_age, &gc_args);
+       fib6_gc_all(net, &gc_args);
        now = jiffies;
        net->ipv6.ip6_rt_last_gc = now;
 

diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 10751df..db10c36 100644 (file)
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -3761,10 +3761,10 @@ static struct fib6_info *ip6_route_info_create(struct fib6_config *cfg,
                rt->dst_nocount = true;
 
        if (cfg->fc_flags & RTF_EXPIRES)
-               fib6_set_expires(rt, jiffies +
-                               clock_t_to_jiffies(cfg->fc_expires));
+               fib6_set_expires_locked(rt, jiffies +
+                                       clock_t_to_jiffies(cfg->fc_expires));
        else
-               fib6_clean_expires(rt);
+               fib6_clean_expires_locked(rt);
 
        if (cfg->fc_protocol == RTPROT_UNSPEC)
                cfg->fc_protocol = RTPROT_BOOT;