ipv4: Handle route deletion notification

When a route is deleted we potentially need to promote the next route in
the FIB alias list (e.g., with an higher metric). In case we find such a
route, a replace notification is emitted. Otherwise, a delete
notification for the deleted route.

v2:
* Convert to use fib_find_alias() instead of fib_find_first_alias()

Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Reviewed-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv4/fib_trie.c b/net/ipv4/fib_trie.c
index f56945d00d7acc093420a5c3ae95c4df437b6af0..012aca433a913764505d780440d07b74467808b0 100644 (file)
--- a/net/ipv4/fib_trie.c
+++ b/net/ipv4/fib_trie.c
@@ -1570,6 +1570,36 @@ static void fib_remove_alias(struct trie *t, struct key_vector *tp,
        node_pull_suffix(tp, fa->fa_slen);
 }
 
+static void fib_notify_alias_delete(struct net *net, u32 key,
+                                   struct hlist_head *fah,
+                                   struct fib_alias *fa_to_delete,
+                                   struct netlink_ext_ack *extack)
+{
+       struct fib_alias *fa_next, *fa_to_notify;
+       u32 tb_id = fa_to_delete->tb_id;
+       u8 slen = fa_to_delete->fa_slen;
+       enum fib_event_type fib_event;
+
+       /* Do not notify if we do not care about the route. */
+       if (fib_find_alias(fah, slen, 0, 0, tb_id, true) != fa_to_delete)
+               return;
+
+       /* Determine if the route should be replaced by the next route in the
+        * list.
+        */
+       fa_next = hlist_entry_safe(fa_to_delete->fa_list.next,
+                                  struct fib_alias, fa_list);
+       if (fa_next && fa_next->fa_slen == slen && fa_next->tb_id == tb_id) {
+               fib_event = FIB_EVENT_ENTRY_REPLACE_TMP;
+               fa_to_notify = fa_next;
+       } else {
+               fib_event = FIB_EVENT_ENTRY_DEL_TMP;
+               fa_to_notify = fa_to_delete;
+       }
+       call_fib_entry_notifiers(net, fib_event, key, KEYLENGTH - slen,
+                                fa_to_notify, extack);
+}
+
 /* Caller must hold RTNL. */
 int fib_table_delete(struct net *net, struct fib_table *tb,
                     struct fib_config *cfg, struct netlink_ext_ack *extack)
@@ -1623,6 +1653,7 @@ int fib_table_delete(struct net *net, struct fib_table *tb,
        if (!fa_to_delete)
                return -ESRCH;
 
+       fib_notify_alias_delete(net, key, &l->leaf, fa_to_delete, extack);
        call_fib_entry_notifiers(net, FIB_EVENT_ENTRY_DEL, key, plen,
                                 fa_to_delete, extack);
        rtmsg_fib(RTM_DELROUTE, htonl(key), fa_to_delete, plen, tb->tb_id,