[PATCH net-next 14/15] batman-adv: tt: don't uncount never committed clients on pending purge

[Simon Wunderlich <sw@simonwunderlich.de>]

From: Sven Eckelmann <sven@narfation.org>

batadv_tt_local_purge_pending_clients() decreases vlan->tt.num_entries for
every entry it unlinks, but an entry which still carries
BATADV_TT_CLIENT_NEW was never counted by batadv_tt_local_transition_new().

batadv_tt_local_resize_to_mtu() calls batadv_tt_local_purge() and
batadv_tt_local_purge_pending_clients() directly, without committing in
between, and it halves its timeout down towards zero. Once the timeout is
short enough, batadv_tt_local_purge_list() marks even freshly added clients
as pending. And each of them decreases a counter it never increased.

Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>
---
 net/batman-adv/translation-table.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/net/batman-adv/translation-table.c b/net/batman-adv/translation-table.c
index a870d9a97e329..794692170b611 100644
--- a/net/batman-adv/translation-table.c
+++ b/net/batman-adv/translation-table.c
@@ -349,6 +349,10 @@ static void batadv_tt_local_size_inc(struct batadv_priv *bat_priv,
  *  given vid
  * @bat_priv: the bat priv with all the mesh interface information
  * @vid: the VLAN identifier
+ *
+ * It must only be called after a batadv_tt_local_entry without NEW flag
+ * was removed from bat_priv->tt.local_hash (under the specific
+ * list_locks[i]).
  */
 static void batadv_tt_local_size_dec(struct batadv_priv *bat_priv,
 				     unsigned short vid)
@@ -4019,8 +4023,13 @@ static void batadv_tt_local_purge_pending_clients(struct batadv_priv *bat_priv)
 					   tt_common->addr,
 					   batadv_print_vid(tt_common->vid));
 
-				batadv_tt_local_size_dec(bat_priv, tt_common->vid);
 				hlist_del_rcu(&tt_common->hash_entry);
+
+				/* An entry which still carries BATADV_TT_CLIENT_NEW was
+				 * never counted and must not be uncounted here.
+				 */
+				if (!(tt_common->flags & BATADV_TT_CLIENT_NEW))
+					batadv_tt_local_size_dec(bat_priv, tt_common->vid);
 			}
 
 			if (cont)
-- 
2.47.3