[PATCH batadv v2 6/6] batman-adv: tt: don't uncount never committed clients on pending purge

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.

Consume the BATADV_TT_CLIENT_NEW accounting token here as well, so that the
counter is only decreased for entries which were actually counted.

Signed-off-by: Sven Eckelmann <[email protected]>
---
 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 28575051..a0ac7899 100644
--- a/net/batman-adv/translation-table.c
+++ b/net/batman-adv/translation-table.c
@@ -4013,6 +4013,7 @@ static void batadv_tt_local_purge_pending_clients(struct batadv_priv *bat_priv)
 	struct batadv_tt_local_entry *tt_local;
 	struct hlist_node *node_tmp;
 	struct hlist_head *head;
+	u16 old_flags;
 	u32 i;
 
 	if (!hash)
@@ -4033,8 +4034,16 @@ 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.
+			 */
+			old_flags = atomic_fetch_andnot(BATADV_TT_CLIENT_NEW,
+							&tt_common->flags);
+			if (!(old_flags & BATADV_TT_CLIENT_NEW))
+				batadv_tt_local_size_dec(bat_priv, tt_common->vid);
+
 			tt_local = container_of(tt_common,
 						struct batadv_tt_local_entry,
 						common);

-- 
2.47.3