[PATCH net-next 11/15] batman-adv: tt: increase hash generation when purging clients

[Simon Wunderlich <sw@simonwunderlich.de>]

From: Sven Eckelmann <sven@narfation.org>

If batadv_tt_local_dump() is preempted during a netlink dump and resumes in
the middle of a hash bucket while batadv_tt_local_purge_pending_clients()
concurrently removes an entry, the dump offset will be shifted.

Without incrementing the hash generation counter, netlink won't set
NLM_F_DUMP_INTR and the userspace will not be informed by the inconsistent
dump..

Reported-by: Sashiko <sashiko-bot@kernel.org>
Closes: https://sashiko.dev/#/patchset/20261008-tt-avoid-unhashed-event-v2-0-7c4eed81606d@narfation.org?part=6
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>
---
 net/batman-adv/translation-table.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/batman-adv/translation-table.c b/net/batman-adv/translation-table.c
index 926b4a3214196..3ce5569a8872f 100644
--- a/net/batman-adv/translation-table.c
+++ b/net/batman-adv/translation-table.c
@@ -4454,6 +4454,7 @@ static void batadv_tt_local_purge_pending_clients(struct batadv_priv *bat_priv)
 					   batadv_print_vid(tt_common->key.vid));
 
 				hlist_del_rcu(&tt_common->hash_entry);
+				atomic_inc(&hash->generation);
 
 				/* An entry which still carries BATADV_TT_CLIENT_NEW was
 				 * never counted and must not be uncounted here.
-- 
2.47.3