batman-adv: fix counter for multicast supporting nodes
PATCH 1/1 batman-adv: fix counter for multicast supporting nodes
A miscounting of nodes having multicast optimizations enabled can lead to multicast packet loss in the following scenario:
If the first OGM a node receives from another one has no multicast optimizations support (no multicast tvlv) then we are missing to increase the counter. This potentially leads to the wrong assumption that we could safely use multicast optimizations.
Fixings this by increasing the counter if the initial OGM has the multicast TVLV unset, too.
Introduced by 77ec494490d60d89b42cd01d5dbf8dee04503623 ("batman-adv: Announce new capability via multicast TVLV")
--- multicast.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-)
multicast.c +5 -3
@@ -686,11 +686,13 @@ static void batadv_mcast_tvlv_ogm_handler_v1(struct batadv_priv *bat_priv,if (orig_initialized)atomic_dec (&bat_priv->mcast.num_disabled); orig->capabilities |=BATADV_ORIG_CAPA_HAS_MCAST ; -/* If mcast support is being switched off increase the disabled -* mcast node counter. +/* If mcast support is being switched off or if this is an initial +* OGM without mcast support then increase the disabled mcast +* node counter. */ }else if (!orig_mcast_enabled && - orig->capabilities &BATADV_ORIG_CAPA_HAS_MCAST ) { + (orig->capabilities &BATADV_ORIG_CAPA_HAS_MCAST || + !orig_initialized)) {atomic_inc (&bat_priv->mcast.num_disabled); orig->capabilities &= ~BATADV_ORIG_CAPA_HAS_MCAST ; }
Signature · 1 line
1.7.10.4
Quoted 11 lines · Linus Lüssing
A miscounting of nodes having multicast optimizations enabled can lead to multicast packet loss in the following scenario:
If the first OGM a node receives from another one has no multicast optimizations support (no multicast tvlv) then we are missing to increase the counter. This potentially leads to the wrong assumption that we could safely use multicast optimizations.
Fixings this by increasing the counter if the initial OGM has the multicast TVLV unset, too.
Quoted 7 lines
Introduced by
77ec494490d60d89b42cd01d5dbf8dee04503623("batman-adv: Announce new capability via multicast TVLV")Signed-off-by Linus Lüssing <[email protected]>--- multicast.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-)