diff mbox

[maint] batman-adv: fix counter for multicast supporting nodes

Message ID 1412975746-6856-1-git-send-email-linus.luessing@web.de (mailing list archive)
State Superseded, archived
Commit 33fdd2cb9fe20d90bc6bff369c9b57e849b317b6
Headers

Commit Message

Linus Lüssing Oct. 10, 2014, 9:15 p.m. UTC 
  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")

Signed-off-by: Linus Lüssing <linus.luessing@web.de>
---
 multicast.c |    8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

Comments

Linus Lüssing Oct. 11, 2014, 10:32 a.m. UTC | #1 
On Fri, Oct 10, 2014 at 11:15:46PM +0200, Linus Lüssing wrote:
> 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")
> 
> Signed-off-by: Linus Lüssing <linus.luessing@web.de>
> ---
>  multicast.c |    8 +++++---
>  1 file changed, 5 insertions(+), 3 deletions(-)

Reported-by: Tobias Hachmer <tobias@hachmer.de>
diff mbox

Patch

diff --git a/multicast.c b/multicast.c
index 96b66fd..02c2e0c 100644
--- a/multicast.c
+++ b/multicast.c
@@ -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;
 	}