Re: [B.A.T.M.A.N.] [PATCH] batman-adv: Add multicast optimization support for bridged setups

[Marek Lindner <mareklindner@neomailbox.ch>]

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On Wednesday 18 June 2014 00:24:14 Linus Lüssing wrote:
> A batman-adv node needs to know on/behind which other batman-adv
> node a multicast listener exists to be able to know where it needs
> to forward multicast packets to. A multicast listener can either
> sit on bat0, on a bridge on top of bat0. Or in this case, that's
> what "mla_bridge_get" is for, behind the bridge.
> 
> We usually don't have direct access to the kernel of weird Windows
> machines behind a bridge. Luckily a protocol, Multicast Listener
> Discovery, exists to detect such multicast listeners.
> 
> The bridge code has multicast snooping already, so it already
> memorizes what multicast listeners it has behind it's bridge.
> That's what we are fetching here. To add these to our local TT to
> announce them through the mesh.

Thanks for the clarifications but that does not address my question. To be 
more precise: In batadv_mcast_mla_update() your code is calling 
batadv_mcast_mla_softif_get() which queries the bridge interface (if bridged). 
A couple of lines later batadv_mcast_mla_bridge_get() is called (if bridged). 
It looks to me the code queries the bridge twice ?

Then, I am comparing the kernel doc to get the difference but I see none:

 * batadv_mcast_mla_softif_get - get softif multicast listeners
 * @dev: the device to collect multicast addresses from
 * @mcast_list: a list to put found addresses into
 *
 * Collect multicast addresses of the local multicast listeners
 * on the given soft interface, dev, in the given mcast_list.
 *
 * If there is a bridge interface on top of dev, collect from that one
 * instead.

 ===============================================================

 * batadv_mcast_mla_bridge_get - get bridged-in multicast listeners
 * @dev: a bridge slave whose bridge to collect multicast addresses from
 * @mcast_list: a list to put found addresses into
 *
 * Collects multicast addresses of the bridged-in multicast listeners
 * from the bridge on top of the given soft interface, dev, in the
 * given mcast_list.

What is the difference between these calls and why doesn't the code explain 
that difference ?

Cheers,
Marek

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