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Date: Wed, 24 Jun 2015 21:05:02 +0200
From: Antonio Quartulli <antonio@meshcoding.com>
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Subject: Re: [B.A.T.M.A.N.] [PATCH maint 1/2] batman-adv: initialize up/down
 values when adding a gateway
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To: The list for a Better Approach To Mobile Ad-hoc Networking <b.a.t.m.a.n@lists.open-mesh.org>
Cc: Simon Wunderlich <simon@open-mesh.com>

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Nice catch!

On 24/06/15 14:50, Simon Wunderlich wrote:
> From: Simon Wunderlich <simon@open-mesh.com>
>=20
> Without this initialization, gateways which actually announce up/down
> bandwidth of 0/0 could be added. If these nodes get purged later, the

as clarified on IRC here Simon was referring to the orig_node purge
routine (_batadv_purge_orig()) that calls batadv_gw_node_delete().

> gw_node structure does not get removed since batadv_gw_node_delete()
> updates the gw_node with up/down bandwidth of 0/0, and the updating
> function then discards the change and does not free gw_node.
>=20

I have witnessed situations where nodes in the mesh receive GW TVLV
with bandwidth 0/0 even if it shouldn't be such. Therefore the situation
scenario described by Simon is more likely than what one might think.

I also think that we should investigate why we see this 0/0 announcement
when we should not. But this is for another thread ;)

> This results in leaking the gw_node structures, which references other
> structures: gw_node -> orig_node -> orig_node_ifinfo -> hardif. When
> removing the interface later, the open reference on the hardif may caus=
e
> hangs with the infamous "unregister_netdevice: waiting for mesh1 to
> become free. Usage count =3D 1" message.
>=20
> Signed-off-by: Simon Wunderlich <simon@open-mesh.com>

Acked-by: Antonio Quartulli <antonio@meshcoding.com>

Good job!

--=20
Antonio Quartulli


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