Hi Simon,
Von: Simon Wunderlich sw@simonwunderlich.de An: Andreas Pape apape@phoenixcontact.com Kopie: b.a.t.m.a.n@lists.open-mesh.org Datum: 09.05.2017 17:50 Betreff: Re: [B.A.T.M.A.N.] [PATCH] batman-adv: handle race condition for claims also in batadv_bla_rx
On Friday, April 28, 2017 10:26:10 PM CEST Simon Wunderlich wrote:
From: Andreas Pape apape@phoenixcontact.com
Like in the case of the patch for batadv_bla_tx to handle a race condition when claiming a mac address for bla, a similar situation can occur when claiming is triggered via batadv_bla_rx. This patch solves this with a similar approach as for batadv_bla_tx.
Signed-off-by: Andreas Pape apape@phoenixcontact.com
Hi Andreas,
thanks again for the patch - in general, I think this looks good,
although I
don't follow completely where you saw that. Can you describe the
scenario a
little more?
We usually don't process packets from the mesh sent by nodes on the same
LAN
segment - we look at the originator and check the BLA group using batadv_check_claim_group().
There are two things which we could improve documentation-wise:
1.) Have some kernel doc batadv_tt_local_has_timed_out - we want to
have
kerneldoc for every new function we add.
Sorry, I will add that if this patch really turns out to be useful (see 2.).
2.) Describe the scenario in a comment in batadv_bla_rx(). I find the
comment
not too convincing, see above.
As in my earlier patches I use a setup which needs bla. Up to recently I experimented with batman-adv-2014.4 and I struggled a lot with looping packets. At least for version 2014.4 I found out that the patches I mailed last year where not sufficient to prevent looping packets between the mesh and the common Ethernet backbone completely under all conditions. By enabling the debugging I found that the looping packets always correlated with the claiming of devices. I got rid of the looping packets (error message from the kernel "received packet with own mac address as source address")almost completely after adding this additional patch. I now only get the kernel error message about receiving packets with own mac address sometimes when a mesh node is added to the network for very few packets which is ok for my application. But without this patch in 2014.4 I got these messages randomly during notmal operation of the network.
I have to admit that I did not retest this with the current master or version 2017.0.1. I simply integrated the patch and I can at least confirm that bla works as reliable as in the 2014.4 case with this patch. I agree that this is no proof that this patch is still really needed. I think I'll remove it from my test setup and come back with my results.
Thanks for the feedback and best regards, Andreas
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