10 May
2017
10 May
'17
5:45 a.m.
Hi Simon,
Von: Simon Wunderlich <sw(a)simonwunderlich.de>
An: Andreas Pape <apape(a)phoenixcontact.com>
Kopie: b.a.t.m.a.n(a)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:
although I
From: Andreas Pape
<apape(a)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(a)phoenixcontact.com>
Hi Andreas,
thanks again for the patch - in general, I think this looks good, 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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