From: "Linus Lüssing" <linus.luessing@c0d3.blue>
To: The list for a Better Approach To Mobile Ad-hoc Networking
<b.a.t.m.a.n@lists.open-mesh.org>
Subject: Re: [B.A.T.M.A.N.] [PATCH maint v2 1/2] batman-adv: fix packet checksum in receive path
Date: Tue, 23 Jan 2018 12:46:51 +0100 [thread overview]
Message-ID: <20180123114651.GC23784@otheros> (raw)
In-Reply-To: <05cee97344804ffb2a8df87603663a098fd0cb36.1516701590.git.mschiffer@universe-factory.net>
On Tue, Jan 23, 2018 at 10:59:49AM +0100, Matthias Schiffer wrote:
> eth_type_trans() internally calls skb_pull(), which does not adjust the
> skb checksum; skb_postpull_rcsum() is necessary to avoid log spam of the
> form "bat0: hw csum failure" when packets with CHECKSUM_COMPLETE are
> received.
>
> Note that in usual setups, packets don't reach batman-adv with
> CHECKSUM_COMPLETE (I assume NICs bail out of checksumming when they see
> batadv's ethtype?), which is why the log messages do nor occur on every
> system using batman-adv. I could reproduce this issue by stacking
> batman-adv on top of a VXLAN interface.
>
> Signed-off-by: Matthias Schiffer <mschiffer@universe-factory.net>
Seems reasonable, this change.
I'm just a little confused though: Two years ago someone had reported
checksumming errors with a Raspberry Pi and batman-adv:
https://www.open-mesh.org/issues/224
And they seemed to be gone in newer kernel versions, while hardware
checksumming was supposedly still enabled.
Are the issues reproduceable without using VXLANs (for instance on
a Pi1 or Pi2)? Are they reproduceable on a recent kernel version?
(I guess you tested with a 4.4 kernel?)
Regards, Linus
next prev parent reply other threads:[~2018-01-23 11:46 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-23 9:59 [B.A.T.M.A.N.] [PATCH maint v2 1/2] batman-adv: fix packet checksum in receive path Matthias Schiffer
2018-01-23 9:59 ` [B.A.T.M.A.N.] [PATCH maint v2 2/2] batman-adv: invalidate checksum on fragment reassembly Matthias Schiffer
2018-01-23 11:46 ` Linus Lüssing [this message]
2018-01-23 12:21 ` [B.A.T.M.A.N.] [PATCH maint v2 1/2] batman-adv: fix packet checksum in receive path Sven Eckelmann
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