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