On Fri, Dec 15, 2017 at 1:23 PM, Sven Eckelmann sven.eckelmann@openmesh.com wrote:

Hi,

we are currently starting to use batman-adv as mesh protocol on multicore embedded devices. These usually don't have a lot of CPU power per core but are reasonable fast when using multiple cores.

It was noticed that sending was working very well but receiving was basically only using on CPU core per neighbor. The reason for that is format of the (normal) incoming packet:

+--------------------+ | ip(v6)hdr | +--------------------+ | inner ethhdr | +--------------------+ | batadv unicast hdr | +--------------------+ | outer ethhdr | +--------------------+

The flow dissector will therefore stop after parsing the outer ethernet header and will not parse the actual ipv(4|6)/... header of the packet. Our assumption was now that it would help us to add minimal support to the flow dissector to jump over the batman-adv unicast and inner ethernet header (like in gre ETH_P_TEB). The patch was implemented in a slightly hacky way [1] and the results looked quite promising.

I didn't get any feedback how the files should actually be named and I am not really happy with the current names - so please feel free to propose better names.

The discussion of the RFC v2 can be found in the related patches of https://patchwork.ozlabs.org/cover/844783/

Changes in v3:

• removed change of uapi/linux/batman_adv.h to uapi/linux/batadv_genl.h
  • requested by Willem de Bruijn willemdebruijn.kernel@gmail.com
• removed naming fixes for enums/defines in uapi/linux/batadv_genl.h
  • requested by Willem de Bruijn willemdebruijn.kernel@gmail.com
• renamed uapi/linux/batadv.h to uapi/linux/batadv_packet.h
• moved batadv dissector functionality in own function
  • requested by Tom Herbert tom@herbertland.com
• added support for flags FLOW_DISSECTOR_F_STOP_AT_ENCAP and FLOW_DIS_ENCAPSULATION
  • requested by Willem de Bruijn willemdebruijn.kernel@gmail.com

Thanks for making these changes. The flow dissection looks good to me.

One possible issue is that this exposes kernel fixed width types u8/u16/.. to userspace. For posix compatibility reasons, uapi headers use the variant with underscores.