Re: [PATCH net-next v2 1/3] net/sched: Introduce action hash

Cong Wang
2020-07-02T20:52:52Z

On Wed, Jul 1, 2020 at 11:47 AM Ariel Levkovich <lariel@mellanox.com> wrote:
>
> Allow setting a hash value to a packet for a future match.
>
> The action will determine the packet's hash result according to
> the selected hash type.
>
> The first option is to select a basic asymmetric l4 hash calculation
> on the packet headers which will either use the skb->hash value as
> if such was already calculated and set by the device driver, or it
> will perform the kernel jenkins hash function on the packet which will
> generate the result otherwise.
>
> The other option is for user to provide an BPF program which is
> dedicated to calculate the hash. In such case the program is loaded
> and used by tc to perform the hash calculation and provide it to
> the hash action to be stored in skb->hash field.
>
> The BPF option can be useful for future HW offload support of the hash
> calculation by emulating the HW hash function when it's different than
> the kernel's but yet we want to maintain consistency between the SW and
> the HW.

In previous discussion, people mentioned act_skbedit. If you have
a legitimate reason for adding a new action instead of simply extending
act_skbedit, you have to mention it here or in the cover letter.

Thanks.