Re: [virtio-dev] Re: [PATCH v9] virtio-net: support inner header hash

[Jason Wang <jasowang@redhat.com>]

On Thu, Mar 2, 2023 at 4:10âPM Michael S. Tsirkin <mst@redhat.com> wrote:
>
> On Thu, Mar 02, 2023 at 03:57:10PM +0800, Jason Wang wrote:
> > Kernel had already used the eBPF program for hashing, classifying
> > various types of eBPF program other than XDP/socket filter
> > (pass/drop).
> >
> > Thanks
>
> where is it used for hashing?

I can see it is used by team/lb:

static unsigned int lb_get_skb_hash(struct lb_priv *lb_priv,
                                    struct sk_buff *skb)
{
        struct bpf_prog *fp;
        uint32_t lhash;
        unsigned char *c;

        fp = rcu_dereference_bh(lb_priv->fp);
        if (unlikely(!fp))
                return 0;
        lhash = bpf_prog_run(fp, skb);
        c = (char *) &lhash;
        return c[0] ^ c[1] ^ c[2] ^ c[3];
}

But the point is that the return value is determined by the prog type
(or the context).

Thanks

>
> --
> MST
>
>
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