On 8/20/20 2:25 AM, Jesper Dangaard Brouer wrote:
>>> diff --git a/net/core/dev.c b/net/core/dev.c
>>> index a00aa737ce29..1f85880ee412 100644
>>> --- a/net/core/dev.c
>>> +++ b/net/core/dev.c
>>> @@ -8747,9 +8747,9 @@ static enum bpf_xdp_mode dev_xdp_mode(u32 flags)
>>> {
>>> if (flags & XDP_FLAGS_HW_MODE)
>>> return XDP_MODE_HW;
>>> - if (flags & XDP_FLAGS_DRV_MODE)
>>> - return XDP_MODE_DRV;
>>> - return XDP_MODE_SKB;
>>> + if (flags & XDP_FLAGS_SKB_MODE)
>>> + return XDP_MODE_SKB;
>>> + return XDP_MODE_DRV;
>>> }
>>>
>>
>> I think the better way would be to choose XDP_MODE_DRV if ndo_bpf !=
>> NULL and XDP_MODE_SKB otherwise. That seems to be matching original
>> behavior, no?
>
> Yes, but this silent fallback to XDP_MODE_SKB (generic-XDP) have
> cause a lot of support issues in the past. I wish we could change it.
> We already changed all the samples/bpf/ to ask for XDP_FLAGS_DRV_MODE,
> so they behave this way.
>
I would prefer the flags check in Lorenzo's proposed patch which is an
explicit opt in to the SKB mode.
