RE: [PATCH bpf-next 5/8] xdp: add xdp_do_redirect_frame() for pre-computed xdp_frames

["Toke Høiland-Jørgensen" <toke@redhat.com>]

John Fastabend <john.fastabend@gmail.com> writes:

> Toke Høiland-Jørgensen wrote:
>> Add an xdp_do_redirect_frame() variant which supports pre-computed
>> xdp_frame structures. This will be used in bpf_prog_run() to avoid having
>> to write to the xdp_frame structure when the XDP program doesn't modify the
>> frame boundaries.
>> 
>> Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
>> ---
>>  include/linux/filter.h |  4 ++++
>>  net/core/filter.c      | 28 +++++++++++++++++++++-------
>>  2 files changed, 25 insertions(+), 7 deletions(-)
>> 
>> diff --git a/include/linux/filter.h b/include/linux/filter.h
>> index b6a216eb217a..845452c83e0f 100644
>> --- a/include/linux/filter.h
>> +++ b/include/linux/filter.h
>> @@ -1022,6 +1022,10 @@ int xdp_do_generic_redirect(struct net_device *dev, struct sk_buff *skb,
>>  int xdp_do_redirect(struct net_device *dev,
>>  		    struct xdp_buff *xdp,
>>  		    struct bpf_prog *prog);
>> +int xdp_do_redirect_frame(struct net_device *dev,
>> +			  struct xdp_buff *xdp,
>> +			  struct xdp_frame *xdpf,
>> +			  struct bpf_prog *prog);
>
> I don't really like that we are passing both the xdp_buff ptr and
> xdp_frame *xdpf around when one is always null it looks like?

Yeah, the problem is basically that AF_XDP uses xdp_buff all the way
through, so we can't pass xdp_frame to that. I do agree that it's a bit
ugly, though; maybe we can just do the XSK disambiguation in the caller;
will take another look at this - thanks!

-Toke