Subject: Re: [PATCH bpf-next] bpf: devmap: move drop error path to devmap for XDP_REDIRECT

From: Lorenzo Bianconi <[email-masked]>
Date: Sat, 27 Feb 2021 11:16:33 +0100

> On 2/17/21 2:56 PM, Lorenzo Bianconi wrote:
> > We want to change the current ndo_xdp_xmit drop semantics because
> > it will allow us to implement better queue overflow handling.
> > This is working towards the larger goal of a XDP TX queue-hook.
> > Move XDP_REDIRECT error path handling from each XDP ethernet driver to
> > devmap code. According to the new APIs, the driver running the
> > ndo_xdp_xmit pointer, will break tx loop whenever the hw reports a tx
> > error and it will just return to devmap caller the number of successfully
> > transmitted frames. It will be devmap responsability to free dropped frames.
> > Move each XDP ndo_xdp_xmit capable driver to the new APIs:
> > - veth
> > - virtio-net
> > - mvneta
> > - mvpp2
> > - socionext
> > - amazon ena
> > - bnxt
> > - freescale (dpaa2, dpaa)
> > - xen-frontend
> > - qede
> > - ice
> > - igb
> > - ixgbe
> > - i40e
> > - mlx5
> > - ti (cpsw, cpsw-new)
> > - tun
> > - sfc
> 
> I presume for a number of these drivers the refactoring changes were just compile-
> tested due to lack of HW, right? If so, please also Cc related driver maintainers
> aside from the few of us, so they have a chance to review & ACK the patch if it looks
> good to them. I presume Ed saw it by accident, but for others it might easily get
> lost in the daily mail flood.

Hi Daniel,

ack, I will do in v2.

> 
> > More details about the new ndo_xdp_xmit design can be found here [0].
> > 
> > [0] https://github.com/xdp-project/xdp-project/blob/master/areas/core/redesign01_ndo_xdp_xmit.org
> 
> I'd probably move this below the "---" if it's not essential to the commit itself or
> rather take relevant parts out and move it into the commit desc so it doesn't get
> lost for future ref given things could likely reschuffle inside the repo in the future,
> just a nit.

ack, I will do in v2.

Regards,
Lorenzo

> 
> > Signed-off-by: Lorenzo Bianconi <[email-masked]>