[xdp-hints] Re: [PATCH bpf-next v2 6/8] mlx4: Introduce mlx4_xdp_buff wrapper for xdp_buff

[Stanislav Fomichev <sdf@google.com>]

On Tue, Nov 22, 2022 at 5:49 AM Tariq Toukan <ttoukan.linux@gmail.com> wrote:
>
>
>
> On 11/21/2022 8:25 PM, Stanislav Fomichev wrote:
> > No functional changes. Boilerplate to allow stuffing more data after xdp_buff.
> >
> > Cc: Tariq Toukan <tariqt@nvidia.com>
> > Cc: John Fastabend <john.fastabend@gmail.com>
> > Cc: David Ahern <dsahern@gmail.com>
> > Cc: Martin KaFai Lau <martin.lau@linux.dev>
> > Cc: Jakub Kicinski <kuba@kernel.org>
> > Cc: Willem de Bruijn <willemb@google.com>
> > Cc: Jesper Dangaard Brouer <brouer@redhat.com>
> > Cc: Anatoly Burakov <anatoly.burakov@intel.com>
> > Cc: Alexander Lobakin <alexandr.lobakin@intel.com>
> > Cc: Magnus Karlsson <magnus.karlsson@gmail.com>
> > Cc: Maryam Tahhan <mtahhan@redhat.com>
> > Cc: xdp-hints@xdp-project.net
> > Cc: netdev@vger.kernel.org
> > Signed-off-by: Stanislav Fomichev <sdf@google.com>
> > ---
> >   drivers/net/ethernet/mellanox/mlx4/en_rx.c | 26 +++++++++++++---------
> >   1 file changed, 15 insertions(+), 11 deletions(-)
> >
> > diff --git a/drivers/net/ethernet/mellanox/mlx4/en_rx.c b/drivers/net/ethernet/mellanox/mlx4/en_rx.c
> > index 8f762fc170b3..467356633172 100644
> > --- a/drivers/net/ethernet/mellanox/mlx4/en_rx.c
> > +++ b/drivers/net/ethernet/mellanox/mlx4/en_rx.c
> > @@ -661,17 +661,21 @@ static int check_csum(struct mlx4_cqe *cqe, struct sk_buff *skb, void *va,
> >   #define MLX4_CQE_STATUS_IP_ANY (MLX4_CQE_STATUS_IPV4)
> >   #endif
> >
> > +struct mlx4_xdp_buff {
> > +     struct xdp_buff xdp;
> > +};
> > +
> >   int mlx4_en_process_rx_cq(struct net_device *dev, struct mlx4_en_cq *cq, int budget)
> >   {
> >       struct mlx4_en_priv *priv = netdev_priv(dev);
> >       int factor = priv->cqe_factor;
> >       struct mlx4_en_rx_ring *ring;
> > +     struct mlx4_xdp_buff this would helpmxbuf;
>
> as it doesn't go through an init function (only mxbuf.xdp does), better
> init to zero.

SG, will do, thanks!

> >       struct bpf_prog *xdp_prog;
> >       int cq_ring = cq->ring;
> >       bool doorbell_pending;
> >       bool xdp_redir_flush;
> >       struct mlx4_cqe *cqe;
> > -     struct xdp_buff xdp;
> >       int polled = 0;
> >       int index;
> >
> > @@ -681,7 +685,7 @@ int mlx4_en_process_rx_cq(struct net_device *dev, struct mlx4_en_cq *cq, int bud
> >       ring = priv->rx_ring[cq_ring];
> >
> >       xdp_prog = rcu_dereference_bh(ring->xdp_prog);
> > -     xdp_init_buff(&xdp, priv->frag_info[0].frag_stride, &ring->xdp_rxq);
> > +     xdp_init_buff(&mxbuf.xdp, priv->frag_info[0].frag_stride, &ring->xdp_rxq);
> >       doorbell_pending = false;
> >       xdp_redir_flush = false;
> >
> > @@ -776,24 +780,24 @@ int mlx4_en_process_rx_cq(struct net_device *dev, struct mlx4_en_cq *cq, int bud
> >                                               priv->frag_info[0].frag_size,
> >                                               DMA_FROM_DEVICE);
> >
> > -                     xdp_prepare_buff(&xdp, va - frags[0].page_offset,
> > +                     xdp_prepare_buff(&mxbuf.xdp, va - frags[0].page_offset,
> >                                        frags[0].page_offset, length, false);
> > -                     orig_data = xdp.data;
> > +                     orig_data = mxbuf.xdp.data;
> >
> > -                     act = bpf_prog_run_xdp(xdp_prog, &xdp);
> > +                     act = bpf_prog_run_xdp(xdp_prog, &mxbuf.xdp);
> >
> > -                     length = xdp.data_end - xdp.data;
> > -                     if (xdp.data != orig_data) {
> > -                             frags[0].page_offset = xdp.data -
> > -                                     xdp.data_hard_start;
> > -                             va = xdp.data;
> > +                     length = mxbuf.xdp.data_end - mxbuf.xdp.data;
> > +                     if (mxbuf.xdp.data != orig_data) {
> > +                             frags[0].page_offset = mxbuf.xdp.data -
> > +                                     mxbuf.xdp.data_hard_start;
> > +                             va = mxbuf.xdp.data;
> >                       }
> >
> >                       switch (act) {
> >                       case XDP_PASS:
> >                               break;
> >                       case XDP_REDIRECT:
> > -                             if (likely(!xdp_do_redirect(dev, &xdp, xdp_prog))) {
> > +                             if (likely(!xdp_do_redirect(dev, &mxbuf.xdp, xdp_prog))) {
> >                                       ring->xdp_redirect++;
> >                                       xdp_redir_flush = true;
> >                                       frags[0].page = NULL;