Re: [PATCH RFC v2 19/33] nfp: add XDP frame size to netronome driver

Jakub Kicinski
2020-04-08T17:53:48Z

On Wed, 08 Apr 2020 13:52:10 +0200 Jesper Dangaard Brouer wrote:
> The netronome nfp driver already had a true_bufsz variable
> that contains what was needed for xdp.frame_sz.
>
> Cc: Jakub Kicinski <kuba@kernel.org>
> Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
> ---
> .../net/ethernet/netronome/nfp/nfp_net_common.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/drivers/net/ethernet/netronome/nfp/nfp_net_common.c b/drivers/net/ethernet/netronome/nfp/nfp_net_common.c
> index 9bfb3b077bc1..b9b8c30eab33 100644
> --- a/drivers/net/ethernet/netronome/nfp/nfp_net_common.c
> +++ b/drivers/net/ethernet/netronome/nfp/nfp_net_common.c
> @@ -1817,6 +1817,7 @@ static int nfp_net_rx(struct nfp_net_rx_ring *rx_ring, int budget)
> rcu_read_lock();
> xdp_prog = READ_ONCE(dp->xdp_prog);
> true_bufsz = xdp_prog ? PAGE_SIZE : dp->fl_bufsz;
> + xdp.frame_sz = true_bufsz;

Since this matters only with XDP on - we can set to PAGE_SIZE directly?

But more importantly the correct value is:

PAGE_SIZE - NFP_NET_RX_BUF_HEADROOM

as we set hard_start at an offset.

xdp.data_hard_start = rxbuf->frag + NFP_NET_RX_BUF_HEADROOM;

Cause NFP_NET_RX_BUF_HEADROOM is not DMA mapped.

> xdp.rxq = &rx_ring->xdp_rxq;
> tx_ring = r_vec->xdp_ring;