Re: [PATCH net-next v9 6/8] mlx4: use netmem descriptor and APIs for page pool

[Mina Almasry <almasrymina@google.com>]

On Thu, Jul 10, 2025 at 1:28 AM Byungchul Park <byungchul@sk.com> wrote:
>
> To simplify struct page, the effort to separate its own descriptor from
> struct page is required and the work for page pool is on going.
>
> Use netmem descriptor and APIs for page pool in mlx4 code.
>
> Signed-off-by: Byungchul Park <byungchul@sk.com>
> ---
>  drivers/net/ethernet/mellanox/mlx4/en_rx.c   | 48 +++++++++++---------
>  drivers/net/ethernet/mellanox/mlx4/en_tx.c   |  8 ++--
>  drivers/net/ethernet/mellanox/mlx4/mlx4_en.h |  4 +-
>  3 files changed, 32 insertions(+), 28 deletions(-)
>
> diff --git a/drivers/net/ethernet/mellanox/mlx4/en_rx.c b/drivers/net/ethernet/mellanox/mlx4/en_rx.c
> index b33285d755b9..7cf0d2dc5011 100644
> --- a/drivers/net/ethernet/mellanox/mlx4/en_rx.c
> +++ b/drivers/net/ethernet/mellanox/mlx4/en_rx.c
> @@ -62,18 +62,18 @@ static int mlx4_en_alloc_frags(struct mlx4_en_priv *priv,
>         int i;
>
>         for (i = 0; i < priv->num_frags; i++, frags++) {
> -               if (!frags->page) {
> -                       frags->page = page_pool_alloc_pages(ring->pp, gfp);
> -                       if (!frags->page) {
> +               if (!frags->netmem) {
> +                       frags->netmem = page_pool_alloc_netmems(ring->pp, gfp);
> +                       if (!frags->netmem) {
>                                 ring->alloc_fail++;
>                                 return -ENOMEM;
>                         }
> -                       page_pool_fragment_page(frags->page, 1);
> +                       page_pool_fragment_netmem(frags->netmem, 1);
>                         frags->page_offset = priv->rx_headroom;
>
>                         ring->rx_alloc_pages++;
>                 }
> -               dma = page_pool_get_dma_addr(frags->page);
> +               dma = page_pool_get_dma_addr_netmem(frags->netmem);
>                 rx_desc->data[i].addr = cpu_to_be64(dma + frags->page_offset);
>         }
>         return 0;
> @@ -83,10 +83,10 @@ static void mlx4_en_free_frag(const struct mlx4_en_priv *priv,
>                               struct mlx4_en_rx_ring *ring,
>                               struct mlx4_en_rx_alloc *frag)
>  {
> -       if (frag->page)
> -               page_pool_put_full_page(ring->pp, frag->page, false);
> +       if (frag->netmem)
> +               page_pool_put_full_netmem(ring->pp, frag->netmem, false);
>         /* We need to clear all fields, otherwise a change of priv->log_rx_info
> -        * could lead to see garbage later in frag->page.
> +        * could lead to see garbage later in frag->netmem.
>          */
>         memset(frag, 0, sizeof(*frag));
>  }
> @@ -440,29 +440,33 @@ static int mlx4_en_complete_rx_desc(struct mlx4_en_priv *priv,
>         unsigned int truesize = 0;
>         bool release = true;
>         int nr, frag_size;
> -       struct page *page;
> +       netmem_ref netmem;
>         dma_addr_t dma;
>
>         /* Collect used fragments while replacing them in the HW descriptors */
>         for (nr = 0;; frags++) {
>                 frag_size = min_t(int, length, frag_info->frag_size);
>
> -               page = frags->page;
> -               if (unlikely(!page))
> +               netmem = frags->netmem;
> +               if (unlikely(!netmem))
>                         goto fail;
>
> -               dma = page_pool_get_dma_addr(page);
> +               dma = page_pool_get_dma_addr_netmem(netmem);
>                 dma_sync_single_range_for_cpu(priv->ddev, dma, frags->page_offset,
>                                               frag_size, priv->dma_dir);
>
> -               __skb_fill_page_desc(skb, nr, page, frags->page_offset,
> -                                    frag_size);
> +               __skb_fill_netmem_desc(skb, nr, netmem, frags->page_offset,
> +                                      frag_size);
>
>                 truesize += frag_info->frag_stride;
>                 if (frag_info->frag_stride == PAGE_SIZE / 2) {
> +                       struct page *page = netmem_to_page(netmem);

This cast is not safe, try to use the netmem type directly.

-- 
Thanks,
Mina