Re: [RFC PATCH net-next v5 08/14] memory-provider: dmabuf devmem memory provider

Pavel Begunkov
2024-02-13T13:29:26Z

On 12/18/23 02:40, Mina Almasry wrote:
> Implement a memory provider that allocates dmabuf devmem in the form of
> net_iov.
>
> The provider receives a reference to the struct netdev_dmabuf_binding
> via the pool->mp_priv pointer. The driver needs to set this pointer for
> the provider in the net_iov.
>
> The provider obtains a reference on the netdev_dmabuf_binding which
> guarantees the binding and the underlying mapping remains alive until
> the provider is destroyed.
>
> Usage of PP_FLAG_DMA_MAP is required for this memory provide such that
> the page_pool can provide the driver with the dma-addrs of the devmem.
>
> Support for PP_FLAG_DMA_SYNC_DEV is omitted for simplicity & p.order !=
> 0.
>
> Signed-off-by: Willem de Bruijn <willemb@google.com>
> Signed-off-by: Kaiyuan Zhang <kaiyuanz@google.com>
> Signed-off-by: Mina Almasry <almasrymina@google.com>
>
> ---
...
> +
> +static bool mp_dmabuf_devmem_release_page(struct page_pool *pool,
> + struct netmem *netmem)
> +{
> + WARN_ON_ONCE(!netmem_is_net_iov(netmem));
> +
> + page_pool_clear_pp_info(netmem);
> +
> + netdev_free_dmabuf(netmem_to_net_iov(netmem));
> +
> + /* We don't want the page pool put_page()ing our net_iovs. */
> + return false;
> +}
> +
> +const struct memory_provider_ops dmabuf_devmem_ops = {
> + .init = mp_dmabuf_devmem_init,
> + .destroy = mp_dmabuf_devmem_destroy,
> + .alloc_pages = mp_dmabuf_devmem_alloc_pages,
> + .release_page = mp_dmabuf_devmem_release_page,
> +};
> +EXPORT_SYMBOL(dmabuf_devmem_ops);

It might make sense to move all these functions together with
new code from core/dev.c into a new file

--
Pavel Begunkov