Re: [net-next v1 08/16] memory-provider: dmabuf devmem memory provider

Yinjun Zhang
2023-12-13T07:49:22Z

On Thu, 7 Dec 2023 16:52:39 -0800, Mina Almasry wrote:
<...>
> +static int mp_dmabuf_devmem_init(struct page_pool *pool)
> +{
> + struct netdev_dmabuf_binding *binding = pool->mp_priv;
> +
> + if (!binding)
> + return -EINVAL;
> +
> + if (!(pool->p.flags & PP_FLAG_DMA_MAP))
> + return -EOPNOTSUPP;
> +
> + if (pool->p.flags & PP_FLAG_DMA_SYNC_DEV)
> + return -EOPNOTSUPP;
> +
> + netdev_dmabuf_binding_get(binding);
> + return 0;
> +}
> +
> +static struct page *mp_dmabuf_devmem_alloc_pages(struct page_pool *pool,
> + gfp_t gfp)
> +{
> + struct netdev_dmabuf_binding *binding = pool->mp_priv;
> + struct page_pool_iov *ppiov;
> +
> + ppiov = netdev_alloc_dmabuf(binding);

Since it only supports one-page allocation, we'd better add a check in
`ops->init()` that `pool->p.order` must be 0.

> + if (!ppiov)
> + return NULL;
> +
> + ppiov->pp = pool;
> + pool->pages_state_hold_cnt++;
> + trace_page_pool_state_hold(pool, (struct page *)ppiov,
> + pool->pages_state_hold_cnt);
> + return (struct page *)((unsigned long)ppiov | PP_IOV);
> +}
<...>