On 11/05, Mina Almasry wrote:
> Implement a memory provider that allocates dmabuf devmem page_pool_iovs.
>
> Support of PP_FLAG_DMA_MAP and PP_FLAG_DMA_SYNC_DEV is omitted for
> simplicity.
>
> 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 page_pool_params.
>
> 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.
>
> Signed-off-by: Willem de Bruijn <willemb@xxxxxxxxxx>
> Signed-off-by: Kaiyuan Zhang <kaiyuanz@xxxxxxxxxx>
> Signed-off-by: Mina Almasry <almasrymina@xxxxxxxxxx>
>
> ---
> include/net/page_pool/helpers.h | 40 +++++++++++++++++
> include/net/page_pool/types.h | 10 +++++
> net/core/page_pool.c | 76 +++++++++++++++++++++++++++++++++
> 3 files changed, 126 insertions(+)
>
> diff --git a/include/net/page_pool/helpers.h b/include/net/page_pool/helpers.h
> index 78cbb040af94..b93243c2a640 100644
> --- a/include/net/page_pool/helpers.h
> +++ b/include/net/page_pool/helpers.h
> @@ -53,6 +53,7 @@
> #define _NET_PAGE_POOL_HELPERS_H
>
> #include <net/page_pool/types.h>
> +#include <net/net_debug.h>
>
> #ifdef CONFIG_PAGE_POOL_STATS
> int page_pool_ethtool_stats_get_count(void);
> @@ -111,6 +112,45 @@ page_pool_iov_binding(const struct page_pool_iov *ppiov)
> return page_pool_iov_owner(ppiov)->binding;
> }
>
> +static inline int page_pool_iov_refcount(const struct page_pool_iov *ppiov)
> +{
> + return refcount_read(&ppiov->refcount);
> +}
> +
> +static inline void page_pool_iov_get_many(struct page_pool_iov *ppiov,
> + unsigned int count)
> +{
> + refcount_add(count, &ppiov->refcount);
> +}
> +
> +void __page_pool_iov_free(struct page_pool_iov *ppiov);
> +
> +static inline void page_pool_iov_put_many(struct page_pool_iov *ppiov,
> + unsigned int count)
> +{
> + if (!refcount_sub_and_test(count, &ppiov->refcount))
> + return;
> +
> + __page_pool_iov_free(ppiov);
> +}
> +
> +/* page pool mm helpers */
> +
> +static inline bool page_is_page_pool_iov(const struct page *page)
> +{
> + return (unsigned long)page & PP_DEVMEM;
> +}
Speaking of bpf: one thing that might be problematic with this PP_DEVMEM
bit is that it will make debugging with bpftrace a bit (more)
complicated. If somebody were trying to get to that page_pool_iov from
the frags, they will have to do the equivalent of page_is_page_pool_iov,
but probably not a big deal? (thinking out loud)
