Re: [PATCH 14/18] netmem: use _Generic to cover const casting for page_to_netmem()

Mina Almasry
2025-05-23T17:15:07Z

On Thu, May 22, 2025 at 8:26 PM Byungchul Park <byungchul@sk.com> wrote:
>
> The current page_to_netmem() doesn't cover const casting resulting in
> trying to cast const struct page * to const netmem_ref fails.
>
> To cover the case, change page_to_netmem() to use macro and _Generic.
>
> Signed-off-by: Byungchul Park <byungchul@sk.com>

Reviewed-by: Mina Almasry <almasrymina@google.com>

> ---
> include/net/netmem.h | 7 +++----
> 1 file changed, 3 insertions(+), 4 deletions(-)
>
> diff --git a/include/net/netmem.h b/include/net/netmem.h
> index 29c005d70c4f..c2eb121181c2 100644
> --- a/include/net/netmem.h
> +++ b/include/net/netmem.h
> @@ -172,10 +172,9 @@ static inline netmem_ref net_iov_to_netmem(struct net_iov *niov)
> return (__force netmem_ref)((unsigned long)niov | NET_IOV);
> }
>
> -static inline netmem_ref page_to_netmem(struct page *page)
> -{
> - return (__force netmem_ref)page;
> -}
> +#define page_to_netmem(p) (_Generic((p), \
> + const struct page *: (__force const netmem_ref)(p), \
> + struct page *: (__force netmem_ref)(p)))
>
> static inline netmem_ref alloc_netmems_node(int nid, gfp_t gfp_mask,
> unsigned int order)
> --
> 2.17.1
>

--
Thanks,
Mina