netmem: use _Generic to cover const casting for page_to_netmem()

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>
Reviewed-by: Toke Høiland-Jørgensen <toke@redhat.com>
Reviewed-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://patch.msgid.link/20250702053256.4594-5-byungchul@sk.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/include/net/netmem.h b/include/net/netmem.h
index 7a1dafa3f0801a43542ad3ab795b6c96ff6c5228..de1d95f04076cdea8e8e3715dc9dfc9152bf5863 100644 (file)
--- a/include/net/netmem.h
+++ b/include/net/netmem.h
@@ -139,10 +139,9 @@ 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(const 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)))
 
 /**
  * virt_to_netmem - convert virtual memory pointer to a netmem reference