[RFC v3 12/18] netmem: use _Generic to cover const casting for page_to_netmem()

Byungchul Park
2025-05-29T03:11:10Z

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 d52f86082271..74f269c6815d 100644
--- a/include/net/netmem.h
+++ b/include/net/netmem.h
@@ -200,10 +200,9 @@ 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)))

/**
* virt_to_netmem - convert virtual memory pointer to a netmem reference
--
2.17.1