Re: [PATCH] mm: Make {,set}page_address() static inline ifWANT_PAGE_VIRTUAL

[Michael S. Tsirkin]

On Wed, Jan 15, 2014 at 10:33:46AM +0100, Geert Uytterhoeven wrote:
> {,set}page_address() are macros if WANT_PAGE_VIRTUAL.
> If !WANT_PAGE_VIRTUAL, they're plain C functions.
> 
> If someone calls them with a void *, this pointer is auto-converted to
> struct page * if !WANT_PAGE_VIRTUAL, but causes a build failure on
> architectures using WANT_PAGE_VIRTUAL (arc, m68k and sparc):
> 
> drivers/md/bcache/bset.c: In function â__btree_sortâ:
> drivers/md/bcache/bset.c:1190: warning: dereferencing âvoid *â pointer
> drivers/md/bcache/bset.c:1190: error: request for member âvirtualâ in something not a structure or union
> 
> Convert them to static inline functions to fix this. There are already
> plenty of  users of struct page members inside <linux/mm.h>, so there's no
> reason to keep them as macros.
> 
> Signed-off-by: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>

FWIW

Acked-by: Michael S. Tsirkin <mst@xxxxxxxxxx>

> ---
> http://kisskb.ellerman.id.au/kisskb/buildresult/10469287/ (m68k/next)
> http://kisskb.ellerman.id.au/kisskb/buildresult/10469488/ (sparc64/next)
> https://lkml.org/lkml/2014/1/13/1044 (m68k & sparc/3.10.27-stable)
> 
>  include/linux/mm.h |   13 ++++++++-----
>  1 file changed, 8 insertions(+), 5 deletions(-)
> 
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index 35527173cf50..9fac6dd69b11 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -846,11 +846,14 @@ static __always_inline void *lowmem_page_address(const struct page *page)
>  #endif
>  
>  #if defined(WANT_PAGE_VIRTUAL)
> -#define page_address(page) ((page)->virtual)
> -#define set_page_address(page, address)			\
> -	do {						\
> -		(page)->virtual = (address);		\
> -	} while(0)
> +static inline void *page_address(const struct page *page)
> +{
> +	return page->virtual;
> +}
> +static inline void set_page_address(struct page *page, void *address)
> +{
> +	page->virtual = address;
> +}
>  #define page_address_init()  do { } while(0)
>  #endif
>  
> -- 
> 1.7.9.5
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