Re: [PATCH -next] compiler.h: fix compile error with gcc-8 or lower version

[Vlastimil Babka]

On 9/29/22 05:38, Yang Yingliang wrote:
> I got the follow compile error in latest linux-next kernel with gcc-8.4:
> 
>   In file included from <command-line>:
>   ./include/linux/percpu.h: In function ‘__alloc_reserved_percpu’:
>   ././include/linux/compiler_types.h:279:30: error: expected declaration specifiers before ‘__alloc_size__’
>    #define __alloc_size(x, ...) __alloc_size__(x, ## __VA_ARGS__) __malloc
>                                 ^~~~~~~~~~~~~~
>   ./include/linux/percpu.h:120:74: note: in expansion of macro ‘__alloc_size’
>    extern void __percpu *__alloc_reserved_percpu(size_t size, size_t align) __alloc_size(1);
> 
> __alloc_size is not defined in gcc-8 or lower version, so add back the
> conditional test for __alloc_size__ to fix it.
> 
> Fixes: 63caa04ec605 ("slab: Remove __malloc attribute from realloc functions")
> Signed-off-by: Yang Yingliang <yangyingliang@xxxxxxxxxx>
> ---
>  include/linux/compiler_types.h | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/include/linux/compiler_types.h b/include/linux/compiler_types.h
> index aa81da7a28eb..aae8852ccbdc 100644
> --- a/include/linux/compiler_types.h
> +++ b/include/linux/compiler_types.h
> @@ -276,8 +276,13 @@ struct ftrace_likely_data {
>   * be performing a _reallocation_, as that may alias the existing pointer.
>   * For these, use __realloc_size().
>   */
> +#ifdef __alloc_size__
>  #define __alloc_size(x, ...)	__alloc_size__(x, ## __VA_ARGS__) __malloc
> -#define __realloc_size(x, ...)	__alloc_size__(x, ## __VA_ARGS__)
> +#define __realloc_size(x, ...) __alloc_size__(x, ## __VA_ARGS__)
> +#else
> +#define __alloc_size(x, ...)	__malloc
> +#define __realloc_size(x, ...) __malloc

This would be wrong as with 63caa04ec605 we don't want __malloc in
__realloc_size(). Anyway Kees sent the correct version and it's now merged,
thanks.

> +#endif
>  
>  #ifndef asm_volatile_goto
>  #define asm_volatile_goto(x...) asm goto(x)