Re: [PATCH] mm/slub: quiet the clang warning with -Wunused-function enabled

[Matthew Wilcox <willy@infradead.org>]

On Wed, Jul 10, 2024 at 10:54:18AM +0800, sxwjean@me.com wrote:
> From: Xiongwei Song <xiongwei.song@linux.dev>
> 
> The only user of prepare_slab_obj_exts_hook() is
> alloc_tagging_slab_alloc_hook(), which can build with
> CONFIG_MEM_ALLOC_PROFILING enabled. So, the warning was triggerred
> when disabling CONFIG_MEM_ALLOC_PROFILING. Let's add "__maybe_unused"
> for prepare_slab_obj_exts_hook().

Perhaps instead clang can be fixed to match gcc's behaviour?

> Reported-by: kernel test robot <lkp@intel.com>
> Closes: https://lore.kernel.org/oe-kbuild-all/202407050845.zNONqauD-lkp@intel.com/
> Signed-off-by: Xiongwei Song <xiongwei.song@linux.dev>
> ---
>  mm/slub.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/mm/slub.c b/mm/slub.c
> index ce39544acf7c..2e26f20759c0 100644
> --- a/mm/slub.c
> +++ b/mm/slub.c
> @@ -2027,7 +2027,7 @@ static inline bool need_slab_obj_ext(void)
>  	return false;
>  }
>  
> -static inline struct slabobj_ext *
> +static inline struct slabobj_ext * __maybe_unused
>  prepare_slab_obj_exts_hook(struct kmem_cache *s, gfp_t flags, void *p)
>  {
>  	struct slab *slab;
> @@ -2068,7 +2068,7 @@ static inline bool need_slab_obj_ext(void)
>  	return false;
>  }
>  
> -static inline struct slabobj_ext *
> +static inline struct slabobj_ext * __maybe_unused
>  prepare_slab_obj_exts_hook(struct kmem_cache *s, gfp_t flags, void *p)
>  {
>  	return NULL;
> -- 
> 2.34.1
> 
>