Re: [PATCH v2 1/2] slab: Clean up SLOB vs kmalloc() definition

[Hyeonggon Yoo]

On Thu, Nov 17, 2022 at 07:51:58PM -0800, Kees Cook wrote:
> As already done for kmalloc_node(), clean up the #ifdef usage in the
> definition of kmalloc() so that the SLOB-only version is an entirely
> separate and much more readable function.
> 
> Cc: Vlastimil Babka <vbabka@xxxxxxx>
> Cc: Christoph Lameter <cl@xxxxxxxxx>
> Cc: Pekka Enberg <penberg@xxxxxxxxxx>
> Cc: David Rientjes <rientjes@xxxxxxxxxx>
> Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> Cc: Roman Gushchin <roman.gushchin@xxxxxxxxx>
> Cc: Hyeonggon Yoo <42.hyeyoo@xxxxxxxxx>
> Cc: linux-mm@xxxxxxxxx
> Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
> ---
>  include/linux/slab.h | 16 ++++++++++++----
>  1 file changed, 12 insertions(+), 4 deletions(-)
> 
> diff --git a/include/linux/slab.h b/include/linux/slab.h
> index 1c670c16c737..9033937c758e 100644
> --- a/include/linux/slab.h
> +++ b/include/linux/slab.h
> @@ -558,15 +558,15 @@ void *kmalloc_large_node(size_t size, gfp_t flags, int node) __assume_page_align
>   *	Try really hard to succeed the allocation but fail
>   *	eventually.
>   */
> +#ifndef CONFIG_SLOB
>  static __always_inline __alloc_size(1) void *kmalloc(size_t size, gfp_t flags)
>  {
>  	if (__builtin_constant_p(size)) {
> -#ifndef CONFIG_SLOB
>  		unsigned int index;
> -#endif
> +
>  		if (size > KMALLOC_MAX_CACHE_SIZE)
>  			return kmalloc_large(size, flags);
> -#ifndef CONFIG_SLOB
> +
>  		index = kmalloc_index(size);
>  
>  		if (!index)
> @@ -575,10 +575,18 @@ static __always_inline __alloc_size(1) void *kmalloc(size_t size, gfp_t flags)
>  		return kmalloc_trace(
>  				kmalloc_caches[kmalloc_type(flags)][index],
>  				flags, size);
> -#endif
>  	}
>  	return __kmalloc(size, flags);
>  }
> +#else
> +static __always_inline __alloc_size(1) void *kmalloc(size_t size, gfp_t flags)
> +{
> +	if (__builtin_constant_p(size) && size > KMALLOC_MAX_CACHE_SIZE)
> +		return kmalloc_large(size, flags);
> +
> +	return __kmalloc(size, flags);
> +}
> +#endif
>  
>  #ifndef CONFIG_SLOB
>  static __always_inline __alloc_size(1) void *kmalloc_node(size_t size, gfp_t flags, int node)
> -- 
> 2.34.1

Reviewed-by: Hyeonggon Yoo <42.hyeyoo@xxxxxxxxx>

-- 
Thanks,
Hyeonggon