mm/slab: Introduce kmem_buckets typedef

Encapsulate the concept of a single set of kmem_caches that are used
for the kmalloc size buckets. Redefine kmalloc_caches as an array
of these buckets (for the different global cache buckets).
Signed-off-by: Kees Cook <kees@kernel.org>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>

include/linux/slab.h

@@ -426,8 +426,9 @@ enum kmalloc_cache_type {
 	NR_KMALLOC_TYPES
 };
 
-extern struct kmem_cache *
-kmalloc_caches[NR_KMALLOC_TYPES][KMALLOC_SHIFT_HIGH + 1];
+typedef struct kmem_cache * kmem_buckets[KMALLOC_SHIFT_HIGH + 1];
+
+extern kmem_buckets kmalloc_caches[NR_KMALLOC_TYPES];
 
 /*
  * Define gfp bits that should not be set for KMALLOC_NORMAL.

mm/slab_common.c

@@ -654,8 +654,7 @@ static struct kmem_cache *__init create_kmalloc_cache(const char *name,
 	return s;
 }
 
-struct kmem_cache *
-kmalloc_caches[NR_KMALLOC_TYPES][KMALLOC_SHIFT_HIGH + 1] __ro_after_init =
+kmem_buckets kmalloc_caches[NR_KMALLOC_TYPES] __ro_after_init =
 { /* initialization for https://llvm.org/pr42570 */ };
 EXPORT_SYMBOL(kmalloc_caches);