kasan: introduce set_alloc_info

Add set_alloc_info() helper and move kasan_set_track() into it. This will
simplify the code for one of the upcoming changes.

No functional changes.

Link: https://lkml.kernel.org/r/b2393e8f1e311a70fc3aaa2196461b6acdee7d21.1606162397.git.andreyknvl@google.com
Link: https://linux-review.googlesource.com/id/I0316193cbb4ecc9b87b7c2eee0dd79f8ec908c1a
Signed-off-by: Andrey Konovalov <[email protected]>
Reviewed-by: Dmitry Vyukov <[email protected]>
Reviewed-by: Marco Elver <[email protected]>
Tested-by: Vincenzo Frascino <[email protected]>
Cc: Alexander Potapenko <[email protected]>
Cc: Andrey Ryabinin <[email protected]>
Cc: Branislav Rankov <[email protected]>
Cc: Catalin Marinas <[email protected]>
Cc: Evgenii Stepanov <[email protected]>
Cc: Kevin Brodsky <[email protected]>
Cc: Vasily Gorbik <[email protected]>
Cc: Will Deacon <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

mm/kasan/common.c

@@ -323,6 +323,11 @@ bool kasan_slab_free(struct kmem_cache *cache, void *object, unsigned long ip)
 	return __kasan_slab_free(cache, object, ip, true);
 }
 
+static void set_alloc_info(struct kmem_cache *cache, void *object, gfp_t flags)
+{
+	kasan_set_track(&kasan_get_alloc_meta(cache, object)->alloc_track, flags);
+}
+
 static void *__kasan_kmalloc(struct kmem_cache *cache, const void *object,
 				size_t size, gfp_t flags, bool keep_tag)
 {
@@ -350,7 +355,7 @@ static void *__kasan_kmalloc(struct kmem_cache *cache, const void *object,
 		     KASAN_KMALLOC_REDZONE);
 
 	if (cache->flags & SLAB_KASAN)
-		kasan_set_track(&kasan_get_alloc_meta(cache, object)->alloc_track, flags);
+		set_alloc_info(cache, (void *)object, flags);
 
 	return set_tag(object, tag);
 }