mm, slab: dissolve shutdown_cache() into its caller

There's only one caller of shutdown_cache() so move the code into it.
Preparatory patch for further changes, no functional change.
Reviewed-by: Jann Horn <jannh@google.com>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>

mm/slab_common.c

@@ -540,27 +540,6 @@ static void slab_caches_to_rcu_destroy_workfn(struct work_struct *work)
 	}
 }
 
-static int shutdown_cache(struct kmem_cache *s)
-{
-	/* free asan quarantined objects */
-	kasan_cache_shutdown(s);
-
-	if (__kmem_cache_shutdown(s) != 0)
-		return -EBUSY;
-
-	list_del(&s->list);
-
-	if (s->flags & SLAB_TYPESAFE_BY_RCU) {
-		list_add_tail(&s->list, &slab_caches_to_rcu_destroy);
-		schedule_work(&slab_caches_to_rcu_destroy_work);
-	} else {
-		kfence_shutdown_cache(s);
-		debugfs_slab_release(s);
-	}
-
-	return 0;
-}
-
 void slab_kmem_cache_release(struct kmem_cache *s)
 {
 	__kmem_cache_release(s);
@@ -585,9 +564,26 @@ void kmem_cache_destroy(struct kmem_cache *s)
 	if (s->refcount)
 		goto out_unlock;
 
-	err = shutdown_cache(s);
+	/* free asan quarantined objects */
+	kasan_cache_shutdown(s);
+
+	err = __kmem_cache_shutdown(s);
 	WARN(err, "%s %s: Slab cache still has objects when called from %pS",
 	     __func__, s->name, (void *)_RET_IP_);
+
+	if (err)
+		goto out_unlock;
+
+	list_del(&s->list);
+
+	if (rcu_set) {
+		list_add_tail(&s->list, &slab_caches_to_rcu_destroy);
+		schedule_work(&slab_caches_to_rcu_destroy_work);
+	} else {
+		kfence_shutdown_cache(s);
+		debugfs_slab_release(s);
+	}
+
 out_unlock:
 	mutex_unlock(&slab_mutex);
 	cpus_read_unlock();