mm/sl[aou]b: Move duping of slab name to slab_common.c

Duping of the slabname has to be done by each slab. Moving this code to
slab_common avoids duplicate implementations.

With this patch we have common string handling for all slab allocators.
Strings passed to kmem_cache_create() are copied internally. Subsystems
can create temporary strings to create slab caches.

Slabs allocated in early states of bootstrap will never be freed (and
those can never be freed since they are essential to slab allocator
operations).  During bootstrap we therefore do not have to worry about
duping names.

Reviewed-by: Glauber Costa <glommer@parallels.com>
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>

mm/slab_common.c

@@ -100,6 +100,7 @@ struct kmem_cache *kmem_cache_create(const char *name, size_t size, size_t align
 {
 	struct kmem_cache *s = NULL;
 	int err = 0;
+	char *n;
 
 	get_online_cpus();
 	mutex_lock(&slab_mutex);
@@ -108,16 +109,26 @@ struct kmem_cache *kmem_cache_create(const char *name, size_t size, size_t align
 		goto out_locked;
 
 
-	s = __kmem_cache_create(name, size, align, flags, ctor);
-	if (!s)
-		err = -ENOSYS; /* Until __kmem_cache_create returns code */
+	n = kstrdup(name, GFP_KERNEL);
+	if (!n) {
+		err = -ENOMEM;
+		goto out_locked;
+	}
+
+	s = __kmem_cache_create(n, size, align, flags, ctor);
+
+	if (s) {
+		/*
+		 * Check if the slab has actually been created and if it was a
+		 * real instatiation. Aliases do not belong on the list
+		 */
+		if (s->refcount == 1)
+			list_add(&s->list, &slab_caches);
 
-	/*
-	 * Check if the slab has actually been created and if it was a
-	 * real instatiation. Aliases do not belong on the list
-	 */
-	if (s && s->refcount == 1)
-		list_add(&s->list, &slab_caches);
+	} else {
+		kfree(n);
+		err = -ENOSYS; /* Until __kmem_cache_create returns code */
+	}
 
 out_locked:
 	mutex_unlock(&slab_mutex);
@@ -153,6 +164,7 @@ void kmem_cache_destroy(struct kmem_cache *s)
 			if (s->flags & SLAB_DESTROY_BY_RCU)
 				rcu_barrier();
 
+			kfree(s->name);
 			kmem_cache_free(kmem_cache, s);
 		} else {
 			list_add(&s->list, &slab_caches);

mm/slub.c

@@ -210,10 +210,7 @@ static void sysfs_slab_remove(struct kmem_cache *);
 static inline int sysfs_slab_add(struct kmem_cache *s) { return 0; }
 static inline int sysfs_slab_alias(struct kmem_cache *s, const char *p)
 							{ return 0; }
-static inline void sysfs_slab_remove(struct kmem_cache *s)
-{
-	kfree(s->name);
-}
+static inline void sysfs_slab_remove(struct kmem_cache *s) { }
 
 #endif
 
@@ -3929,7 +3926,6 @@ struct kmem_cache *__kmem_cache_create(const char *name, size_t size,
 		size_t align, unsigned long flags, void (*ctor)(void *))
 {
 	struct kmem_cache *s;
-	char *n;
 
 	s = find_mergeable(size, align, flags, name, ctor);
 	if (s) {
@@ -3948,13 +3944,9 @@ struct kmem_cache *__kmem_cache_create(const char *name, size_t size,
 		return s;
 	}
 
-	n = kstrdup(name, GFP_KERNEL);
-	if (!n)
-		return NULL;
-
 	s = kmem_cache_alloc(kmem_cache, GFP_KERNEL);
 	if (s) {
-		if (kmem_cache_open(s, n,
+		if (kmem_cache_open(s, name,
 				size, align, flags, ctor)) {
 			int r;
 
@@ -3969,7 +3961,6 @@ struct kmem_cache *__kmem_cache_create(const char *name, size_t size,
 		}
 		kmem_cache_free(kmem_cache, s);
 	}
-	kfree(n);
 	return NULL;
 }
 
@@ -5200,13 +5191,6 @@ static ssize_t slab_attr_store(struct kobject *kobj,
 	return err;
 }
 
-static void kmem_cache_release(struct kobject *kobj)
-{
-	struct kmem_cache *s = to_slab(kobj);
-
-	kfree(s->name);
-}
-
 static const struct sysfs_ops slab_sysfs_ops = {
 	.show = slab_attr_show,
 	.store = slab_attr_store,
@@ -5214,7 +5198,6 @@ static const struct sysfs_ops slab_sysfs_ops = {
 
 static struct kobj_type slab_ktype = {
 	.sysfs_ops = &slab_sysfs_ops,
-	.release = kmem_cache_release
 };
 
 static int uevent_filter(struct kset *kset, struct kobject *kobj)