mm/sl[aou]b: Move sysfs_slab_add to common

Simplify locking by moving the slab_add_sysfs after all locks have been
dropped. Eases the upcoming move to provide sysfs support for all
allocators.
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.h

@@ -39,10 +39,13 @@ struct kmem_cache *__kmem_cache_create(const char *name, size_t size,
 #ifdef CONFIG_SLUB
 struct kmem_cache *__kmem_cache_alias(const char *name, size_t size,
 	size_t align, unsigned long flags, void (*ctor)(void *));
+extern int sysfs_slab_add(struct kmem_cache *s);
 #else
 static inline struct kmem_cache *__kmem_cache_alias(const char *name, size_t size,
 	size_t align, unsigned long flags, void (*ctor)(void *))
 { return NULL; }
+static inline int sysfs_slab_add(struct kmem_cache *s) { return 0; }
+
 #endif
 
 

mm/slab_common.c

@@ -152,6 +152,14 @@ struct kmem_cache *kmem_cache_create(const char *name, size_t size, size_t align
 		return NULL;
 	}
 
+	if (s->refcount == 1) {
+		err = sysfs_slab_add(s);
+		if (err)
+			printk(KERN_WARNING "kmem_cache_create(%s) failed to"
+				" create sysfs entry. Error %d\n",
+					name, err);
+	}
+
 	return s;
 }
 EXPORT_SYMBOL(kmem_cache_create);

mm/slub.c

@@ -202,12 +202,10 @@ struct track {
 enum track_item { TRACK_ALLOC, TRACK_FREE };
 
 #ifdef CONFIG_SYSFS
-static int sysfs_slab_add(struct kmem_cache *);
 static int sysfs_slab_alias(struct kmem_cache *, const char *);
 static void sysfs_slab_remove(struct kmem_cache *);
 
 #else
-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) { }
@@ -3955,16 +3953,7 @@ struct kmem_cache *__kmem_cache_create(const char *name, size_t size,
 	if (s) {
 		if (kmem_cache_open(s, name,
 				size, align, flags, ctor)) {
-			int r;
-
-			mutex_unlock(&slab_mutex);
-			r = sysfs_slab_add(s);
-			mutex_lock(&slab_mutex);
-
-			if (!r)
-				return s;
-
-			kmem_cache_close(s);
+			return s;
 		}
 		kmem_cache_free(kmem_cache, s);
 	}
@@ -5258,7 +5247,7 @@ static char *create_unique_id(struct kmem_cache *s)
 	return name;
 }
 
-static int sysfs_slab_add(struct kmem_cache *s)
+int sysfs_slab_add(struct kmem_cache *s)
 {
 	int err;
 	const char *name;