mm/slab: move and refactor __kmem_cache_alias()

Move __kmem_cache_alias() to slab_common.c since it's called by
__kmem_cache_create_args() and calls find_mergeable() that both
are in this file. We can remove two slab.h declarations and make
them static. Instead declare sysfs_slab_alias() from slub.c so
that __kmem_cache_alias() can keep calling it.

Add args parameter to __kmem_cache_alias() and find_mergeable() instead
of align and ctor. With that we can also move the checks for usersize
and sheaf_capacity there from __kmem_cache_create_args() and make the
result more symmetric with slab_unmergeable().

No functional changes intended.

Reviewed-by: Harry Yoo <harry.yoo@oracle.com>
Reviewed-by: Suren Baghdasaryan <surenb@google.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>

Author: tehcaster

mm/slab.h

@@ -281,9 +281,12 @@ struct kmem_cache {
 #define SLAB_SUPPORTS_SYSFS 1
 void sysfs_slab_unlink(struct kmem_cache *s);
 void sysfs_slab_release(struct kmem_cache *s);
+int sysfs_slab_alias(struct kmem_cache *s, const char *name);
 #else
 static inline void sysfs_slab_unlink(struct kmem_cache *s) { }
 static inline void sysfs_slab_release(struct kmem_cache *s) { }
+static inline int sysfs_slab_alias(struct kmem_cache *s, const char *name)
+							{ return 0; }
 #endif
 
 void *fixup_red_left(struct kmem_cache *s, void *p);
@@ -400,11 +403,6 @@ extern void create_boot_cache(struct kmem_cache *, const char *name,
 			unsigned int useroffset, unsigned int usersize);
 
 int slab_unmergeable(struct kmem_cache *s);
-struct kmem_cache *find_mergeable(unsigned size, unsigned align,
-		slab_flags_t flags, const char *name, void (*ctor)(void *));
-struct kmem_cache *
-__kmem_cache_alias(const char *name, unsigned int size, unsigned int align,
-		   slab_flags_t flags, void (*ctor)(void *));
 
 slab_flags_t kmem_cache_flags(slab_flags_t flags, const char *name);
 

mm/slab_common.c

@@ -174,15 +174,22 @@ int slab_unmergeable(struct kmem_cache *s)
 	return 0;
 }
 
-struct kmem_cache *find_mergeable(unsigned int size, unsigned int align,
-		slab_flags_t flags, const char *name, void (*ctor)(void *))
+static struct kmem_cache *find_mergeable(unsigned int size, slab_flags_t flags,
+		const char *name, struct kmem_cache_args *args)
 {
 	struct kmem_cache *s;
+	unsigned int align;
 
 	if (slab_nomerge)
 		return NULL;
 
-	if (ctor)
+	if (args->ctor)
+		return NULL;
+
+	if (IS_ENABLED(CONFIG_HARDENED_USERCOPY) && args->usersize)
+		return NULL;
+
+	if (args->sheaf_capacity)
 		return NULL;
 
 	flags = kmem_cache_flags(flags, name);
@@ -191,7 +198,7 @@ struct kmem_cache *find_mergeable(unsigned int size, unsigned int align,
 		return NULL;
 
 	size = ALIGN(size, sizeof(void *));
-	align = calculate_alignment(flags, align, size);
+	align = calculate_alignment(flags, args->align, size);
 	size = ALIGN(size, align);
 
 	list_for_each_entry_reverse(s, &slab_caches, list) {
@@ -252,6 +259,31 @@ static struct kmem_cache *create_cache(const char *name,
 	return ERR_PTR(err);
 }
 
+static struct kmem_cache *
+__kmem_cache_alias(const char *name, unsigned int size, slab_flags_t flags,
+		   struct kmem_cache_args *args)
+{
+	struct kmem_cache *s;
+
+	s = find_mergeable(size, flags, name, args);
+	if (s) {
+		if (sysfs_slab_alias(s, name))
+			pr_err("SLUB: Unable to add cache alias %s to sysfs\n",
+			       name);
+
+		s->refcount++;
+
+		/*
+		 * Adjust the object sizes so that we clear
+		 * the complete object on kzalloc.
+		 */
+		s->object_size = max(s->object_size, size);
+		s->inuse = max(s->inuse, ALIGN(size, sizeof(void *)));
+	}
+
+	return s;
+}
+
 /**
  * __kmem_cache_create_args - Create a kmem cache.
  * @name: A string which is used in /proc/slabinfo to identify this cache.
@@ -323,9 +355,7 @@ struct kmem_cache *__kmem_cache_create_args(const char *name,
 		    object_size - args->usersize < args->useroffset))
 		args->usersize = args->useroffset = 0;
 
-	if (!args->usersize && !args->sheaf_capacity)
-		s = __kmem_cache_alias(name, object_size, args->align, flags,
-				       args->ctor);
+	s = __kmem_cache_alias(name, object_size, flags, args);
 	if (s)
 		goto out_unlock;
 

mm/slub.c

@@ -350,11 +350,8 @@ enum track_item { TRACK_ALLOC, TRACK_FREE };
 
 #ifdef SLAB_SUPPORTS_SYSFS
 static int sysfs_slab_add(struct kmem_cache *);
-static int sysfs_slab_alias(struct kmem_cache *, const char *);
 #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; }
 #endif
 
 #if defined(CONFIG_DEBUG_FS) && defined(CONFIG_SLUB_DEBUG)
@@ -8580,31 +8577,6 @@ void __init kmem_cache_init_late(void)
 	WARN_ON(!flushwq);
 }
 
-struct kmem_cache *
-__kmem_cache_alias(const char *name, unsigned int size, unsigned int align,
-		   slab_flags_t flags, void (*ctor)(void *))
-{
-	struct kmem_cache *s;
-
-	s = find_mergeable(size, align, flags, name, ctor);
-	if (s) {
-		if (sysfs_slab_alias(s, name))
-			pr_err("SLUB: Unable to add cache alias %s to sysfs\n",
-			       name);
-
-		s->refcount++;
-
-		/*
-		 * Adjust the object sizes so that we clear
-		 * the complete object on kzalloc.
-		 */
-		s->object_size = max(s->object_size, size);
-		s->inuse = max(s->inuse, ALIGN(size, sizeof(void *)));
-	}
-
-	return s;
-}
-
 int do_kmem_cache_create(struct kmem_cache *s, const char *name,
 			 unsigned int size, struct kmem_cache_args *args,
 			 slab_flags_t flags)
@@ -9837,7 +9809,7 @@ struct saved_alias {
 
 static struct saved_alias *alias_list;
 
-static int sysfs_slab_alias(struct kmem_cache *s, const char *name)
+int sysfs_slab_alias(struct kmem_cache *s, const char *name)
 {
 	struct saved_alias *al;