[PATCH] security: selinux: use kmem_cache for ebitmap

[Junil Lee]

The allocated size for each ebitmap_node is 192byte by kzalloc().
Then, ebitmap_node size is fixed, so it's possible to use only 144byte
for each object by kmem_cache_zalloc().
It can reduce some dynamic allocation size.

Signed-off-by: Junil Lee <junil0814.lee@xxxxxxx>
---
 security/selinux/ss/ebitmap.c  | 26 ++++++++++++++++++++------
 security/selinux/ss/ebitmap.h  |  3 +++
 security/selinux/ss/services.c |  4 ++++
 3 files changed, 27 insertions(+), 6 deletions(-)

diff --git a/security/selinux/ss/ebitmap.c b/security/selinux/ss/ebitmap.c
index 9db4709a..ad38299 100644
--- a/security/selinux/ss/ebitmap.c
+++ b/security/selinux/ss/ebitmap.c
@@ -24,6 +24,8 @@
 
 #define BITS_PER_U64	(sizeof(u64) * 8)
 
+static struct kmem_cache *ebitmap_node_cachep;
+
 int ebitmap_cmp(struct ebitmap *e1, struct ebitmap *e2)
 {
 	struct ebitmap_node *n1, *n2;
@@ -54,7 +56,7 @@ int ebitmap_cpy(struct ebitmap *dst, struct ebitmap *src)
 	n = src->node;
 	prev = NULL;
 	while (n) {
-		new = kzalloc(sizeof(*new), GFP_ATOMIC);
+		new = kmem_cache_zalloc(ebitmap_node_cachep, GFP_ATOMIC);
 		if (!new) {
 			ebitmap_destroy(dst);
 			return -ENOMEM;
@@ -162,7 +164,7 @@ int ebitmap_netlbl_import(struct ebitmap *ebmap,
 		if (e_iter == NULL ||
 		    offset >= e_iter->startbit + EBITMAP_SIZE) {
 			e_prev = e_iter;
-			e_iter = kzalloc(sizeof(*e_iter), GFP_ATOMIC);
+			e_iter = kmem_cache_zalloc(ebitmap_node_cachep, GFP_ATOMIC);
 			if (e_iter == NULL)
 				goto netlbl_import_failure;
 			e_iter->startbit = offset - (offset % EBITMAP_SIZE);
@@ -288,7 +290,7 @@ int ebitmap_set_bit(struct ebitmap *e, unsigned long bit, int value)
 					prev->next = n->next;
 				else
 					e->node = n->next;
-				kfree(n);
+				kmem_cache_free(ebitmap_node_cachep, n);
 			}
 			return 0;
 		}
@@ -299,7 +301,7 @@ int ebitmap_set_bit(struct ebitmap *e, unsigned long bit, int value)
 	if (!value)
 		return 0;
 
-	new = kzalloc(sizeof(*new), GFP_ATOMIC);
+	new = kmem_cache_zalloc(ebitmap_node_cachep, GFP_ATOMIC);
 	if (!new)
 		return -ENOMEM;
 
@@ -332,7 +334,7 @@ void ebitmap_destroy(struct ebitmap *e)
 	while (n) {
 		temp = n;
 		n = n->next;
-		kfree(temp);
+		kmem_cache_free(ebitmap_node_cachep, temp);
 	}
 
 	e->highbit = 0;
@@ -400,7 +402,7 @@ int ebitmap_read(struct ebitmap *e, void *fp)
 
 		if (!n || startbit >= n->startbit + EBITMAP_SIZE) {
 			struct ebitmap_node *tmp;
-			tmp = kzalloc(sizeof(*tmp), GFP_KERNEL);
+			tmp = kmem_cache_zalloc(ebitmap_node_cachep, GFP_KERNEL);
 			if (!tmp) {
 				printk(KERN_ERR
 				       "SELinux: ebitmap: out of memory\n");
@@ -519,3 +521,15 @@ int ebitmap_write(struct ebitmap *e, void *fp)
 	}
 	return 0;
 }
+
+void ebitmap_cache_init(void)
+{
+	ebitmap_node_cachep = kmem_cache_create("ebitmap_node",
+							sizeof(struct ebitmap_node),
+							0, SLAB_PANIC, NULL);
+}
+
+void ebitmap_cache_destroy(void)
+{
+	kmem_cache_destroy(ebitmap_node_cachep);
+}
diff --git a/security/selinux/ss/ebitmap.h b/security/selinux/ss/ebitmap.h
index 9637b8c..6d5a9ac 100644
--- a/security/selinux/ss/ebitmap.h
+++ b/security/selinux/ss/ebitmap.h
@@ -130,6 +130,9 @@ void ebitmap_destroy(struct ebitmap *e);
 int ebitmap_read(struct ebitmap *e, void *fp);
 int ebitmap_write(struct ebitmap *e, void *fp);
 
+void ebitmap_cache_init(void);
+void ebitmap_cache_destroy(void);
+
 #ifdef CONFIG_NETLABEL
 int ebitmap_netlbl_export(struct ebitmap *ebmap,
 			  struct netlbl_lsm_catmap **catmap);
diff --git a/security/selinux/ss/services.c b/security/selinux/ss/services.c
index 2021666..2f02fa6 100644
--- a/security/selinux/ss/services.c
+++ b/security/selinux/ss/services.c
@@ -2054,9 +2054,11 @@ int security_load_policy(void *data, size_t len)
 
 	if (!ss_initialized) {
 		avtab_cache_init();
+		ebitmap_cache_init();
 		rc = policydb_read(&policydb, fp);
 		if (rc) {
 			avtab_cache_destroy();
+			ebitmap_cache_destroy();
 			goto out;
 		}
 
@@ -2067,6 +2069,7 @@ int security_load_policy(void *data, size_t len)
 		if (rc) {
 			policydb_destroy(&policydb);
 			avtab_cache_destroy();
+			ebitmap_cache_destroy();
 			goto out;
 		}
 
@@ -2074,6 +2077,7 @@ int security_load_policy(void *data, size_t len)
 		if (rc) {
 			policydb_destroy(&policydb);
 			avtab_cache_destroy();
+			ebitmap_cache_destroy();
 			goto out;
 		}
 
-- 
2.6.2