[PATCH] selinux: Use kmem_cache for hashtab_node

[Kyeongdon Kim]

During random test as own device to check slub account,
we found some slack memory from hashtab_node(kmalloc-64).
By using kzalloc(), middle of test result like below:
allocated size 240768
request size 45144
slack size 195624
allocation count 3762

So, we want to use kmem_cache_zalloc() and that
can reduce memory size 52byte(slack size/alloc count) per each struct.

Signed-off-by: Kyeongdon Kim <kyeongdon....@lge.com>
---
 security/selinux/ss/hashtab.c  | 17 +++++++++++++++--
 security/selinux/ss/hashtab.h  |  4 ++++
 security/selinux/ss/services.c |  4 ++++
 3 files changed, 23 insertions(+), 2 deletions(-)

diff --git a/security/selinux/ss/hashtab.c b/security/selinux/ss/hashtab.c
index 686c391..bef7577 100644
--- a/security/selinux/ss/hashtab.c
+++ b/security/selinux/ss/hashtab.c
@@ -9,6 +9,8 @@
 #include <linux/sched.h>
 #include "hashtab.h"
 
+static struct kmem_cache *hashtab_node_cachep;
+
 struct hashtab *hashtab_create(u32 (*hash_value)(struct hashtab *h, const void 
*key),
                               int (*keycmp)(struct hashtab *h, const void 
*key1, const void *key2),
                               u32 size)
@@ -57,7 +59,7 @@ int hashtab_insert(struct hashtab *h, void *key, void *datum)
        if (cur && (h->keycmp(h, key, cur->key) == 0))
                return -EEXIST;
 
-       newnode = kzalloc(sizeof(*newnode), GFP_KERNEL);
+       newnode = kmem_cache_zalloc(hashtab_node_cachep, GFP_KERNEL);
        if (!newnode)
                return -ENOMEM;
        newnode->key = key;
@@ -106,7 +108,7 @@ void hashtab_destroy(struct hashtab *h)
                while (cur) {
                        temp = cur;
                        cur = cur->next;
-                       kfree(temp);
+                       kmem_cache_free(hashtab_node_cachep, temp);
                }
                h->htable[i] = NULL;
        }
@@ -166,3 +168,14 @@ void hashtab_stat(struct hashtab *h, struct hashtab_info 
*info)
        info->slots_used = slots_used;
        info->max_chain_len = max_chain_len;
 }
+void hashtab_cache_init(void)
+{
+               hashtab_node_cachep = kmem_cache_create("hashtab_node",
+                       sizeof(struct hashtab_node),
+                       0, SLAB_PANIC, NULL);
+}
+
+void hashtab_cache_destroy(void)
+{
+               kmem_cache_destroy(hashtab_node_cachep);
+}
diff --git a/security/selinux/ss/hashtab.h b/security/selinux/ss/hashtab.h
index 009fb5e..d6883d3 100644
--- a/security/selinux/ss/hashtab.h
+++ b/security/selinux/ss/hashtab.h
@@ -84,4 +84,8 @@ int hashtab_map(struct hashtab *h,
 /* Fill info with some hash table statistics */
 void hashtab_stat(struct hashtab *h, struct hashtab_info *info);
 
+/* Use kmem_cache for hashtab_node */
+void hashtab_cache_init(void);
+void hashtab_cache_destroy(void);
+
 #endif /* _SS_HASHTAB_H */
diff --git a/security/selinux/ss/services.c b/security/selinux/ss/services.c
index e4a1c0d..33cfe5d 100644
--- a/security/selinux/ss/services.c
+++ b/security/selinux/ss/services.c
@@ -2060,10 +2060,12 @@ int security_load_policy(void *data, size_t len)
        if (!ss_initialized) {
                avtab_cache_init();
                ebitmap_cache_init();
+               hashtab_cache_init();
                rc = policydb_read(&policydb, fp);
                if (rc) {
                        avtab_cache_destroy();
                        ebitmap_cache_destroy();
+                       hashtab_cache_destroy();
                        goto out;
                }
 
@@ -2075,6 +2077,7 @@ int security_load_policy(void *data, size_t len)
                        policydb_destroy(&policydb);
                        avtab_cache_destroy();
                        ebitmap_cache_destroy();
+                       hashtab_cache_destroy();
                        goto out;
                }
 
@@ -2083,6 +2086,7 @@ int security_load_policy(void *data, size_t len)
                        policydb_destroy(&policydb);
                        avtab_cache_destroy();
                        ebitmap_cache_destroy();
+                       hashtab_cache_destroy();
                        goto out;
                }
 
-- 
2.6.2