selinux: Use kmem_cache for hashtab_node

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.kim@lge.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>

3 files changed, 23 insertions, 2 deletions

diff --git a/security/selinux/ss/hashtab.c b/security/selinux/ss/hashtab.c
index 686c3917064c..bef7577d1270 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 009fb5e06172..d6883d3e7c5b 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 e4a1c0dc561a..33cfe5d3d6cb 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;
                 }