linux-kernel - [PATCH v2] Security: smack: replace kzalloc with kmem_cache for inode

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Date:	Wed, 15 Oct 2014 17:40:41 +0530
From:	Rohit <rohit.kr@...sung.com>
To:	akpm@...ux-foundation.org, casey@...aufler-ca.com,
	james.l.morris@...cle.com, serge@...lyn.com,
	linux-security-module@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:	cpgs@...sung.com, pintu.k@...sung.com, rohit.kr@...sung.com,
	vishnu.ps@...sung.com, iqbal.ams@...sung.com,
	ed.savinay@...sung.com
Subject: [PATCH v2] Security: smack: replace kzalloc with kmem_cache for
 inode_smack

The patch use kmem_cache to allocate/free inode_smack since they are
alloced in high volumes making it a perfect case for kmem_cache.

As per analysis, 24 bytes of memory is wasted per allocation due
to internal fragmentation. With kmem_cache, this can be avoided.

Accounting of memory allocation is below :
 total       slack            net      count-alloc/free        caller
Before (with kzalloc)
1919872      719952          1919872      29998/0          new_inode_smack+0x14

After (with kmem_cache)
1201680          0           1201680      30042/0          new_inode_smack+0x18

>From above data, we found that 719952 bytes(~700 KB) of memory is
saved on allocation of 29998 smack inodes.

Signed-off-by: Rohit <rohit.kr@...sung.com>
---
Added static in kmem_cache object declaration noted by Andrew Morton <akpm@
linux-foundation.org> . Also updated commit message.
 security/smack/smack_lsm.c |   13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index d515ec2..15d985c 100644
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -53,6 +53,7 @@
 #define SMK_SENDING	2
 
 LIST_HEAD(smk_ipv6_port_list);
+static struct kmem_cache *smack_inode_cache;
 
 #ifdef CONFIG_SECURITY_SMACK_BRINGUP
 static void smk_bu_mode(int mode, char *s)
@@ -240,7 +241,7 @@ struct inode_smack *new_inode_smack(struct smack_known *skp)
 {
 	struct inode_smack *isp;
 
-	isp = kzalloc(sizeof(struct inode_smack), GFP_NOFS);
+	isp = kmem_cache_zalloc(smack_inode_cache, GFP_NOFS);
 	if (isp == NULL)
 		return NULL;
 
@@ -767,7 +768,7 @@ static int smack_inode_alloc_security(struct inode *inode)
  */
 static void smack_inode_free_security(struct inode *inode)
 {
-	kfree(inode->i_security);
+	kmem_cache_free(smack_inode_cache, inode->i_security);
 	inode->i_security = NULL;
 }
 
@@ -4264,10 +4265,16 @@ static __init int smack_init(void)
 	if (!security_module_enable(&smack_ops))
 		return 0;
 
+	smack_inode_cache = KMEM_CACHE(inode_smack, 0);
+	if (!smack_inode_cache)
+		return -ENOMEM;
+
 	tsp = new_task_smack(&smack_known_floor, &smack_known_floor,
 				GFP_KERNEL);
-	if (tsp == NULL)
+	if (tsp == NULL) {
+		kmem_cache_destroy(smack_inode_cache);
 		return -ENOMEM;
+	}
 
 	printk(KERN_INFO "Smack:  Initializing.\n");
 
-- 
1.7.9.5

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