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Commit 7cae7e26 authored by James Morris's avatar James Morris Committed by Linus Torvalds
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[PATCH] SELinux: add slab cache for inode security struct 



Add a slab cache for the SELinux inode security struct, one of which is
allocated for every inode instantiated by the system.

The memory savings are considerable.

On 64-bit, instead of the size-128 cache, we have a slab object of 96
bytes, saving 32 bytes per object.  After booting, I see about 4000 of
these and then about 17,000 after a kernel compile.  With this patch, we
save around 530KB of kernel memory in the latter case.  On 32-bit, the
savings are about half of this.

Signed-off-by: default avatarJames Morris <jmorris@namei.org>
Acked-by: default avatarStephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent cf01efd0

security/selinux/hooks.c

+8 −2
Original line number Diff line number Diff line
@@ -117,6 +117,8 @@ static struct security_operations *secondary_ops = NULL; 
static LIST_HEAD(superblock_security_head);

static DEFINE_SPINLOCK(sb_security_lock);



static kmem_cache_t *sel_inode_cache;



/* Allocate and free functions for each kind of security blob. */



static int task_alloc_security(struct task_struct *task)
@@ -146,10 +148,11 @@ static int inode_alloc_security(struct inode *inode) 
	struct task_security_struct *tsec = current->security;

	struct inode_security_struct *isec;



	isec = kzalloc(sizeof(struct inode_security_struct), GFP_KERNEL);

	isec = kmem_cache_alloc(sel_inode_cache, SLAB_KERNEL);

	if (!isec)

		return -ENOMEM;



	memset(isec, 0, sizeof(*isec));

	init_MUTEX(&isec->sem);

	INIT_LIST_HEAD(&isec->list);

	isec->inode = inode;
@@ -172,7 +175,7 @@ static void inode_free_security(struct inode *inode) 
	spin_unlock(&sbsec->isec_lock);



	inode->i_security = NULL;

	kfree(isec);

	kmem_cache_free(sel_inode_cache, isec);

}



static int file_alloc_security(struct file *file)
@@ -4406,6 +4409,9 @@ static __init int selinux_init(void) 
	tsec = current->security;

	tsec->osid = tsec->sid = SECINITSID_KERNEL;



	sel_inode_cache = kmem_cache_create("selinux_inode_security",

					    sizeof(struct inode_security_struct),

					    0, SLAB_PANIC, NULL, NULL);

	avc_init();



	original_ops = secondary_ops = security_ops;