From a10bf26b2f53242836e9362c6c9c857b627b82a9 Mon Sep 17 00:00:00 2001 From: Dmitry Kasatkin Date: Wed, 8 Feb 2012 14:15:42 -0500 Subject: [PATCH] ima: replace iint spinblock with rwlock/read_lock For performance, replace the iint spinlock with rwlock/read_lock. Eric Paris questioned this change, from spinlocks to rwlocks, saying "rwlocks have been shown to actually be slower on multi processor systems in a number of cases due to the cache line bouncing required." Based on performance measurements compiling the kernel on a cold boot with multiple jobs with/without this patch, Dmitry Kasatkin and I found that rwlocks performed better than spinlocks, but very insignificantly. For example with total compilation time around 6 minutes, with rwlocks time was 1 - 3 seconds shorter... but always like that. Changelog v2: - new patch taken from the 'allocating iint improvements' patch Signed-off-by: Dmitry Kasatkin Signed-off-by: Mimi Zohar --- security/integrity/iint.c | 16 +++++++--------- 1 file changed, 7 insertions(+), 9 deletions(-) diff --git a/security/integrity/iint.c b/security/integrity/iint.c index c91a436e13ac..d82a5a13d855 100644 --- a/security/integrity/iint.c +++ b/security/integrity/iint.c @@ -22,7 +22,7 @@ #include "integrity.h" static struct rb_root integrity_iint_tree = RB_ROOT; -static DEFINE_SPINLOCK(integrity_iint_lock); +static DEFINE_RWLOCK(integrity_iint_lock); static struct kmem_cache *iint_cache __read_mostly; int iint_initialized; @@ -35,8 +35,6 @@ static struct integrity_iint_cache *__integrity_iint_find(struct inode *inode) struct integrity_iint_cache *iint; struct rb_node *n = integrity_iint_tree.rb_node; - assert_spin_locked(&integrity_iint_lock); - while (n) { iint = rb_entry(n, struct integrity_iint_cache, rb_node); @@ -63,9 +61,9 @@ struct integrity_iint_cache *integrity_iint_find(struct inode *inode) if (!IS_IMA(inode)) return NULL; - spin_lock(&integrity_iint_lock); + read_lock(&integrity_iint_lock); iint = __integrity_iint_find(inode); - spin_unlock(&integrity_iint_lock); + read_unlock(&integrity_iint_lock); return iint; } @@ -100,7 +98,7 @@ struct integrity_iint_cache *integrity_inode_get(struct inode *inode) if (!iint) return NULL; - spin_lock(&integrity_iint_lock); + write_lock(&integrity_iint_lock); p = &integrity_iint_tree.rb_node; while (*p) { @@ -119,7 +117,7 @@ struct integrity_iint_cache *integrity_inode_get(struct inode *inode) rb_link_node(node, parent, p); rb_insert_color(node, &integrity_iint_tree); - spin_unlock(&integrity_iint_lock); + write_unlock(&integrity_iint_lock); return iint; } @@ -136,10 +134,10 @@ void integrity_inode_free(struct inode *inode) if (!IS_IMA(inode)) return; - spin_lock(&integrity_iint_lock); + write_lock(&integrity_iint_lock); iint = __integrity_iint_find(inode); rb_erase(&iint->rb_node, &integrity_iint_tree); - spin_unlock(&integrity_iint_lock); + write_unlock(&integrity_iint_lock); iint_free(iint); } -- 2.30.2