From cc9cb219aac24ffc711566c8f372c2b3a3bf840f Mon Sep 17 00:00:00 2001 From: Pavel Emelyanov Date: Thu, 5 Jun 2008 22:46:26 -0700 Subject: [PATCH] devscgroup: relax task to dev_cgroup conversion Two functions, that need to get a device_cgroup from a task (they are devcgroup_inode_permission and devcgroup_inode_mknod) make it in a strange way: They get a css_set from task, then a subsys_state from css_set, then a cgroup from the state and then a subsys_state again from the cgroup. Besides, the devices_subsys_id is read from memory, whilst there's a enum-ed constant for it. Optimize this part a bit: 1. Get the subsys_stats form the task and be done - no 2 extra dereferences, 2. Use the device_subsys_id constant, not the value from memory (i.e. one less dereference). Found while preparing 2.6.26 OpenVZ port. Signed-off-by: Pavel Emelyanov Acked-by: Serge Hallyn Acked-by: Paul Menage Cc: Balbir Singh Cc: James Morris Cc: Chris Wright Cc: Stephen Smalley Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- security/device_cgroup.c | 10 ++++------ 1 file changed, 4 insertions(+), 6 deletions(-) diff --git a/security/device_cgroup.c b/security/device_cgroup.c index 15f2f8003ba3..f9941a769738 100644 --- a/security/device_cgroup.c +++ b/security/device_cgroup.c @@ -506,7 +506,6 @@ struct cgroup_subsys devices_subsys = { int devcgroup_inode_permission(struct inode *inode, int mask) { - struct cgroup *cgroup; struct dev_cgroup *dev_cgroup; struct dev_whitelist_item *wh; @@ -515,8 +514,8 @@ int devcgroup_inode_permission(struct inode *inode, int mask) return 0; if (!S_ISBLK(inode->i_mode) && !S_ISCHR(inode->i_mode)) return 0; - cgroup = task_cgroup(current, devices_subsys.subsys_id); - dev_cgroup = cgroup_to_devcgroup(cgroup); + dev_cgroup = css_to_devcgroup(task_subsys_state(current, + devices_subsys_id)); if (!dev_cgroup) return 0; @@ -547,12 +546,11 @@ acc_check: int devcgroup_inode_mknod(int mode, dev_t dev) { - struct cgroup *cgroup; struct dev_cgroup *dev_cgroup; struct dev_whitelist_item *wh; - cgroup = task_cgroup(current, devices_subsys.subsys_id); - dev_cgroup = cgroup_to_devcgroup(cgroup); + dev_cgroup = css_to_devcgroup(task_subsys_state(current, + devices_subsys_id)); if (!dev_cgroup) return 0; -- 2.20.1