From 1909554c9715e4d032497993bb56f2726bfa89ae Mon Sep 17 00:00:00 2001 From: Aristeu Rozanski Date: Fri, 15 Feb 2013 11:55:46 -0500 Subject: [PATCH 1/1] devcg: use css_online and css_offline Allocate resources and change behavior only when online. This is needed in order to determine if a node is suitable for hierarchy propagation or if it's being removed. Locking: Both functions take devcgroup_mutex to make changes to device_cgroup structure. Hierarchy propagation will also take devcgroup_mutex before walking the tree while walking the tree itself is protected by rcu lock. Acked-by: Tejun Heo Acked-by: Serge Hallyn Cc: Tejun Heo Cc: Serge Hallyn Signed-off-by: Aristeu Rozanski Signed-off-by: Tejun Heo --- security/device_cgroup.c | 59 ++++++++++++++++++++++++++++------------ 1 file changed, 42 insertions(+), 17 deletions(-) diff --git a/security/device_cgroup.c b/security/device_cgroup.c index ddf3c709c0c2..16c9e1069be6 100644 --- a/security/device_cgroup.c +++ b/security/device_cgroup.c @@ -185,36 +185,59 @@ static void dev_exception_clean(struct dev_cgroup *dev_cgroup) __dev_exception_clean(dev_cgroup); } +/** + * devcgroup_online - initializes devcgroup's behavior and exceptions based on + * parent's + * @cgroup: cgroup getting online + * returns 0 in case of success, error code otherwise + */ +static int devcgroup_online(struct cgroup *cgroup) +{ + struct dev_cgroup *dev_cgroup, *parent_dev_cgroup = NULL; + int ret = 0; + + mutex_lock(&devcgroup_mutex); + dev_cgroup = cgroup_to_devcgroup(cgroup); + if (cgroup->parent) + parent_dev_cgroup = cgroup_to_devcgroup(cgroup->parent); + + if (parent_dev_cgroup == NULL) + dev_cgroup->behavior = DEVCG_DEFAULT_ALLOW; + else { + ret = dev_exceptions_copy(&dev_cgroup->exceptions, + &parent_dev_cgroup->exceptions); + if (!ret) + dev_cgroup->behavior = parent_dev_cgroup->behavior; + } + mutex_unlock(&devcgroup_mutex); + + return ret; +} + +static void devcgroup_offline(struct cgroup *cgroup) +{ + struct dev_cgroup *dev_cgroup = cgroup_to_devcgroup(cgroup); + + mutex_lock(&devcgroup_mutex); + dev_cgroup->behavior = DEVCG_DEFAULT_NONE; + mutex_unlock(&devcgroup_mutex); +} + /* * called from kernel/cgroup.c with cgroup_lock() held. */ static struct cgroup_subsys_state *devcgroup_css_alloc(struct cgroup *cgroup) { - struct dev_cgroup *dev_cgroup, *parent_dev_cgroup; + struct dev_cgroup *dev_cgroup; struct cgroup *parent_cgroup; - int ret; dev_cgroup = kzalloc(sizeof(*dev_cgroup), GFP_KERNEL); if (!dev_cgroup) return ERR_PTR(-ENOMEM); INIT_LIST_HEAD(&dev_cgroup->exceptions); + dev_cgroup->behavior = DEVCG_DEFAULT_NONE; parent_cgroup = cgroup->parent; - if (parent_cgroup == NULL) - dev_cgroup->behavior = DEVCG_DEFAULT_ALLOW; - else { - parent_dev_cgroup = cgroup_to_devcgroup(parent_cgroup); - mutex_lock(&devcgroup_mutex); - ret = dev_exceptions_copy(&dev_cgroup->exceptions, - &parent_dev_cgroup->exceptions); - dev_cgroup->behavior = parent_dev_cgroup->behavior; - mutex_unlock(&devcgroup_mutex); - if (ret) { - kfree(dev_cgroup); - return ERR_PTR(ret); - } - } - return &dev_cgroup->css; } @@ -587,6 +610,8 @@ struct cgroup_subsys devices_subsys = { .can_attach = devcgroup_can_attach, .css_alloc = devcgroup_css_alloc, .css_free = devcgroup_css_free, + .css_online = devcgroup_online, + .css_offline = devcgroup_offline, .subsys_id = devices_subsys_id, .base_cftypes = dev_cgroup_files, -- 2.20.1