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 <tj@kernel.org>
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Aristeu Rozanski <aris@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
diff --git a/security/device_cgroup.c b/security/device_cgroup.c
index ddf3c70..16c9e10 100644
--- a/security/device_cgroup.c
+++ b/security/device_cgroup.c
@@ -185,36 +185,59 @@
__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 @@
.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,