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Commit 1909554c authored by Aristeu Rozanski's avatar Aristeu Rozanski Committed by Tejun Heo
Browse files

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: default avatarTejun Heo <tj@kernel.org>
Acked-by: default avatarSerge Hallyn <serge.hallyn@canonical.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: default avatarAristeu Rozanski <aris@redhat.com>
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
parent c39a2a30

security/device_cgroup.c

+42 −17
Original line number Diff line number Diff line
@@ -185,36 +185,59 @@ static void dev_exception_clean(struct dev_cgroup *dev_cgroup) 
	__dev_exception_clean(dev_cgroup);

}



/*

 * called from kernel/cgroup.c with cgroup_lock() held.

/**

 * 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 struct cgroup_subsys_state *devcgroup_css_alloc(struct cgroup *cgroup)

static int devcgroup_online(struct cgroup *cgroup)

{

	struct dev_cgroup *dev_cgroup, *parent_dev_cgroup;

	struct cgroup *parent_cgroup;

	int ret;

	struct dev_cgroup *dev_cgroup, *parent_dev_cgroup = NULL;

	int ret = 0;



	dev_cgroup = kzalloc(sizeof(*dev_cgroup), GFP_KERNEL);

	if (!dev_cgroup)

		return ERR_PTR(-ENOMEM);

	INIT_LIST_HEAD(&dev_cgroup->exceptions);

	parent_cgroup = cgroup->parent;

	mutex_lock(&devcgroup_mutex);

	dev_cgroup = cgroup_to_devcgroup(cgroup);

	if (cgroup->parent)

		parent_dev_cgroup = cgroup_to_devcgroup(cgroup->parent);



	if (parent_cgroup == NULL)

	if (parent_dev_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);

		if (!ret)

			dev_cgroup->behavior = parent_dev_cgroup->behavior;

	}

	mutex_unlock(&devcgroup_mutex);

		if (ret) {

			kfree(dev_cgroup);

			return ERR_PTR(ret);



	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;

	struct cgroup *parent_cgroup;



	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;



	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,