[PATCH 13/14] device_cgroup: use css_has_online_children() instead of has_children()

Tejun Heo
2014-05-09T21:31:59Z

devcgroup_update_access() wants to know whether there are child
cgroups which are online and visible to userland and has_children()
may return false positive. Replace it with css_has_online_children().

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Aristeu Rozanski <aris@redhat.com>
Cc: Serge Hallyn <serge.hallyn@ubuntu.com>
---
security/device_cgroup.c | 19 ++-----------------
1 file changed, 2 insertions(+), 17 deletions(-)

diff --git a/security/device_cgroup.c b/security/device_cgroup.c
index 75b4b18..22de334 100644
--- a/security/device_cgroup.c
+++ b/security/device_cgroup.c
@@ -475,21 +475,6 @@ static int propagate_exception(struct dev_cgroup *devcg_root,
return rc;
}

-static inline bool has_children(struct dev_cgroup *devcgroup)
-{
- bool ret;
-
- /*
- * FIXME: There may be lingering offline csses and this function
- * may return %true when there isn't any userland-visible child
- * which is incorrect for our purposes.
- */
- rcu_read_lock();
- ret = css_next_child(NULL, &devcgroup->css);
- rcu_read_unlock();
- return ret;
-}
-
/*
* Modify the exception list using allow/deny rules.
* CAP_SYS_ADMIN is needed for this. It's at least separate from CAP_MKNOD
@@ -522,7 +507,7 @@ static int devcgroup_update_access(struct dev_cgroup *devcgroup,
case 'a':
switch (filetype) {
case DEVCG_ALLOW:
- if (has_children(devcgroup))
+ if (css_has_online_children(&devcgroup->css))
return -EINVAL;

if (!may_allow_all(parent))
@@ -538,7 +523,7 @@ static int devcgroup_update_access(struct dev_cgroup *devcgroup,
return rc;
break;
case DEVCG_DENY:
- if (has_children(devcgroup))
+ if (css_has_online_children(&devcgroup->css))
return -EINVAL;

dev_exception_clean(devcgroup);
--
1.9.0