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device_cgroup: use css_has_online_children() instead of has_children()

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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>
Acked-by: Aristeu Rozanski <aris@redhat.com>
Acked-by: Serge Hallyn <serge.hallyn@ubuntu.com>
Acked-by: Li Zefan <lizefan@huawei.com>
This commit is contained in:
Tejun Heo 2014-05-16 13:22:52 -04:00
parent f3d4650015
commit 7a3bb24f7c
1 changed files with 2 additions and 17 deletions
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19
security/device_cgroup.c
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@ -587,21 +587,6 @@ static int propagate_exception(struct dev_cgroup *devcg_root,
return rc; 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. * Modify the exception list using allow/deny rules.
* CAP_SYS_ADMIN is needed for this. It's at least separate from CAP_MKNOD * CAP_SYS_ADMIN is needed for this. It's at least separate from CAP_MKNOD
@ -634,7 +619,7 @@ static int devcgroup_update_access(struct dev_cgroup *devcgroup,
case 'a': case 'a':
switch (filetype) { switch (filetype) {
case DEVCG_ALLOW: case DEVCG_ALLOW:
if (has_children(devcgroup)) if (css_has_online_children(&devcgroup->css))
return -EINVAL; return -EINVAL;
if (!may_allow_all(parent)) if (!may_allow_all(parent))
@ -650,7 +635,7 @@ static int devcgroup_update_access(struct dev_cgroup *devcgroup,
return rc; return rc;
break; break;
case DEVCG_DENY: case DEVCG_DENY:
if (has_children(devcgroup)) if (css_has_online_children(&devcgroup->css))
return -EINVAL; return -EINVAL;
dev_exception_clean(devcgroup); dev_exception_clean(devcgroup);