device_cgroup: introduce dev_whitelist_clean()

This function cleans all the items in a whitelist and will be used by the next
patches.

Signed-off-by: Aristeu Rozanski <aris@redhat.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Li Zefan <lizefan@huawei.com>
Cc: James Morris <jmorris@namei.org>
Cc: Pavel Emelyanov <xemul@openvz.org>
Acked-by: Serge E. Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

security/device_cgroup.c

diff --git a/security/device_cgroup.c b/security/device_cgroup.c
index e3ce02a..5b36b62 100644
--- a/security/device_cgroup.c
+++ b/security/device_cgroup.c
@@ -154,6 +154,22 @@
 	}
 }
 
+/**
+ * dev_whitelist_clean - frees all entries of the whitelist
+ * @dev_cgroup: dev_cgroup with the whitelist to be cleaned
+ *
+ * called under devcgroup_mutex
+ */
+static void dev_whitelist_clean(struct dev_cgroup *dev_cgroup)
+{
+	struct dev_whitelist_item *wh, *tmp;
+
+	list_for_each_entry_safe(wh, tmp, &dev_cgroup->whitelist, list) {
+		list_del(&wh->list);
+		kfree(wh);
+	}
+}
+
 /*
  * called from kernel/cgroup.c with cgroup_lock() held.
  */
@@ -200,13 +216,9 @@
 static void devcgroup_destroy(struct cgroup *cgroup)
 {
 	struct dev_cgroup *dev_cgroup;
-	struct dev_whitelist_item *wh, *tmp;
 
 	dev_cgroup = cgroup_to_devcgroup(cgroup);
-	list_for_each_entry_safe(wh, tmp, &dev_cgroup->whitelist, list) {
-		list_del(&wh->list);
-		kfree(wh);
-	}
+	dev_whitelist_clean(dev_cgroup);
 	kfree(dev_cgroup);
 }