1 files changed, 20 insertions, 3 deletions

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 0249f4be9b5c..4fd90e129772 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -23,6 +23,7 @@
  */
 
 #include <linux/cgroup.h>
+#include <linux/module.h>
 #include <linux/ctype.h>
 #include <linux/errno.h>
 #include <linux/fs.h>
@@ -166,6 +167,20 @@ static DEFINE_SPINLOCK(hierarchy_id_lock);
  */
 static int need_forkexit_callback __read_mostly;
 
+#ifdef CONFIG_PROVE_LOCKING
+int cgroup_lock_is_held(void)
+{
+        return lockdep_is_held(&cgroup_mutex);
+}
+#else /* #ifdef CONFIG_PROVE_LOCKING */
+int cgroup_lock_is_held(void)
+{
+        return mutex_is_locked(&cgroup_mutex);
+}
+#endif /* #else #ifdef CONFIG_PROVE_LOCKING */
+
+EXPORT_SYMBOL_GPL(cgroup_lock_is_held);
+
 /* convenient tests for these bits */
 inline int cgroup_is_removed(const struct cgroup *cgrp)
 {
@@ -2468,7 +2483,6 @@ static struct cgroup_pidlist *cgroup_pidlist_find(struct cgroup *cgrp,
                         /* make sure l doesn't vanish out from under us */
                         down_write(&l->mutex);
                         mutex_unlock(&cgrp->pidlist_mutex);
-                        l->use_count++;
                         return l;
                 }
         }
@@ -2937,14 +2951,17 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry,
 
         for_each_subsys(root, ss) {
                 struct cgroup_subsys_state *css = ss->create(ss, cgrp);
+
                 if (IS_ERR(css)) {
                         err = PTR_ERR(css);
                         goto err_destroy;
                 }
                 init_cgroup_css(css, ss, cgrp);
-                if (ss->use_id)
-                        if (alloc_css_id(ss, parent, cgrp))
+                if (ss->use_id) {
+                        err = alloc_css_id(ss, parent, cgrp);
+                        if (err)
                                 goto err_destroy;
+                }
                 /* At error, ->destroy() callback has to free assigned ID. */
         }