cgroup: delay the clearing of cgrp->kn->priv

[deliverable/linux.git] / kernel / cgroup.c

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 50b94113f4f7a69f8c3be4b8297beffde67254e4..bf30076664ca4a281af97873b8b5f172cdb7bcbb 100644 (file)
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -4396,6 +4396,15 @@ static void css_release_work_fn(struct work_struct *work)
                /* cgroup release path */
                cgroup_idr_remove(&cgrp->root->cgroup_idr, cgrp->id);
                cgrp->id = -1;
+
+               /*
+                * There are two control paths which try to determine
+                * cgroup from dentry without going through kernfs -
+                * cgroupstats_build() and css_tryget_online_from_dir().
+                * Those are supported by RCU protecting clearing of
+                * cgrp->kn->priv backpointer.
+                */
+               RCU_INIT_POINTER(*(void __rcu __force **)&cgrp->kn->priv, NULL);
        }
 
        mutex_unlock(&cgroup_mutex);
@@ -4834,16 +4843,6 @@ static int cgroup_rmdir(struct kernfs_node *kn)
 
        cgroup_kn_unlock(kn);
 
-       /*
-        * There are two control paths which try to determine cgroup from
-        * dentry without going through kernfs - cgroupstats_build() and
-        * css_tryget_online_from_dir().  Those are supported by RCU
-        * protecting clearing of cgrp->kn->priv backpointer, which should
-        * happen after all files under it have been removed.
-        */
-       if (!ret)
-               RCU_INIT_POINTER(*(void __rcu __force **)&kn->priv, NULL);
-
        cgroup_put(cgrp);
        return ret;
 }
@@ -5430,7 +5429,7 @@ struct cgroup_subsys_state *css_tryget_online_from_dir(struct dentry *dentry,
        /*
         * This path doesn't originate from kernfs and @kn could already
         * have been or be removed at any point.  @kn->priv is RCU
-        * protected for this access.  See cgroup_rmdir() for details.
+        * protected for this access.  See css_release_work_fn() for details.
         */
        cgrp = rcu_dereference(kn->priv);
        if (cgrp)