Merge branch 'for-3.13-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj...

[karo-tx-linux.git] / kernel / cgroup.c

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 8b729c278b649c7c016786f6dac9886290ce794f..bc1dcabe92176636baf79c7ef52e597422aeaf75 100644 (file)
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -890,6 +890,16 @@ static void cgroup_diput(struct dentry *dentry, struct inode *inode)
                struct cgroup *cgrp = dentry->d_fsdata;
 
                BUG_ON(!(cgroup_is_dead(cgrp)));
+
+               /*
+                * XXX: cgrp->id is only used to look up css's.  As cgroup
+                * and css's lifetimes will be decoupled, it should be made
+                * per-subsystem and moved to css->id so that lookups are
+                * successful until the target css is released.
+                */
+               idr_remove(&cgrp->root->cgroup_idr, cgrp->id);
+               cgrp->id = -1;
+
                call_rcu(&cgrp->rcu_head, cgroup_free_rcu);
        } else {
                struct cfent *cfe = __d_cfe(dentry);
@@ -4268,6 +4278,7 @@ static void css_release(struct percpu_ref *ref)
        struct cgroup_subsys_state *css =
                container_of(ref, struct cgroup_subsys_state, refcnt);
 
+       rcu_assign_pointer(css->cgroup->subsys[css->ss->subsys_id], NULL);
        call_rcu(&css->rcu_head, css_free_rcu_fn);
 }
 
@@ -4426,14 +4437,6 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry,
        list_add_tail_rcu(&cgrp->sibling, &cgrp->parent->children);
        root->number_of_cgroups++;
 
-       /* each css holds a ref to the cgroup's dentry and the parent css */
-       for_each_root_subsys(root, ss) {
-               struct cgroup_subsys_state *css = css_ar[ss->subsys_id];
-
-               dget(dentry);
-               css_get(css->parent);
-       }
-
        /* hold a ref to the parent's dentry */
        dget(parent->dentry);
 
@@ -4445,6 +4448,13 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry,
                if (err)
                        goto err_destroy;
 
+               /* each css holds a ref to the cgroup's dentry and parent css */
+               dget(dentry);
+               css_get(css->parent);
+
+               /* mark it consumed for error path */
+               css_ar[ss->subsys_id] = NULL;
+
                if (ss->broken_hierarchy && !ss->warned_broken_hierarchy &&
                    parent->parent) {
                        pr_warning("cgroup: %s (%d) created nested cgroup for controller \"%s\" which has incomplete hierarchy support. Nested cgroups may change behavior in the future.\n",
@@ -4491,6 +4501,14 @@ err_free_cgrp:
        return err;
 
 err_destroy:
+       for_each_root_subsys(root, ss) {
+               struct cgroup_subsys_state *css = css_ar[ss->subsys_id];
+
+               if (css) {
+                       percpu_ref_cancel_init(&css->refcnt);
+                       ss->css_free(css);
+               }
+       }
        cgroup_destroy_locked(cgrp);
        mutex_unlock(&cgroup_mutex);
        mutex_unlock(&dentry->d_inode->i_mutex);
@@ -4652,8 +4670,12 @@ static int cgroup_destroy_locked(struct cgroup *cgrp)
         * will be invoked to perform the rest of destruction once the
         * percpu refs of all css's are confirmed to be killed.
         */
-       for_each_root_subsys(cgrp->root, ss)
-               kill_css(cgroup_css(cgrp, ss));
+       for_each_root_subsys(cgrp->root, ss) {
+               struct cgroup_subsys_state *css = cgroup_css(cgrp, ss);
+
+               if (css)
+                       kill_css(css);
+       }
 
        /*
         * Mark @cgrp dead.  This prevents further task migration and child
@@ -4722,14 +4744,6 @@ static void cgroup_destroy_css_killed(struct cgroup *cgrp)
        /* delete this cgroup from parent->children */
        list_del_rcu(&cgrp->sibling);
 
-       /*
-        * We should remove the cgroup object from idr before its grace
-        * period starts, so we won't be looking up a cgroup while the
-        * cgroup is being freed.
-        */
-       idr_remove(&cgrp->root->cgroup_idr, cgrp->id);
-       cgrp->id = -1;
-
        dput(d);
 
        set_bit(CGRP_RELEASABLE, &parent->flags);