[PATCH v2 1/6] cgroup: initialize cgrp->dentry before css_alloc()

Li Zefan
2013-01-24T06:31:15Z

With this change, we're guaranteed that cgroup_path() won't see NULL
cgrp->dentry, and thus we can remove the NULL check in it.

(Well, it's not true, because dummptop.dentry is always NULL)

Signed-off-by: Li Zefan <lizefan@huawei.com>
---
kernel/cgroup.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index ad3359f..b9a76e2 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -1767,7 +1767,7 @@ int cgroup_path(const struct cgroup *cgrp, char *buf, int buflen)
rcu_lockdep_assert(rcu_read_lock_held() || cgroup_lock_is_held(),
"cgroup_path() called without proper locking");

- if (!dentry || cgrp == dummytop) {
+ if (cgrp == dummytop) {
/*
* Inactive subsystems have no dentry for their root
* cgroup
@@ -4153,6 +4153,9 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry,

init_cgroup_housekeeping(cgrp);

+ dentry->d_fsdata = cgrp;
+ cgrp->dentry = dentry;
+
cgrp->parent = parent;
cgrp->root = parent->root;
cgrp->top_cgroup = parent->top_cgroup;
@@ -4190,8 +4193,6 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry,
lockdep_assert_held(&dentry->d_inode->i_mutex);

/* allocation complete, commit to creation */
- dentry->d_fsdata = cgrp;
- cgrp->dentry = dentry;
list_add_tail(&cgrp->allcg_node, &root->allcg_list);
list_add_tail_rcu(&cgrp->sibling, &cgrp->parent->children);
root->number_of_cgroups++;
--
1.8.0.2