cgroup: separate out cset_group_from_root() from task_cgroup_from_root()
This will be used by the planned migration path update.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 5def4a8..23e3a8c 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -758,25 +758,15 @@
cgroup_free_root(root);
}
-/*
- * Return the cgroup for "task" from the given hierarchy. Must be
- * called with cgroup_mutex and css_set_rwsem held.
- */
-static struct cgroup *task_cgroup_from_root(struct task_struct *task,
+/* look up cgroup associated with given css_set on the specified hierarchy */
+static struct cgroup *cset_cgroup_from_root(struct css_set *cset,
struct cgroupfs_root *root)
{
- struct css_set *cset;
struct cgroup *res = NULL;
lockdep_assert_held(&cgroup_mutex);
lockdep_assert_held(&css_set_rwsem);
- /*
- * No need to lock the task - since we hold cgroup_mutex the
- * task can't change groups, so the only thing that can happen
- * is that it exits and its css is set back to init_css_set.
- */
- cset = task_css_set(task);
if (cset == &init_css_set) {
res = &root->top_cgroup;
} else {
@@ -797,6 +787,21 @@
}
/*
+ * Return the cgroup for "task" from the given hierarchy. Must be
+ * called with cgroup_mutex and css_set_rwsem held.
+ */
+static struct cgroup *task_cgroup_from_root(struct task_struct *task,
+ struct cgroupfs_root *root)
+{
+ /*
+ * No need to lock the task - since we hold cgroup_mutex the
+ * task can't change groups, so the only thing that can happen
+ * is that it exits and its css is set back to init_css_set.
+ */
+ return cset_cgroup_from_root(task_css_set(task), root);
+}
+
+/*
* There is one global cgroup mutex. We also require taking
* task_lock() when dereferencing a task's cgroup subsys pointers.
* See "The task_lock() exception", at the end of this comment.