[PATCH 1/3] cgroups: Add an API to attach a task to current task's cgroup

[Sridhar Samudrala <samudrala.sridhar@gmail.com>]

Add a new kernel API to attach a task to current task's cgroup
in all the active hierarchies.

Signed-off-by: Sridhar Samudrala <sri@us.ibm.com>

diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -570,6 +570,7 @@ struct task_struct *cgroup_iter_next(struct cgroup *cgrp,
 void cgroup_iter_end(struct cgroup *cgrp, struct cgroup_iter *it);
 int cgroup_scan_tasks(struct cgroup_scanner *scan);
 int cgroup_attach_task(struct cgroup *, struct task_struct *);
+int cgroup_attach_task_current_cg(struct task_struct *);
 
 /*
  * CSS ID is ID for cgroup_subsys_state structs under subsys. This only works
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 6d870f2..6cfeb06 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -1788,6 +1788,29 @@ out:
 	return retval;
 }
 
+/**
+ * cgroup_attach_task_current_cg - attach task 'tsk' to current task's cgroup
+ * @tsk: the task to be attached
+ */
+int cgroup_attach_task_current_cg(struct task_struct *tsk)
+{
+	struct cgroupfs_root *root;
+	struct cgroup *cur_cg;
+	int retval = 0;
+
+	cgroup_lock();
+	for_each_active_root(root) {
+		cur_cg = task_cgroup_from_root(current, root);
+		retval = cgroup_attach_task(cur_cg, tsk);
+		if (retval)
+			break;
+	}
+	cgroup_unlock();
+
+	return retval;
+}
+EXPORT_SYMBOL_GPL(cgroup_attach_task_current_cg);
+
 /*
  * Attach task with pid 'pid' to cgroup 'cgrp'. Call with cgroup_mutex
  * held. May take task_lock of task