cgroup, cpuset: replace move_member_tasks_to_cpuset() with cgroup_transfer_tasks()
When a cpuset becomes empty (no CPU or memory), its tasks are
transferred with the nearest ancestor with execution resources. This
is implemented using cgroup_scan_tasks() with a callback which grabs
cgroup_mutex and invokes cgroup_attach_task() on each task.
Both cgroup_mutex and cgroup_attach_task() are scheduled to be
unexported. Implement cgroup_transfer_tasks() in cgroup proper which
is essentially the same as move_member_tasks_to_cpuset() except that
it takes cgroups instead of cpusets and @to comes before @from like
normal functions with those arguments, and replace
move_member_tasks_to_cpuset() with it.
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 4aee5bd..147d7cc 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -3269,6 +3269,34 @@
return 0;
}
+static void cgroup_transfer_one_task(struct task_struct *task,
+ struct cgroup_scanner *scan)
+{
+ struct cgroup *new_cgroup = scan->data;
+
+ cgroup_lock();
+ cgroup_attach_task(new_cgroup, task, false);
+ cgroup_unlock();
+}
+
+/**
+ * cgroup_trasnsfer_tasks - move tasks from one cgroup to another
+ * @to: cgroup to which the tasks will be moved
+ * @from: cgroup in which the tasks currently reside
+ */
+int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from)
+{
+ struct cgroup_scanner scan;
+
+ scan.cg = from;
+ scan.test_task = NULL; /* select all tasks in cgroup */
+ scan.process_task = cgroup_transfer_one_task;
+ scan.heap = NULL;
+ scan.data = to;
+
+ return cgroup_scan_tasks(&scan);
+}
+
/*
* Stuff for reading the 'tasks'/'procs' files.
*