cgroup: Export cgroup.kill from cgroupv2 to cgroupv1

hulk inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I4X0YD?from=project-issue
CVE: NA

--------

Export cgroup.kill feature from cgroupv2 to cgroupv1. Therefore, user
can kill all process in one cgroup and its subcgroups instead of kill them
one by one.
Signed-off-by: NLu Jialin <lujialin4@huawei.com>
Reviewed-by: NXiu Jianfeng <xiujianfeng@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

kernel/cgroup/cgroup-internal.h

@@ -266,6 +266,9 @@ int cgroup_show_path(struct seq_file *sf, struct kernfs_node *kf_node,
 int __cgroup_task_count(const struct cgroup *cgrp);
 int cgroup_task_count(const struct cgroup *cgrp);
 
+ssize_t cgroup_kill_write(struct kernfs_open_file *of, char *buf, size_t nbytes,
+			  loff_t off);
+
 /*
  * rstat.c
  */

kernel/cgroup/cgroup-v1.c

@@ -658,6 +658,11 @@ struct cftype cgroup1_base_files[] = {
 		.write = cgroup_release_agent_write,
 		.max_write_len = PATH_MAX - 1,
 	},
+	{
+		.name = "cgroup.kill",
+		.flags = CFTYPE_NOT_ON_ROOT,
+		.write = cgroup_kill_write,
+	},
 	{ }	/* terminate */
 };
 

kernel/cgroup/cgroup.c

@@ -3808,8 +3808,8 @@ static void cgroup_kill(struct cgroup *cgrp)
 		__cgroup_kill(dsct);
 }
 
-static ssize_t cgroup_kill_write(struct kernfs_open_file *of, char *buf,
-				 size_t nbytes, loff_t off)
+ssize_t cgroup_kill_write(struct kernfs_open_file *of, char *buf, size_t nbytes,
+			  loff_t off)
 {
 	ssize_t ret = 0;
 	int kill;