[PATCH v2] cgroup-v1: add disabled controller check in cgroup1_parse_param()

[Chen Zhou <chenzhou10-hv44wF8Li93QT0dZR+AlfA@public.gmane.org>]

When mounting a cgroup hierarchy with disabled controller in cgroup v1,
all available controllers will be attached.

Add disabled controller check in cgroup1_parse_param() and return directly
if the specified controller is disabled.

Signed-off-by: Chen Zhou <chenzhou10-hv44wF8Li93QT0dZR+AlfA@public.gmane.org>
---
Changes in v2:
- Fix line over 80 characters warning.
---
 kernel/cgroup/cgroup-v1.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/kernel/cgroup/cgroup-v1.c b/kernel/cgroup/cgroup-v1.c
index 191c329e482a..5190c42fea8b 100644
--- a/kernel/cgroup/cgroup-v1.c
+++ b/kernel/cgroup/cgroup-v1.c
@@ -915,6 +915,9 @@ int cgroup1_parse_param(struct fs_context *fc, struct fs_parameter *param)
 		for_each_subsys(ss, i) {
 			if (strcmp(param->key, ss->legacy_name))
 				continue;
+			if (!cgroup_ssid_enabled(i) || cgroup1_ssid_disabled(i))
+				return invalfc(fc, "Disabled controller '%s'",
+					       param->key);
 			ctx->subsys_mask |= (1 << i);
 			return 0;
 		}
-- 
2.20.1