[RFC PATCH v4 18/28] sched/rt: Remove support for cgroups-v1

[Yuri Andriaccio <yurand2000@gmail.com>]

Disable control files for cgroups-v1, and allow only cgroups-v2. This
should simplify maintaining the code, also because cgroups-v1 are
deprecated.

Set the default rt-cgroups runtime to zero, otherwise a cgroup-v1 kernel
will not be able to start SCHED_DEADLINE tasks. The bandwidth for
rt-cgroups must then be manually assigned after the kernel boots.

Signed-off-by: Yuri Andriaccio <yurand2000@gmail.com>
---
 kernel/sched/core.c | 20 +-------------------
 1 file changed, 1 insertion(+), 19 deletions(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 6278f203b4..cfb39050a2 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -8693,7 +8693,7 @@ void __init sched_init(void)
 
 #ifdef CONFIG_RT_GROUP_SCHED
 	init_dl_bandwidth(&root_task_group.dl_bandwidth,
-			global_rt_period(), global_rt_runtime());
+			global_rt_period(), 0);
 #endif /* CONFIG_RT_GROUP_SCHED */
 
 #ifdef CONFIG_CGROUP_SCHED
@@ -10032,20 +10032,6 @@ static struct cftype cpu_legacy_files[] = {
 };
 
 #ifdef CONFIG_RT_GROUP_SCHED
-static struct cftype rt_group_files[] = {
-	{
-		.name = "rt_runtime_us",
-		.read_s64 = cpu_rt_runtime_read,
-		.write_s64 = cpu_rt_runtime_write,
-	},
-	{
-		.name = "rt_period_us",
-		.read_u64 = cpu_rt_period_read_uint,
-		.write_u64 = cpu_rt_period_write_uint,
-	},
-	{ }	/* Terminate */
-};
-
 # ifdef CONFIG_RT_GROUP_SCHED_DEFAULT_DISABLED
 DEFINE_STATIC_KEY_FALSE(rt_group_sched);
 # else
@@ -10071,10 +10057,6 @@ __setup("rt_group_sched=", setup_rt_group_sched);
 
 static int __init cpu_rt_group_init(void)
 {
-	if (!rt_group_sched_enabled())
-		return 0;
-
-	WARN_ON(cgroup_add_legacy_cftypes(&cpu_cgrp_subsys, rt_group_files));
 	return 0;
 }
 subsys_initcall(cpu_rt_group_init);
-- 
2.51.0