cgroup/cpuset: introduce cpuset-v1.c

This patch introduces the cgroup/cpuset-v1.c source file which will be
used for all legacy (cgroup v1) cpuset cgroup code. It also introduces
cgroup/cpuset-internal.h to keep declarations shared between
cgroup/cpuset.c and cpuset/cpuset-v1.c.

As of now, let's compile it if CONFIG_CPUSET is set. Later on it can be
switched to use a separate config option, so that the legacy code won't be
compiled if not required.
Signed-off-by: Chen Ridong <chenridong@huawei.com>
Acked-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

MAINTAINERS

@@ -5698,6 +5698,8 @@ S:	Maintained
 T:	git git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup.git
 F:	Documentation/admin-guide/cgroup-v1/cpusets.rst
 F:	include/linux/cpuset.h
+F:	kernel/cgroup/cpuset-internal.h
+F:	kernel/cgroup/cpuset-v1.c
 F:	kernel/cgroup/cpuset.c
 F:	tools/testing/selftests/cgroup/test_cpuset.c
 F:	tools/testing/selftests/cgroup/test_cpuset_prs.sh

kernel/cgroup/Makefile

@@ -4,6 +4,6 @@ obj-y := cgroup.o rstat.o namespace.o cgroup-v1.o freezer.o
 obj-$(CONFIG_CGROUP_FREEZER) += legacy_freezer.o
 obj-$(CONFIG_CGROUP_PIDS) += pids.o
 obj-$(CONFIG_CGROUP_RDMA) += rdma.o
-obj-$(CONFIG_CPUSETS) += cpuset.o
+obj-$(CONFIG_CPUSETS) += cpuset.o cpuset-v1.o
 obj-$(CONFIG_CGROUP_MISC) += misc.o
 obj-$(CONFIG_CGROUP_DEBUG) += debug.o

kernel/cgroup/cpuset-internal.h

+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#ifndef __CPUSET_INTERNAL_H
+#define __CPUSET_INTERNAL_H
+
+#endif /* __CPUSET_INTERNAL_H */

kernel/cgroup/cpuset-v1.c

+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#include "cpuset-internal.h"