[PATCH v2 -next 10/11] cgroup/cpuset: guard cpuset-v1 code under CONFIG_CPUSETS_V1

Chen Ridong
2024-08-26T13:34:56Z

This patch introduces CONFIG_CPUSETS_V1 and guard cpuset-v1 code under
CONFIG_CPUSETS_V1. The default value of CONFIG_CPUSETS_V1 is N, so that
user who adopted v2 don't have 'pay' for cpuset v1.

Signed-off-by: Chen Ridong <chenridong@huawei.com>
---
include/linux/cpuset.h | 4 ++++
init/Kconfig | 13 +++++++++++++
kernel/cgroup/Makefile | 3 ++-
kernel/cgroup/cpuset-internal.h | 13 +++++++++++++
kernel/cgroup/cpuset.c | 2 ++
5 files changed, 34 insertions(+), 1 deletion(-)

diff --git a/include/linux/cpuset.h b/include/linux/cpuset.h
index 2a6981eeebf8..835e7b793f6a 100644
--- a/include/linux/cpuset.h
+++ b/include/linux/cpuset.h
@@ -99,6 +99,7 @@ static inline bool cpuset_zone_allowed(struct zone *z, gfp_t gfp_mask)
extern int cpuset_mems_allowed_intersects(const struct task_struct *tsk1,
const struct task_struct *tsk2);

+#ifdef CONFIG_CPUSETS_V1
#define cpuset_memory_pressure_bump() \
do { \
if (cpuset_memory_pressure_enabled) \
@@ -106,6 +107,9 @@ extern int cpuset_mems_allowed_intersects(const struct task_struct *tsk1,
} while (0)
extern int cpuset_memory_pressure_enabled;
extern void __cpuset_memory_pressure_bump(void);
+#else
+static inline void cpuset_memory_pressure_bump(void) { }
+#endif

extern void cpuset_task_status_allowed(struct seq_file *m,
struct task_struct *task);
diff --git a/init/Kconfig b/init/Kconfig
index a465ea9525bd..8bf091354bea 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1143,6 +1143,19 @@ config CPUSETS

Say N if unsure.

+config CPUSETS_V1
+ bool "Legacy cgroup v1 cpusets controller"
+ depends on CPUSETS
+ default n
+ help
+ Legacy cgroup v1 cpusets controller which has been deprecated by
+ cgroup v2 implementation. The v1 is there for legacy applications
+ which haven't migrated to the new cgroup v2 interface yet. If you
+ do not have any such application then you are completely fine leaving
+ this option disabled.
+
+ Say N if unsure.
+
config PROC_PID_CPUSET
bool "Include legacy /proc/<pid>/cpuset file"
depends on CPUSETS
diff --git a/kernel/cgroup/Makefile b/kernel/cgroup/Makefile
index 005ac4c675cb..a5c9359d516f 100644
--- a/kernel/cgroup/Makefile
+++ b/kernel/cgroup/Makefile
@@ -4,6 +4,7 @@ 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 cpuset-v1.o
+obj-$(CONFIG_CPUSETS) += cpuset.o
+obj-$(CONFIG_CPUSETS_V1) += cpuset-v1.o
obj-$(CONFIG_CGROUP_MISC) += misc.o
obj-$(CONFIG_CGROUP_DEBUG) += debug.o
diff --git a/kernel/cgroup/cpuset-internal.h b/kernel/cgroup/cpuset-internal.h
index a6c71c86e58d..7ec702dff877 100644
--- a/kernel/cgroup/cpuset-internal.h
+++ b/kernel/cgroup/cpuset-internal.h
@@ -279,6 +279,7 @@ int cpuset_common_seq_show(struct seq_file *sf, void *v);
/*
* cpuset-v1.c
*/
+#ifdef CONFIG_CPUSETS_V1
extern struct cftype legacy_files[];
void fmeter_init(struct fmeter *fmp);
void cpuset_update_task_spread_flags(struct cpuset *cs,
@@ -289,4 +290,16 @@ void hotplug_update_tasks_legacy(struct cpuset *cs,
bool cpus_updated, bool mems_updated);
int validate_change_legacy(struct cpuset *cur, struct cpuset *trial);

+#else
+static inline void fmeter_init(struct fmeter *fmp) {}
+static inline void cpuset_update_task_spread_flags(struct cpuset *cs,
+ struct task_struct *tsk) {}
+static inline void update_tasks_flags(struct cpuset *cs) {}
+static inline void hotplug_update_tasks_legacy(struct cpuset *cs,
+ struct cpumask *new_cpus, nodemask_t *new_mems,
+ bool cpus_updated, bool mems_updated) {}
+static inline int validate_change_legacy(struct cpuset *cur,
+ struct cpuset *trial) { return 0; }
+
+#endif /* CONFIG_CPUSETS_V1 */
#endif /* __CPUSET_INTERNAL_H */
diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
index 2f52fe488f3a..2cefeaaff742 100644
--- a/kernel/cgroup/cpuset.c
+++ b/kernel/cgroup/cpuset.c
@@ -3617,7 +3617,9 @@ struct cgroup_subsys cpuset_cgrp_subsys = {
.can_fork = cpuset_can_fork,
.cancel_fork = cpuset_cancel_fork,
.fork = cpuset_fork,
+#ifdef CONFIG_CPUSETS_V1
.legacy_cftypes = legacy_files,
+#endif
.dfl_cftypes = dfl_files,
.early_init = true,
.threaded = true,
--
2.34.1