[PATCH sysctl-next] sched: Fix build warning without CONFIG_SYSCTL

[PATCH sysctl-next] sched: Fix build warning without CONFIG_SYSCTL

[YueHaibing]

IF CONFIG_SYSCTL is n, build warn:

kernel/sched/core.c:1782:12: warning: ‘sysctl_sched_uclamp_handler’ defined but not used [-Wunused-function]
 static int sysctl_sched_uclamp_handler(struct ctl_table *table, int write,
            ^~~~~~~~~~~~~~~~~~~~~~~~~~~

sysctl_sched_uclamp_handler() is used while CONFIG_SYSCTL enabled,
wrap all related code with CONFIG_SYSCTL to fix this.

Fixes: 3267e0156c33 ("sched: Move uclamp_util sysctls to core.c")
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
---
 kernel/sched/core.c | 65 +++++++++++++++++++++++++--------------------
 1 file changed, 36 insertions(+), 29 deletions(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index ef31751c5799..b8d2ff09b853 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -1306,10 +1306,10 @@ static void set_load_weight(struct task_struct *p, bool update_load)
 static DEFINE_MUTEX(uclamp_mutex);
 
 /* Max allowed minimum utilization */
-static unsigned int sysctl_sched_uclamp_util_min = SCHED_CAPACITY_SCALE;
+static unsigned int __maybe_unused sysctl_sched_uclamp_util_min = SCHED_CAPACITY_SCALE;
 
 /* Max allowed maximum utilization */
-static unsigned int sysctl_sched_uclamp_util_max = SCHED_CAPACITY_SCALE;
+static unsigned int __maybe_unused sysctl_sched_uclamp_util_max = SCHED_CAPACITY_SCALE;
 
 /*
  * By default RT tasks run at the maximum performance point/capacity of the
@@ -1456,33 +1456,6 @@ static void uclamp_update_util_min_rt_default(struct task_struct *p)
 	task_rq_unlock(rq, p, &rf);
 }
 
-static void uclamp_sync_util_min_rt_default(void)
-{
-	struct task_struct *g, *p;
-
-	/*
-	 * copy_process()			sysctl_uclamp
-	 *					  uclamp_min_rt = X;
-	 *   write_lock(&tasklist_lock)		  read_lock(&tasklist_lock)
-	 *   // link thread			  smp_mb__after_spinlock()
-	 *   write_unlock(&tasklist_lock)	  read_unlock(&tasklist_lock);
-	 *   sched_post_fork()			  for_each_process_thread()
-	 *     __uclamp_sync_rt()		    __uclamp_sync_rt()
-	 *
-	 * Ensures that either sched_post_fork() will observe the new
-	 * uclamp_min_rt or for_each_process_thread() will observe the new
-	 * task.
-	 */
-	read_lock(&tasklist_lock);
-	smp_mb__after_spinlock();
-	read_unlock(&tasklist_lock);
-
-	rcu_read_lock();
-	for_each_process_thread(g, p)
-		uclamp_update_util_min_rt_default(p);
-	rcu_read_unlock();
-}
-
 static inline struct uclamp_se
 uclamp_tg_restrict(struct task_struct *p, enum uclamp_id clamp_id)
 {
@@ -1762,6 +1735,11 @@ uclamp_update_active_tasks(struct cgroup_subsys_state *css)
 }
 
 static void cpu_util_update_eff(struct cgroup_subsys_state *css);
+#endif
+
+#ifdef CONFIG_SYSCTL
+#ifdef CONFIG_UCLAMP_TASK
+#ifdef CONFIG_UCLAMP_TASK_GROUP
 static void uclamp_update_root_tg(void)
 {
 	struct task_group *tg = &root_task_group;
@@ -1779,6 +1757,33 @@ static void uclamp_update_root_tg(void)
 static void uclamp_update_root_tg(void) { }
 #endif
 
+static void uclamp_sync_util_min_rt_default(void)
+{
+	struct task_struct *g, *p;
+
+	/*
+	 * copy_process()			sysctl_uclamp
+	 *					  uclamp_min_rt = X;
+	 *   write_lock(&tasklist_lock)		  read_lock(&tasklist_lock)
+	 *   // link thread			  smp_mb__after_spinlock()
+	 *   write_unlock(&tasklist_lock)	  read_unlock(&tasklist_lock);
+	 *   sched_post_fork()			  for_each_process_thread()
+	 *     __uclamp_sync_rt()		    __uclamp_sync_rt()
+	 *
+	 * Ensures that either sched_post_fork() will observe the new
+	 * uclamp_min_rt or for_each_process_thread() will observe the new
+	 * task.
+	 */
+	read_lock(&tasklist_lock);
+	smp_mb__after_spinlock();
+	read_unlock(&tasklist_lock);
+
+	rcu_read_lock();
+	for_each_process_thread(g, p)
+		uclamp_update_util_min_rt_default(p);
+	rcu_read_unlock();
+}
+
 static int sysctl_sched_uclamp_handler(struct ctl_table *table, int write,
 				void *buffer, size_t *lenp, loff_t *ppos)
 {
@@ -1843,6 +1848,8 @@ static int sysctl_sched_uclamp_handler(struct ctl_table *table, int write,
 
 	return result;
 }
+#endif
+#endif
 
 static int uclamp_validate(struct task_struct *p,
 			   const struct sched_attr *attr)
-- 
2.17.1

Re: [PATCH sysctl-next] sched: Fix build warning without CONFIG_SYSCTL

[Luis Chamberlain]

On Wed, Apr 27, 2022 at 09:10:02PM +0800, YueHaibing wrote:
> IF CONFIG_SYSCTL is n, build warn:
> 
> kernel/sched/core.c:1782:12: warning: ‘sysctl_sched_uclamp_handler’ defined but not used [-Wunused-function]
>  static int sysctl_sched_uclamp_handler(struct ctl_table *table, int write,
>             ^~~~~~~~~~~~~~~~~~~~~~~~~~~
> 
> sysctl_sched_uclamp_handler() is used while CONFIG_SYSCTL enabled,
> wrap all related code with CONFIG_SYSCTL to fix this.
> 
> Fixes: 3267e0156c33 ("sched: Move uclamp_util sysctls to core.c")
> Signed-off-by: YueHaibing <yuehaibing@huawei.com>

Thanks! Merged and pushed onto sysctl-testing. If there are no issues
I'll move  it to sysctl-next.  

  Luis