sched_ext: idle: Make idle static keys private

Make all the static keys used by the idle CPU selection policy private
to ext_idle.c. This avoids unnecessary exposure in headers and improves
code encapsulation.

Cc: Yury Norov <yury.norov@gmail.com>
Signed-off-by: Andrea Righi <arighi@nvidia.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

Author: arighi

kernel/sched/ext.c

@@ -4765,7 +4765,7 @@ static void scx_ops_disable_workfn(struct kthread_work *work)
 	static_branch_disable(&scx_ops_enq_exiting);
 	static_branch_disable(&scx_ops_enq_migration_disabled);
 	static_branch_disable(&scx_ops_cpu_preempt);
-	static_branch_disable(&scx_builtin_idle_enabled);
+	scx_idle_disable();
 	synchronize_rcu();
 
 	if (ei->kind >= SCX_EXIT_ERROR) {
@@ -5403,12 +5403,7 @@ static int scx_ops_enable(struct sched_ext_ops *ops, struct bpf_link *link)
 	if (scx_ops.cpu_acquire || scx_ops.cpu_release)
 		static_branch_enable(&scx_ops_cpu_preempt);
 
-	if (!ops->update_idle || (ops->flags & SCX_OPS_KEEP_BUILTIN_IDLE)) {
-		scx_idle_reset_masks();
-		static_branch_enable(&scx_builtin_idle_enabled);
-	} else {
-		static_branch_disable(&scx_builtin_idle_enabled);
-	}
+	scx_idle_enable(ops);
 
 	/*
 	 * Lock out forks, cgroup on/offlining and moves before opening the

kernel/sched/ext_idle.c

@@ -12,7 +12,7 @@
 #include "ext_idle.h"
 
 /* Enable/disable built-in idle CPU selection policy */
-DEFINE_STATIC_KEY_FALSE(scx_builtin_idle_enabled);
+static DEFINE_STATIC_KEY_FALSE(scx_builtin_idle_enabled);
 
 #ifdef CONFIG_SMP
 #ifdef CONFIG_CPUMASK_OFFSTACK
@@ -22,10 +22,10 @@ DEFINE_STATIC_KEY_FALSE(scx_builtin_idle_enabled);
 #endif
 
 /* Enable/disable LLC aware optimizations */
-DEFINE_STATIC_KEY_FALSE(scx_selcpu_topo_llc);
+static DEFINE_STATIC_KEY_FALSE(scx_selcpu_topo_llc);
 
 /* Enable/disable NUMA aware optimizations */
-DEFINE_STATIC_KEY_FALSE(scx_selcpu_topo_numa);
+static DEFINE_STATIC_KEY_FALSE(scx_selcpu_topo_numa);
 
 static struct {
 	cpumask_var_t cpu;
@@ -441,16 +441,6 @@ s32 scx_select_cpu_dfl(struct task_struct *p, s32 prev_cpu, u64 wake_flags, bool
 	return cpu;
 }
 
-void scx_idle_reset_masks(void)
-{
-	/*
-	 * Consider all online cpus idle. Should converge to the actual state
-	 * quickly.
-	 */
-	cpumask_copy(idle_masks.cpu, cpu_online_mask);
-	cpumask_copy(idle_masks.smt, cpu_online_mask);
-}
-
 void scx_idle_init_masks(void)
 {
 	BUG_ON(!alloc_cpumask_var(&idle_masks.cpu, GFP_KERNEL));
@@ -532,6 +522,29 @@ void __scx_update_idle(struct rq *rq, bool idle, bool do_notify)
 }
 #endif	/* CONFIG_SMP */
 
+void scx_idle_enable(struct sched_ext_ops *ops)
+{
+	if (ops->update_idle && !(ops->flags & SCX_OPS_KEEP_BUILTIN_IDLE)) {
+		static_branch_disable(&scx_builtin_idle_enabled);
+		return;
+	}
+	static_branch_enable(&scx_builtin_idle_enabled);
+
+#ifdef CONFIG_SMP
+	/*
+	 * Consider all online cpus idle. Should converge to the actual state
+	 * quickly.
+	 */
+	cpumask_copy(idle_masks.cpu, cpu_online_mask);
+	cpumask_copy(idle_masks.smt, cpu_online_mask);
+#endif
+}
+
+void scx_idle_disable(void)
+{
+	static_branch_disable(&scx_builtin_idle_enabled);
+}
+
 /********************************************************************************
  * Helpers that can be called from the BPF scheduler.
  */

kernel/sched/ext_idle.h

@@ -10,20 +10,15 @@
 #ifndef _KERNEL_SCHED_EXT_IDLE_H
 #define _KERNEL_SCHED_EXT_IDLE_H
 
-extern struct static_key_false scx_builtin_idle_enabled;
+struct sched_ext_ops;
 
 #ifdef CONFIG_SMP
-extern struct static_key_false scx_selcpu_topo_llc;
-extern struct static_key_false scx_selcpu_topo_numa;
-
 void scx_idle_update_selcpu_topology(void);
-void scx_idle_reset_masks(void);
 void scx_idle_init_masks(void);
 bool scx_idle_test_and_clear_cpu(int cpu);
 s32 scx_pick_idle_cpu(const struct cpumask *cpus_allowed, u64 flags);
 #else /* !CONFIG_SMP */
 static inline void scx_idle_update_selcpu_topology(void) {}
-static inline void scx_idle_reset_masks(void) {}
 static inline void scx_idle_init_masks(void) {}
 static inline bool scx_idle_test_and_clear_cpu(int cpu) { return false; }
 static inline s32 scx_pick_idle_cpu(const struct cpumask *cpus_allowed, u64 flags)
@@ -33,7 +28,8 @@ static inline s32 scx_pick_idle_cpu(const struct cpumask *cpus_allowed, u64 flag
 #endif /* CONFIG_SMP */
 
 s32 scx_select_cpu_dfl(struct task_struct *p, s32 prev_cpu, u64 wake_flags, bool *found);
-
-extern int scx_idle_init(void);
+void scx_idle_enable(struct sched_ext_ops *ops);
+void scx_idle_disable(void);
+int scx_idle_init(void);
 
 #endif /* _KERNEL_SCHED_EXT_IDLE_H */