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From: Ankur Arora <ankur.a.arora@oracle.com>
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        Ankur Arora <ankur.a.arora@oracle.com>
Subject: [PATCH 10/30] sched: separate PREEMPT_DYNAMIC config logic
Date: Mon, 12 Feb 2024 21:55:34 -0800
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Pull out the PREEMPT_DYNAMIC setup logic to allow other preemption
models to dynamically configure preemption.

Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Ankur Arora <ankur.a.arora@oracle.com>
---
 kernel/sched/core.c | 165 +++++++++++++++++++++++---------------------
 1 file changed, 86 insertions(+), 79 deletions(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 8e492d20021c..6c5de6c1da27 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -8692,6 +8692,89 @@ int __cond_resched_rwlock_write(rwlock_t *lock)
 }
 EXPORT_SYMBOL(__cond_resched_rwlock_write);
 
+#if defined(CONFIG_PREEMPT_DYNAMIC)
+
+#define PREEMPT_MODE "Dynamic Preempt"
+
+enum {
+	preempt_dynamic_undefined = -1,
+	preempt_dynamic_none,
+	preempt_dynamic_voluntary,
+	preempt_dynamic_full,
+};
+
+int preempt_dynamic_mode = preempt_dynamic_undefined;
+static DEFINE_MUTEX(sched_dynamic_mutex);
+
+int sched_dynamic_mode(const char *str)
+{
+	if (!strcmp(str, "none"))
+		return preempt_dynamic_none;
+
+	if (!strcmp(str, "voluntary"))
+		return preempt_dynamic_voluntary;
+
+	if (!strcmp(str, "full"))
+		return preempt_dynamic_full;
+
+	return -EINVAL;
+}
+
+static void __sched_dynamic_update(int mode);
+void sched_dynamic_update(int mode)
+{
+	mutex_lock(&sched_dynamic_mutex);
+	__sched_dynamic_update(mode);
+	mutex_unlock(&sched_dynamic_mutex);
+}
+
+static void __init preempt_dynamic_init(void)
+{
+	if (preempt_dynamic_mode == preempt_dynamic_undefined) {
+		if (IS_ENABLED(CONFIG_PREEMPT_NONE)) {
+			sched_dynamic_update(preempt_dynamic_none);
+		} else if (IS_ENABLED(CONFIG_PREEMPT_VOLUNTARY)) {
+			sched_dynamic_update(preempt_dynamic_voluntary);
+		} else {
+			/* Default static call setting, nothing to do */
+			WARN_ON_ONCE(!IS_ENABLED(CONFIG_PREEMPT));
+			preempt_dynamic_mode = preempt_dynamic_full;
+			pr_info("%s: full\n", PREEMPT_MODE);
+		}
+	}
+}
+
+static int __init setup_preempt_mode(char *str)
+{
+	int mode = sched_dynamic_mode(str);
+	if (mode < 0) {
+		pr_warn("%s: unsupported mode: %s\n", PREEMPT_MODE, str);
+		return 0;
+	}
+
+	sched_dynamic_update(mode);
+	return 1;
+}
+__setup("preempt=", setup_preempt_mode);
+
+#define PREEMPT_MODEL_ACCESSOR(mode) \
+	bool preempt_model_##mode(void)						 \
+	{									 \
+		WARN_ON_ONCE(preempt_dynamic_mode == preempt_dynamic_undefined); \
+		return preempt_dynamic_mode == preempt_dynamic_##mode;		 \
+	}									 \
+	EXPORT_SYMBOL_GPL(preempt_model_##mode)
+
+PREEMPT_MODEL_ACCESSOR(none);
+PREEMPT_MODEL_ACCESSOR(voluntary);
+PREEMPT_MODEL_ACCESSOR(full);
+
+#else /* !CONFIG_PREEMPT_DYNAMIC */
+
+static inline void preempt_dynamic_init(void) { }
+
+#endif /* !CONFIG_PREEMPT_DYNAMIC */
+
 #ifdef CONFIG_PREEMPT_DYNAMIC
 
 #ifdef CONFIG_GENERIC_ENTRY
@@ -8728,29 +8811,6 @@ EXPORT_SYMBOL(__cond_resched_rwlock_write);
  *   irqentry_exit_cond_resched <- irqentry_exit_cond_resched
  */
 
-enum {
-	preempt_dynamic_undefined = -1,
-	preempt_dynamic_none,
-	preempt_dynamic_voluntary,
-	preempt_dynamic_full,
-};
-
-int preempt_dynamic_mode = preempt_dynamic_undefined;
-
-int sched_dynamic_mode(const char *str)
-{
-	if (!strcmp(str, "none"))
-		return preempt_dynamic_none;
-
-	if (!strcmp(str, "voluntary"))
-		return preempt_dynamic_voluntary;
-
-	if (!strcmp(str, "full"))
-		return preempt_dynamic_full;
-
-	return -EINVAL;
-}
-
 #if defined(CONFIG_HAVE_PREEMPT_DYNAMIC_CALL)
 #define preempt_dynamic_enable(f)	static_call_update(f, f##_dynamic_enabled)
 #define preempt_dynamic_disable(f)	static_call_update(f, f##_dynamic_disabled)
@@ -8761,7 +8821,6 @@ int sched_dynamic_mode(const char *str)
 #error "Unsupported PREEMPT_DYNAMIC mechanism"
 #endif
 
-static DEFINE_MUTEX(sched_dynamic_mutex);
 static bool klp_override;
 
 static void __sched_dynamic_update(int mode)
@@ -8786,7 +8845,7 @@ static void __sched_dynamic_update(int mode)
 		preempt_dynamic_disable(preempt_schedule_notrace);
 		preempt_dynamic_disable(irqentry_exit_cond_resched);
 		if (mode != preempt_dynamic_mode)
-			pr_info("Dynamic Preempt: none\n");
+			pr_info("%s: none\n", PREEMPT_MODE);
 		break;
 
 	case preempt_dynamic_voluntary:
@@ -8797,7 +8856,7 @@ static void __sched_dynamic_update(int mode)
 		preempt_dynamic_disable(preempt_schedule_notrace);
 		preempt_dynamic_disable(irqentry_exit_cond_resched);
 		if (mode != preempt_dynamic_mode)
-			pr_info("Dynamic Preempt: voluntary\n");
+			pr_info("%s: voluntary\n", PREEMPT_MODE);
 		break;
 
 	case preempt_dynamic_full:
@@ -8808,20 +8867,13 @@ static void __sched_dynamic_update(int mode)
 		preempt_dynamic_enable(preempt_schedule_notrace);
 		preempt_dynamic_enable(irqentry_exit_cond_resched);
 		if (mode != preempt_dynamic_mode)
-			pr_info("Dynamic Preempt: full\n");
+			pr_info("%s: full\n", PREEMPT_MODE);
 		break;
 	}
 
 	preempt_dynamic_mode = mode;
 }
 
-void sched_dynamic_update(int mode)
-{
-	mutex_lock(&sched_dynamic_mutex);
-	__sched_dynamic_update(mode);
-	mutex_unlock(&sched_dynamic_mutex);
-}
-
 #ifdef CONFIG_HAVE_PREEMPT_DYNAMIC_CALL
 
 static int klp_cond_resched(void)
@@ -8852,51 +8904,6 @@ void sched_dynamic_klp_disable(void)
 
 #endif /* CONFIG_HAVE_PREEMPT_DYNAMIC_CALL */
 
-static int __init setup_preempt_mode(char *str)
-{
-	int mode = sched_dynamic_mode(str);
-	if (mode < 0) {
-		pr_warn("Dynamic Preempt: unsupported mode: %s\n", str);
-		return 0;
-	}
-
-	sched_dynamic_update(mode);
-	return 1;
-}
-__setup("preempt=", setup_preempt_mode);
-
-static void __init preempt_dynamic_init(void)
-{
-	if (preempt_dynamic_mode == preempt_dynamic_undefined) {
-		if (IS_ENABLED(CONFIG_PREEMPT_NONE)) {
-			sched_dynamic_update(preempt_dynamic_none);
-		} else if (IS_ENABLED(CONFIG_PREEMPT_VOLUNTARY)) {
-			sched_dynamic_update(preempt_dynamic_voluntary);
-		} else {
-			/* Default static call setting, nothing to do */
-			WARN_ON_ONCE(!IS_ENABLED(CONFIG_PREEMPT));
-			preempt_dynamic_mode = preempt_dynamic_full;
-			pr_info("Dynamic Preempt: full\n");
-		}
-	}
-}
-
-#define PREEMPT_MODEL_ACCESSOR(mode) \
-	bool preempt_model_##mode(void)						 \
-	{									 \
-		WARN_ON_ONCE(preempt_dynamic_mode == preempt_dynamic_undefined); \
-		return preempt_dynamic_mode == preempt_dynamic_##mode;		 \
-	}									 \
-	EXPORT_SYMBOL_GPL(preempt_model_##mode)
-
-PREEMPT_MODEL_ACCESSOR(none);
-PREEMPT_MODEL_ACCESSOR(voluntary);
-PREEMPT_MODEL_ACCESSOR(full);
-
-#else /* !CONFIG_PREEMPT_DYNAMIC */
-
-static inline void preempt_dynamic_init(void) { }
-
 #endif /* #ifdef CONFIG_PREEMPT_DYNAMIC */
 
 /**
-- 
2.31.1