sched, sched_ext: Move some declarations from kernel/sched/ext.h to sched.h

While sched_ext was out of tree, everything sched_ext specific which can be
put in kernel/sched/ext.h was put there to ease forward porting. However,
kernel/sched/sched.h is the better location for some of them. Relocate.

- struct sched_enq_and_set_ctx, sched_deq_and_put_task() and
  sched_enq_and_set_task().

- scx_enabled() and scx_switched_all().

- for_active_class_range() and for_each_active_class(). sched_class
  declarations are moved above the class iterators for this.

No functional changes intended.

Signed-off-by: Tejun Heo <tj@kernel.org>
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: David Vernet <void@manifault.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 59 insertions, 6 deletions

diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index a12ea0281242..04184e87ba7c 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -2438,19 +2438,54 @@ const struct sched_class name##_sched_class \
 extern struct sched_class __sched_class_highest[];
 extern struct sched_class __sched_class_lowest[];
 
+extern const struct sched_class stop_sched_class;
+extern const struct sched_class dl_sched_class;
+extern const struct sched_class rt_sched_class;
+extern const struct sched_class fair_sched_class;
+extern const struct sched_class idle_sched_class;
+
+#ifdef CONFIG_SCHED_CLASS_EXT
+extern const struct sched_class ext_sched_class;
+
+DECLARE_STATIC_KEY_FALSE(__scx_ops_enabled);	/* SCX BPF scheduler loaded */
+DECLARE_STATIC_KEY_FALSE(__scx_switched_all);	/* all fair class tasks on SCX */
+
+#define scx_enabled()		static_branch_unlikely(&__scx_ops_enabled)
+#define scx_switched_all()	static_branch_unlikely(&__scx_switched_all)
+#else /* !CONFIG_SCHED_CLASS_EXT */
+#define scx_enabled()		false
+#define scx_switched_all()	false
+#endif /* !CONFIG_SCHED_CLASS_EXT */
+
+/*
+ * Iterate only active classes. SCX can take over all fair tasks or be
+ * completely disabled. If the former, skip fair. If the latter, skip SCX.
+ */
+static inline const struct sched_class *next_active_class(const struct sched_class *class)
+{
+	class++;
+#ifdef CONFIG_SCHED_CLASS_EXT
+	if (scx_switched_all() && class == &fair_sched_class)
+		class++;
+	if (!scx_enabled() && class == &ext_sched_class)
+		class++;
+#endif
+	return class;
+}
+
 #define for_class_range(class, _from, _to) \
 	for (class = (_from); class < (_to); class++)
 
 #define for_each_class(class) \
 	for_class_range(class, __sched_class_highest, __sched_class_lowest)
 
-#define sched_class_above(_a, _b)	((_a) < (_b))
+#define for_active_class_range(class, _from, _to)				\
+	for (class = (_from); class != (_to); class = next_active_class(class))
 
-extern const struct sched_class stop_sched_class;
-extern const struct sched_class dl_sched_class;
-extern const struct sched_class rt_sched_class;
-extern const struct sched_class fair_sched_class;
-extern const struct sched_class idle_sched_class;
+#define for_each_active_class(class)						\
+	for_active_class_range(class, __sched_class_highest, __sched_class_lowest)
+
+#define sched_class_above(_a, _b)	((_a) < (_b))
 
 static inline bool sched_stop_runnable(struct rq *rq)
 {
@@ -3698,6 +3733,24 @@ static inline void balance_callbacks(struct rq *rq, struct balance_callback *hea
 
 #endif
 
+#ifdef CONFIG_SCHED_CLASS_EXT
+/*
+ * Used by SCX in the enable/disable paths to move tasks between sched_classes
+ * and establish invariants.
+ */
+struct sched_enq_and_set_ctx {
+	struct task_struct	*p;
+	int			queue_flags;
+	bool			queued;
+	bool			running;
+};
+
+void sched_deq_and_put_task(struct task_struct *p, int queue_flags,
+			    struct sched_enq_and_set_ctx *ctx);
+void sched_enq_and_set_task(struct sched_enq_and_set_ctx *ctx);
+
+#endif /* CONFIG_SCHED_CLASS_EXT */
+
 #include "ext.h"
 
 #endif /* _KERNEL_SCHED_SCHED_H */