scx: Cosmetic changes

- Whitespace and comment adj.

- Use sched_class_above() instead of naked comparison.

- Reorder hotplug functions.

- s/promote_op_nth_arg()/set_arg_maybe_null()/. Relocate @arg_n after @op
  and remove promote_op_arg().

- Reorder declarations and dummy defs in kernel/sched/ext.h.

No functional changes.

kernel/sched/ext.c

@@ -1017,7 +1017,7 @@ static u32 higher_bits(u32 flags)
 static u32 highest_bit(u32 flags)
 {
 	int bit = fls(flags);
-	return ((u64) 1 << bit) >> 1;
+	return ((u64)1 << bit) >> 1;
 }
 
 /*
@@ -1820,8 +1820,8 @@ static void do_enqueue_task(struct rq *rq, struct task_struct *p, u64 enq_flags,
 		goto local_norefill;
 
 	/*
-	 * If !rq->online, we already told the BPF scheduler that the CPU is
-	 * offline. We're just trying to on/offline the CPU. Don't bother the
+	 * If !scx_rq_online(), we already told the BPF scheduler that the CPU
+	 * is offline and are just running the hotplug path. Don't bother the
 	 * BPF scheduler.
 	 */
 	if (!scx_rq_online(rq))
@@ -2402,7 +2402,8 @@ dispatch_to_local_dsq(struct rq *rq, struct rq_flags *rf, u64 dsq_id,
 		}
 
 		/* if the destination CPU is idle, wake it up */
-		if (dsp && p->sched_class < dst_rq->curr->sched_class)
+		if (dsp && sched_class_above(p->sched_class,
+					     dst_rq->curr->sched_class))
 			resched_curr(dst_rq);
 
 		dispatch_to_local_dsq_unlock(rq, rf, src_rq, locked_dst_rq);
@@ -3218,24 +3219,24 @@ static void handle_hotplug(struct rq *rq, bool online)
 			     online ? "online" : "offline");
 }
 
-static void rq_online_scx(struct rq *rq)
+void scx_rq_activate(struct rq *rq)
 {
-	rq->scx.flags |= SCX_RQ_ONLINE;
+	handle_hotplug(rq, true);
 }
 
-static void rq_offline_scx(struct rq *rq)
+void scx_rq_deactivate(struct rq *rq)
 {
-	rq->scx.flags &= ~SCX_RQ_ONLINE;
+	handle_hotplug(rq, false);
 }
 
-void scx_rq_activate(struct rq *rq)
+static void rq_online_scx(struct rq *rq)
 {
-	handle_hotplug(rq, true);
+	rq->scx.flags |= SCX_RQ_ONLINE;
 }
 
-void scx_rq_deactivate(struct rq *rq)
+static void rq_offline_scx(struct rq *rq)
 {
-	handle_hotplug(rq, false);
+	rq->scx.flags &= ~SCX_RQ_ONLINE;
 }
 
 #else	/* CONFIG_SMP */
@@ -5183,8 +5184,7 @@ extern struct btf *btf_vmlinux;
 static const struct btf_type *task_struct_type;
 static u32 task_struct_type_id;
 
-static bool promote_op_nth_arg(int arg_n, const char *op,
-			       int off, int size,
+static bool set_arg_maybe_null(const char *op, int arg_n, int off, int size,
 			       enum bpf_access_type type,
 			       const struct bpf_prog *prog,
 			       struct bpf_insn_access_aux *info)
@@ -5242,23 +5242,15 @@ static bool promote_op_nth_arg(int arg_n, const char *op,
 	return false;
 }
 
-static bool promote_op_arg(int off, int size,
-			   enum bpf_access_type type,
-			   const struct bpf_prog *prog,
-			   struct bpf_insn_access_aux *info)
-{
-	return promote_op_nth_arg(1, "dispatch", off, size, type, prog, info) ||
-	       promote_op_nth_arg(1, "yield", off, size, type, prog, info);
-}
-
 static bool bpf_scx_is_valid_access(int off, int size,
 				    enum bpf_access_type type,
 				    const struct bpf_prog *prog,
 				    struct bpf_insn_access_aux *info)
 {
 	if (type != BPF_READ)
 		return false;
-	if (promote_op_arg(off, size, type, prog, info))
+	if (set_arg_maybe_null("dispatch", 1, off, size, type, prog, info) ||
+	    set_arg_maybe_null("yield", 1, off, size, type, prog, info))
 		return true;
 	if (off < 0 || off >= sizeof(__u64) * MAX_BPF_FUNC_ARGS)
 		return false;

kernel/sched/ext.h

@@ -41,12 +41,12 @@ void scx_pre_fork(struct task_struct *p);
 int scx_fork(struct task_struct *p);
 void scx_post_fork(struct task_struct *p);
 void scx_cancel_fork(struct task_struct *p);
-int scx_check_setscheduler(struct task_struct *p, int policy);
 bool scx_can_stop_tick(struct rq *rq);
-bool task_should_scx(struct task_struct *p);
-void init_sched_ext_class(void);
 void scx_rq_activate(struct rq *rq);
 void scx_rq_deactivate(struct rq *rq);
+int scx_check_setscheduler(struct task_struct *p, int policy);
+bool task_should_scx(struct task_struct *p);
+void init_sched_ext_class(void);
 
 static inline u32 scx_cpuperf_target(s32 cpu)
 {
@@ -97,13 +97,13 @@ static inline void scx_pre_fork(struct task_struct *p) {}
 static inline int scx_fork(struct task_struct *p) { return 0; }
 static inline void scx_post_fork(struct task_struct *p) {}
 static inline void scx_cancel_fork(struct task_struct *p) {}
-static inline int scx_check_setscheduler(struct task_struct *p, int policy) { return 0; }
-static inline bool scx_can_stop_tick(struct rq *rq) { return true; }
-static inline bool task_on_scx(const struct task_struct *p) { return false; }
-static inline void init_sched_ext_class(void) {}
 static inline u32 scx_cpuperf_target(s32 cpu) { return 0; }
+static inline bool scx_can_stop_tick(struct rq *rq) { return true; }
 static inline void scx_rq_activate(struct rq *rq) {}
 static inline void scx_rq_deactivate(struct rq *rq) {}
+static inline int scx_check_setscheduler(struct task_struct *p, int policy) { return 0; }
+static inline bool task_on_scx(const struct task_struct *p) { return false; }
+static inline void init_sched_ext_class(void) {}
 
 #define for_each_active_class		for_each_class
 #define for_balance_class_range		for_class_range