[PATCH sched_ext/for-7.3] sched_ext: Replace open-coded event lists with SCX_EVENTS_LIST

[PATCH sched_ext/for-7.3] sched_ext: Replace open-coded event lists with SCX_EVENTS_LIST

[Cheng-Yang Chou]

Three sites enumerate every scx_event_stats field by name:
scx_read_events(), scx_attr_events_show(), and scx_dump_state().
Adding a new SCX_EV_* event requires three separate manual edits.
Missing any one silently drops counts or omits the field from
diagnostic output with no compile-time indication.

SCX_EVENTS_LIST(SCX_EVENT) in internal.h becomes the single
authoritative list of event names, with NR_SCX_EVENTS derived
from the struct size, so all three sites stay in sync with one
edit instead of three.

No functional changes.

Signed-off-by: Cheng-Yang Chou <yphbchou0911@gmail.com>
---
 kernel/sched/ext/ext.c      | 64 +++++++------------------------------
 kernel/sched/ext/internal.h | 17 ++++++++++
 2 files changed, 29 insertions(+), 52 deletions(-)

diff --git a/kernel/sched/ext/ext.c b/kernel/sched/ext/ext.c
index 9c9cb9d08bca..57acefdd9573 100644
--- a/kernel/sched/ext/ext.c
+++ b/kernel/sched/ext/ext.c
@@ -1004,16 +1004,6 @@ static struct task_struct *scx_task_iter_next_locked(struct scx_task_iter *iter)
 	trace_sched_ext_event(#name, cnt);					\
 } while(0)
 
-/**
- * scx_agg_event - Aggregate an event counter 'kind' from 'src_e' to 'dst_e'
- * @dst_e: destination event stats
- * @src_e: source event stats
- * @kind: a kind of event to be aggregated
- */
-#define scx_agg_event(dst_e, src_e, kind) do {					\
-	(dst_e)->kind += READ_ONCE((src_e)->kind);				\
-} while(0)
-
 /**
  * scx_dump_event - Dump an event 'kind' in 'events' to 's'
  * @s: output seq_buf
@@ -4989,19 +4979,9 @@ static ssize_t scx_attr_events_show(struct kobject *kobj,
 	int at = 0;
 
 	scx_read_events(sch, &events);
-	at += scx_attr_event_show(buf, at, &events, SCX_EV_SELECT_CPU_FALLBACK);
-	at += scx_attr_event_show(buf, at, &events, SCX_EV_DISPATCH_LOCAL_DSQ_OFFLINE);
-	at += scx_attr_event_show(buf, at, &events, SCX_EV_DISPATCH_KEEP_LAST);
-	at += scx_attr_event_show(buf, at, &events, SCX_EV_ENQ_SKIP_EXITING);
-	at += scx_attr_event_show(buf, at, &events, SCX_EV_ENQ_SKIP_MIGRATION_DISABLED);
-	at += scx_attr_event_show(buf, at, &events, SCX_EV_REENQ_IMMED);
-	at += scx_attr_event_show(buf, at, &events, SCX_EV_REENQ_LOCAL_REPEAT);
-	at += scx_attr_event_show(buf, at, &events, SCX_EV_REFILL_SLICE_DFL);
-	at += scx_attr_event_show(buf, at, &events, SCX_EV_BYPASS_DURATION);
-	at += scx_attr_event_show(buf, at, &events, SCX_EV_BYPASS_DISPATCH);
-	at += scx_attr_event_show(buf, at, &events, SCX_EV_BYPASS_ACTIVATE);
-	at += scx_attr_event_show(buf, at, &events, SCX_EV_INSERT_NOT_OWNED);
-	at += scx_attr_event_show(buf, at, &events, SCX_EV_SUB_BYPASS_DISPATCH);
+#define SCX_EVENT(name)	at += scx_attr_event_show(buf, at, &events, name)
+	SCX_EVENTS_LIST(SCX_EVENT);
+#undef SCX_EVENT
 	return at;
 }
 SCX_ATTR(events);
@@ -6651,19 +6631,9 @@ static void scx_dump_state(struct scx_sched *sch, struct scx_exit_info *ei,
 	dump_line(&s, "--------------");
 
 	scx_read_events(sch, &events);
-	scx_dump_event(s, &events, SCX_EV_SELECT_CPU_FALLBACK);
-	scx_dump_event(s, &events, SCX_EV_DISPATCH_LOCAL_DSQ_OFFLINE);
-	scx_dump_event(s, &events, SCX_EV_DISPATCH_KEEP_LAST);
-	scx_dump_event(s, &events, SCX_EV_ENQ_SKIP_EXITING);
-	scx_dump_event(s, &events, SCX_EV_ENQ_SKIP_MIGRATION_DISABLED);
-	scx_dump_event(s, &events, SCX_EV_REENQ_IMMED);
-	scx_dump_event(s, &events, SCX_EV_REENQ_LOCAL_REPEAT);
-	scx_dump_event(s, &events, SCX_EV_REFILL_SLICE_DFL);
-	scx_dump_event(s, &events, SCX_EV_BYPASS_DURATION);
-	scx_dump_event(s, &events, SCX_EV_BYPASS_DISPATCH);
-	scx_dump_event(s, &events, SCX_EV_BYPASS_ACTIVATE);
-	scx_dump_event(s, &events, SCX_EV_INSERT_NOT_OWNED);
-	scx_dump_event(s, &events, SCX_EV_SUB_BYPASS_DISPATCH);
+#define SCX_EVENT(name)	scx_dump_event(s, &events, name)
+	SCX_EVENTS_LIST(SCX_EVENT);
+#undef SCX_EVENT
 
 	if (seq_buf_has_overflowed(&s) && dump_len >= sizeof(trunc_marker))
 		memcpy(ei->dump + dump_len - sizeof(trunc_marker),
@@ -10333,26 +10303,16 @@ __bpf_kfunc u64 scx_bpf_now(void)
 
 static void scx_read_events(struct scx_sched *sch, struct scx_event_stats *events)
 {
-	struct scx_event_stats *e_cpu;
-	int cpu;
+	int cpu, i;
 
 	/* Aggregate per-CPU event counters into @events. */
 	memset(events, 0, sizeof(*events));
 	for_each_possible_cpu(cpu) {
-		e_cpu = &per_cpu_ptr(sch->pcpu, cpu)->event_stats;
-		scx_agg_event(events, e_cpu, SCX_EV_SELECT_CPU_FALLBACK);
-		scx_agg_event(events, e_cpu, SCX_EV_DISPATCH_LOCAL_DSQ_OFFLINE);
-		scx_agg_event(events, e_cpu, SCX_EV_DISPATCH_KEEP_LAST);
-		scx_agg_event(events, e_cpu, SCX_EV_ENQ_SKIP_EXITING);
-		scx_agg_event(events, e_cpu, SCX_EV_ENQ_SKIP_MIGRATION_DISABLED);
-		scx_agg_event(events, e_cpu, SCX_EV_REENQ_IMMED);
-		scx_agg_event(events, e_cpu, SCX_EV_REENQ_LOCAL_REPEAT);
-		scx_agg_event(events, e_cpu, SCX_EV_REFILL_SLICE_DFL);
-		scx_agg_event(events, e_cpu, SCX_EV_BYPASS_DURATION);
-		scx_agg_event(events, e_cpu, SCX_EV_BYPASS_DISPATCH);
-		scx_agg_event(events, e_cpu, SCX_EV_BYPASS_ACTIVATE);
-		scx_agg_event(events, e_cpu, SCX_EV_INSERT_NOT_OWNED);
-		scx_agg_event(events, e_cpu, SCX_EV_SUB_BYPASS_DISPATCH);
+		const s64 *src = (const s64 *)&per_cpu_ptr(sch->pcpu, cpu)->event_stats;
+		s64 *dst = (s64 *)events;
+
+		for (i = 0; i < NR_SCX_EVENTS; i++)
+			dst[i] += READ_ONCE(src[i]);
 	}
 }
 
diff --git a/kernel/sched/ext/internal.h b/kernel/sched/ext/internal.h
index 75522a5f28f4..b03fdb382af7 100644
--- a/kernel/sched/ext/internal.h
+++ b/kernel/sched/ext/internal.h
@@ -1051,6 +1051,23 @@ struct scx_event_stats {
 	s64		SCX_EV_SUB_BYPASS_DISPATCH;
 };
 
+#define SCX_EVENTS_LIST(SCX_EVENT)					\
+	SCX_EVENT(SCX_EV_SELECT_CPU_FALLBACK);				\
+	SCX_EVENT(SCX_EV_DISPATCH_LOCAL_DSQ_OFFLINE);			\
+	SCX_EVENT(SCX_EV_DISPATCH_KEEP_LAST);				\
+	SCX_EVENT(SCX_EV_ENQ_SKIP_EXITING);				\
+	SCX_EVENT(SCX_EV_ENQ_SKIP_MIGRATION_DISABLED);			\
+	SCX_EVENT(SCX_EV_REENQ_IMMED);					\
+	SCX_EVENT(SCX_EV_REENQ_LOCAL_REPEAT);				\
+	SCX_EVENT(SCX_EV_REFILL_SLICE_DFL);				\
+	SCX_EVENT(SCX_EV_BYPASS_DURATION);				\
+	SCX_EVENT(SCX_EV_BYPASS_DISPATCH);				\
+	SCX_EVENT(SCX_EV_BYPASS_ACTIVATE);				\
+	SCX_EVENT(SCX_EV_INSERT_NOT_OWNED);				\
+	SCX_EVENT(SCX_EV_SUB_BYPASS_DISPATCH)
+
+#define NR_SCX_EVENTS	(sizeof(struct scx_event_stats) / sizeof(s64))
+
 struct scx_sched;
 
 enum scx_sched_pcpu_flags {
-- 
2.43.0

Re: [PATCH sched_ext/for-7.3] sched_ext: Replace open-coded event lists with SCX_EVENTS_LIST

[Tejun Heo]

Hello,

On Mon, Jun 29, 2026 at 10:35:11PM +0800, Cheng-Yang Chou wrote:
> +		const s64 *src = (const s64 *)&per_cpu_ptr(sch->pcpu, cpu)->event_stats;
> +		s64 *dst = (s64 *)events;
> +
> +		for (i = 0; i < NR_SCX_EVENTS; i++)
> +			dst[i] += READ_ONCE(src[i]);

scx_read_events() can expand SCX_EVENTS_LIST() too, like the other two
sites:

	struct scx_event_stats *e_cpu = &per_cpu_ptr(sch->pcpu, cpu)->event_stats;
#define SCX_EVENT(name)	events->name += READ_ONCE(e_cpu->name)
	SCX_EVENTS_LIST(SCX_EVENT);
#undef SCX_EVENT

That keeps all three sites consistent and lets you drop NR_SCX_EVENTS and
the s64 casts, which assume the struct stays a packed array of s64.

Thanks.

--
tejun