[PATCH 01/17] sched_ext: Add ext_types.h for early subsystem-wide defs

[Tejun Heo <tj@kernel.org>]

Introduce kernel/sched/ext_types.h as the early-def header for the
sched_ext compilation unit. Included from kernel/sched/build_policy.c
before ext_internal.h so every later header and source in the unit
sees its content without re-inclusion. Later patches add their types
here (struct scx_cid_topo, scx_cmask, scx_cid_shard, etc.) so the
subsystem has one place to stash types shared across the TU.

Move enum scx_consts (SCX_DSP_DFL_MAX_BATCH, SCX_WATCHDOG_MAX_TIMEOUT,
SCX_SUB_MAX_DEPTH, etc.) here as the initial content. Ops-facing
content stays in ext_internal.h.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
 kernel/sched/build_policy.c |  1 +
 kernel/sched/ext_internal.h | 32 ---------------------------
 kernel/sched/ext_types.h    | 43 +++++++++++++++++++++++++++++++++++++
 3 files changed, 44 insertions(+), 32 deletions(-)
 create mode 100644 kernel/sched/ext_types.h

diff --git a/kernel/sched/build_policy.c b/kernel/sched/build_policy.c
index 755883faf751..180ade38625e 100644
--- a/kernel/sched/build_policy.c
+++ b/kernel/sched/build_policy.c
@@ -58,6 +58,7 @@
 #include "deadline.c"
 
 #ifdef CONFIG_SCHED_CLASS_EXT
+# include "ext_types.h"
 # include "ext_internal.h"
 # include "ext.c"
 # include "ext_idle.c"
diff --git a/kernel/sched/ext_internal.h b/kernel/sched/ext_internal.h
index 4a7ffc7f55d2..c35098668fb1 100644
--- a/kernel/sched/ext_internal.h
+++ b/kernel/sched/ext_internal.h
@@ -8,38 +8,6 @@
 #define SCX_OP_IDX(op)		(offsetof(struct sched_ext_ops, op) / sizeof(void (*)(void)))
 #define SCX_MOFF_IDX(moff)	((moff) / sizeof(void (*)(void)))
 
-enum scx_consts {
-	SCX_DSP_DFL_MAX_BATCH		= 32,
-	SCX_DSP_MAX_LOOPS		= 32,
-	SCX_WATCHDOG_MAX_TIMEOUT	= 30 * HZ,
-
-	/* per-CPU chunk size for p->scx.tid allocation, see scx_alloc_tid() */
-	SCX_TID_CHUNK			= 1024,
-
-	SCX_EXIT_BT_LEN			= 64,
-	SCX_EXIT_MSG_LEN		= 1024,
-	SCX_EXIT_DUMP_DFL_LEN		= 32768,
-
-	SCX_CPUPERF_ONE			= SCHED_CAPACITY_SCALE,
-
-	/*
-	 * Iterating all tasks may take a while. Periodically drop
-	 * scx_tasks_lock to avoid causing e.g. CSD and RCU stalls.
-	 */
-	SCX_TASK_ITER_BATCH		= 32,
-
-	SCX_BYPASS_HOST_NTH		= 2,
-
-	SCX_BYPASS_LB_DFL_INTV_US	= 500 * USEC_PER_MSEC,
-	SCX_BYPASS_LB_DONOR_PCT		= 125,
-	SCX_BYPASS_LB_MIN_DELTA_DIV	= 4,
-	SCX_BYPASS_LB_BATCH		= 256,
-
-	SCX_REENQ_LOCAL_MAX_REPEAT	= 256,
-
-	SCX_SUB_MAX_DEPTH		= 4,
-};
-
 enum scx_exit_kind {
 	SCX_EXIT_NONE,
 	SCX_EXIT_DONE,
diff --git a/kernel/sched/ext_types.h b/kernel/sched/ext_types.h
new file mode 100644
index 000000000000..19299ec3920e
--- /dev/null
+++ b/kernel/sched/ext_types.h
@@ -0,0 +1,43 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Early sched_ext type definitions.
+ *
+ * Copyright (c) 2026 Meta Platforms, Inc. and affiliates.
+ * Copyright (c) 2026 Tejun Heo <tj@kernel.org>
+ */
+#ifndef _KERNEL_SCHED_EXT_TYPES_H
+#define _KERNEL_SCHED_EXT_TYPES_H
+
+enum scx_consts {
+	SCX_DSP_DFL_MAX_BATCH		= 32,
+	SCX_DSP_MAX_LOOPS		= 32,
+	SCX_WATCHDOG_MAX_TIMEOUT	= 30 * HZ,
+
+	/* per-CPU chunk size for p->scx.tid allocation, see scx_alloc_tid() */
+	SCX_TID_CHUNK			= 1024,
+
+	SCX_EXIT_BT_LEN			= 64,
+	SCX_EXIT_MSG_LEN		= 1024,
+	SCX_EXIT_DUMP_DFL_LEN		= 32768,
+
+	SCX_CPUPERF_ONE			= SCHED_CAPACITY_SCALE,
+
+	/*
+	 * Iterating all tasks may take a while. Periodically drop
+	 * scx_tasks_lock to avoid causing e.g. CSD and RCU stalls.
+	 */
+	SCX_TASK_ITER_BATCH		= 32,
+
+	SCX_BYPASS_HOST_NTH		= 2,
+
+	SCX_BYPASS_LB_DFL_INTV_US	= 500 * USEC_PER_MSEC,
+	SCX_BYPASS_LB_DONOR_PCT		= 125,
+	SCX_BYPASS_LB_MIN_DELTA_DIV	= 4,
+	SCX_BYPASS_LB_BATCH		= 256,
+
+	SCX_REENQ_LOCAL_MAX_REPEAT	= 256,
+
+	SCX_SUB_MAX_DEPTH		= 4,
+};
+
+#endif /* _KERNEL_SCHED_EXT_TYPES_H */
-- 
2.53.0