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* [PATCH 02/17] sched_ext: Rename ops_cpu_valid() to scx_cpu_valid() and expose it
@ 2026-04-24  1:32 Tejun Heo
  0 siblings, 0 replies; 3+ messages in thread
From: Tejun Heo @ 2026-04-24  1:32 UTC (permalink / raw)
  To: David Vernet, Andrea Righi, Changwoo Min
  Cc: sched-ext, emil, linux-kernel, Cheng-Yang Chou, Zhao Mengmeng,
	Tejun Heo

Rename the static ext.c helper and declare it in ext_internal.h so
ext_idle.c and the upcoming cid code can call it directly instead of
relying on build_policy.c textual inclusion.

Pure rename and visibility change.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Cheng-Yang Chou <yphbchou0911@gmail.com>
---
 kernel/sched/ext.c          | 22 +++++++++++-----------
 kernel/sched/ext_idle.c     |  6 +++---
 kernel/sched/ext_internal.h |  2 ++
 3 files changed, 16 insertions(+), 14 deletions(-)

diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c
index 0ba12449f0c6..1d6613dc4d3b 100644
--- a/kernel/sched/ext.c
+++ b/kernel/sched/ext.c
@@ -1055,7 +1055,7 @@ static inline bool __cpu_valid(s32 cpu)
 }
 
 /**
- * ops_cpu_valid - Verify a cpu number, to be used on ops input args
+ * scx_cpu_valid - Verify a cpu number, to be used on ops input args
  * @sch: scx_sched to abort on error
  * @cpu: cpu number which came from a BPF ops
  * @where: extra information reported on error
@@ -1064,7 +1064,7 @@ static inline bool __cpu_valid(s32 cpu)
  * Verify that it is in range and one of the possible cpus. If invalid, trigger
  * an ops error.
  */
-static bool ops_cpu_valid(struct scx_sched *sch, s32 cpu, const char *where)
+bool scx_cpu_valid(struct scx_sched *sch, s32 cpu, const char *where)
 {
 	if (__cpu_valid(cpu)) {
 		return true;
@@ -1677,7 +1677,7 @@ static struct scx_dispatch_q *find_dsq_for_dispatch(struct scx_sched *sch,
 	if ((dsq_id & SCX_DSQ_LOCAL_ON) == SCX_DSQ_LOCAL_ON) {
 		s32 cpu = dsq_id & SCX_DSQ_LOCAL_CPU_MASK;
 
-		if (!ops_cpu_valid(sch, cpu, "in SCX_DSQ_LOCAL_ON dispatch verdict"))
+		if (!scx_cpu_valid(sch, cpu, "in SCX_DSQ_LOCAL_ON dispatch verdict"))
 			return find_global_dsq(sch, tcpu);
 
 		return &cpu_rq(cpu)->scx.local_dsq;
@@ -3260,7 +3260,7 @@ static int select_task_rq_scx(struct task_struct *p, int prev_cpu, int wake_flag
 		this_rq()->scx.in_select_cpu = false;
 		p->scx.selected_cpu = cpu;
 		*ddsp_taskp = NULL;
-		if (ops_cpu_valid(sch, cpu, "from ops.select_cpu()"))
+		if (scx_cpu_valid(sch, cpu, "from ops.select_cpu()"))
 			return cpu;
 		else
 			return prev_cpu;
@@ -8679,7 +8679,7 @@ static void scx_kick_cpu(struct scx_sched *sch, s32 cpu, u64 flags)
 	struct rq *this_rq;
 	unsigned long irq_flags;
 
-	if (!ops_cpu_valid(sch, cpu, NULL))
+	if (!scx_cpu_valid(sch, cpu, NULL))
 		return;
 
 	local_irq_save(irq_flags);
@@ -8775,7 +8775,7 @@ __bpf_kfunc s32 scx_bpf_dsq_nr_queued(u64 dsq_id)
 	} else if ((dsq_id & SCX_DSQ_LOCAL_ON) == SCX_DSQ_LOCAL_ON) {
 		s32 cpu = dsq_id & SCX_DSQ_LOCAL_CPU_MASK;
 
-		if (ops_cpu_valid(sch, cpu, NULL)) {
+		if (scx_cpu_valid(sch, cpu, NULL)) {
 			ret = READ_ONCE(cpu_rq(cpu)->scx.local_dsq.nr);
 			goto out;
 		}
@@ -9164,7 +9164,7 @@ __bpf_kfunc u32 scx_bpf_cpuperf_cap(s32 cpu, const struct bpf_prog_aux *aux)
 	guard(rcu)();
 
 	sch = scx_prog_sched(aux);
-	if (likely(sch) && ops_cpu_valid(sch, cpu, NULL))
+	if (likely(sch) && scx_cpu_valid(sch, cpu, NULL))
 		return arch_scale_cpu_capacity(cpu);
 	else
 		return SCX_CPUPERF_ONE;
@@ -9192,7 +9192,7 @@ __bpf_kfunc u32 scx_bpf_cpuperf_cur(s32 cpu, const struct bpf_prog_aux *aux)
 	guard(rcu)();
 
 	sch = scx_prog_sched(aux);
-	if (likely(sch) && ops_cpu_valid(sch, cpu, NULL))
+	if (likely(sch) && scx_cpu_valid(sch, cpu, NULL))
 		return arch_scale_freq_capacity(cpu);
 	else
 		return SCX_CPUPERF_ONE;
@@ -9228,7 +9228,7 @@ __bpf_kfunc void scx_bpf_cpuperf_set(s32 cpu, u32 perf, const struct bpf_prog_au
 		return;
 	}
 
-	if (ops_cpu_valid(sch, cpu, NULL)) {
+	if (scx_cpu_valid(sch, cpu, NULL)) {
 		struct rq *rq = cpu_rq(cpu), *locked_rq = scx_locked_rq();
 		struct rq_flags rf;
 
@@ -9341,7 +9341,7 @@ __bpf_kfunc struct rq *scx_bpf_cpu_rq(s32 cpu, const struct bpf_prog_aux *aux)
 	if (unlikely(!sch))
 		return NULL;
 
-	if (!ops_cpu_valid(sch, cpu, NULL))
+	if (!scx_cpu_valid(sch, cpu, NULL))
 		return NULL;
 
 	if (!sch->warned_deprecated_rq) {
@@ -9398,7 +9398,7 @@ __bpf_kfunc struct task_struct *scx_bpf_cpu_curr(s32 cpu, const struct bpf_prog_
 	if (unlikely(!sch))
 		return NULL;
 
-	if (!ops_cpu_valid(sch, cpu, NULL))
+	if (!scx_cpu_valid(sch, cpu, NULL))
 		return NULL;
 
 	return rcu_dereference(cpu_rq(cpu)->curr);
diff --git a/kernel/sched/ext_idle.c b/kernel/sched/ext_idle.c
index c43d62d90e40..11d11ea6ca6b 100644
--- a/kernel/sched/ext_idle.c
+++ b/kernel/sched/ext_idle.c
@@ -917,7 +917,7 @@ static s32 select_cpu_from_kfunc(struct scx_sched *sch, struct task_struct *p,
 	bool we_locked = false;
 	s32 cpu;
 
-	if (!ops_cpu_valid(sch, prev_cpu, NULL))
+	if (!scx_cpu_valid(sch, prev_cpu, NULL))
 		return -EINVAL;
 
 	if (!check_builtin_idle_enabled(sch))
@@ -975,7 +975,7 @@ __bpf_kfunc s32 scx_bpf_cpu_node(s32 cpu, const struct bpf_prog_aux *aux)
 	guard(rcu)();
 
 	sch = scx_prog_sched(aux);
-	if (unlikely(!sch) || !ops_cpu_valid(sch, cpu, NULL))
+	if (unlikely(!sch) || !scx_cpu_valid(sch, cpu, NULL))
 		return NUMA_NO_NODE;
 	return cpu_to_node(cpu);
 }
@@ -1257,7 +1257,7 @@ __bpf_kfunc bool scx_bpf_test_and_clear_cpu_idle(s32 cpu, const struct bpf_prog_
 	if (!check_builtin_idle_enabled(sch))
 		return false;
 
-	if (!ops_cpu_valid(sch, cpu, NULL))
+	if (!scx_cpu_valid(sch, cpu, NULL))
 		return false;
 
 	return scx_idle_test_and_clear_cpu(cpu);
diff --git a/kernel/sched/ext_internal.h b/kernel/sched/ext_internal.h
index c35098668fb1..5e3b79963d41 100644
--- a/kernel/sched/ext_internal.h
+++ b/kernel/sched/ext_internal.h
@@ -1350,6 +1350,8 @@ DECLARE_PER_CPU(struct rq *, scx_locked_rq_state);
 
 int scx_kfunc_context_filter(const struct bpf_prog *prog, u32 kfunc_id);
 
+bool scx_cpu_valid(struct scx_sched *sch, s32 cpu, const char *where);
+
 /*
  * Return the rq currently locked from an scx callback, or NULL if no rq is
  * locked.
-- 
2.53.0


^ permalink raw reply related	[flat|nested] 3+ messages in thread
* [PATCHSET v2 REPOST sched_ext/for-7.2] sched_ext: Topological CPU IDs and cid-form struct_ops
@ 2026-04-24 17:27 Tejun Heo
  2026-04-24 17:27 ` [PATCH 02/17] sched_ext: Rename ops_cpu_valid() to scx_cpu_valid() and expose it Tejun Heo
  0 siblings, 1 reply; 3+ messages in thread
From: Tejun Heo @ 2026-04-24 17:27 UTC (permalink / raw)
  To: David Vernet, Andrea Righi, Changwoo Min
  Cc: sched-ext, emil, linux-kernel, Cheng-Yang Chou, Zhao Mengmeng,
	Tejun Heo

Hello,

Reposting v2 because the original send was not properly threaded -
each patch went out as a standalone top-level message. Content is
unchanged from the original v2.

Original v2: https://lore.kernel.org/r/20260424013220.2923402-1-tj@kernel.org

v2 of https://lore.kernel.org/r/20260421071945.3110084-1-tj@kernel.org

v2:
- Add ext-types.h first patch for early subsystem-wide type defs.
- cid: publish the cid tables with WRITE_ONCE / read with READ_ONCE;
  document the visibility contract.
- cid-kfuncs: NULL-guard scx_bpf_this_cid / scx_bpf_task_cid for
  TRACING/SYSCALL callers before any SCX sched has enabled.
- cid-struct-ops: use struct_size() for the set_cmask_scratch percpu
  alloc; cluster __scx_is_cid_type disable with __scx_enabled disable
  in scx_root_disable().
- cid-kfunc-filter: sync per-entry kfunc flags with each kfunc's
  primary BTF_ID_FLAGS() declaration (Zhao). pahole intersects flags
  across occurrences; omitting them drops the flags globally - the
  visible symptom was KF_IMPLICIT_ARGS getting cleared on
  scx_bpf_kick_cpu, leaking bpf_prog_aux into vmlinux.h.
- cmask: narrow to the helpers this series actually uses;
  cmask_copy_from_kernel contract and runtime guard.

This patchset introduces topological CPU IDs (cids) - dense,
topology-ordered cpu identifiers - and an alternative cid-form struct_ops
type that lets BPF schedulers operate in cid space directly.

Key pieces:

- cid space: scx_cid_init() walks nodes * LLCs * cores * threads and packs
  a dense cid mapping. The mapping can be overridden via
  scx_bpf_cid_override(). See "Topological CPU IDs" in ext_cid.h for the
  model.

- cmask: a base-windowed bitmap over cid space. Kernel and BPF helpers with
  identical semantics. Used by scx_qmap for per-task affinity and idle-cid
  tracking; meant to be the substrate for sub-sched cid allocation.

- bpf_sched_ext_ops_cid: a parallel struct_ops type whose callbacks take
  cids/cmasks instead of cpus/cpumasks. Kernel translates at the boundary
  via scx_cpu_arg() / scx_cpu_ret(); the two struct types share offsets up
  through @priv (verified by BUILD_BUG_ON) so the union view in scx_sched
  works without function-pointer casts. Sub-sched support is tied to
  cid-form: validate_ops() rejects cpu-form sub-scheds and cpu-form roots
  that expose sub_attach / sub_detach.

- cid-form kfuncs: scx_bpf_kick_cid, scx_bpf_cidperf_{cap,cur,set},
  scx_bpf_cid_curr, scx_bpf_task_cid, scx_bpf_this_cid,
  scx_bpf_nr_{cids,online_cids}, scx_bpf_cid_to_cpu, scx_bpf_cpu_to_cid.
  A cid-form program may not call cpu-only kfuncs (enforced at verifier
  load via scx_kfunc_context_filter); the reverse is intentionally
  permissive to ease migration.

- scx_qmap port: scx_qmap is converted to cid-form. It uses the cmask-based
  idle picker, per-task cid-space cpus_allowed, and cid-form kfuncs
  throughout. Sub-sched dispatching via scx_bpf_sub_dispatch() continues to
  work.

v2 re-tested on the 16-cpu QEMU: cid-form scx_qmap, cpu-form scx_simple,
cid<->cpu cycling, scx_qmap under stress-ng, hotplug auto-restart, and
sub-sched (root scx_qmap + cgroup-scoped scx_qmap child). Clean.

Based on sched_ext/for-7.2 (c2929bc21dce).

 0001-sched_ext-Add-ext_types.h-for-early-subsystem-wide-d.patch
 0002-sched_ext-Rename-ops_cpu_valid-to-scx_cpu_valid-and-.patch
 0003-sched_ext-Move-scx_exit-scx_error-and-friends-to-ext.patch
 0004-sched_ext-Shift-scx_kick_cpu-validity-check-to-scx_b.patch
 0005-sched_ext-Relocate-cpu_acquire-cpu_release-to-end-of.patch
 0006-sched_ext-Make-scx_enable-take-scx_enable_cmd.patch
 0007-sched_ext-Add-topological-CPU-IDs-cids.patch
 0008-sched_ext-Add-scx_bpf_cid_override-kfunc.patch
 0009-tools-sched_ext-Add-struct_size-helpers-to-common.bp.patch
 0010-sched_ext-Add-cmask-a-base-windowed-bitmap-over-cid-.patch
 0011-sched_ext-Add-cid-form-kfunc-wrappers-alongside-cpu-.patch
 0012-sched_ext-Add-bpf_sched_ext_ops_cid-struct_ops-type.patch
 0013-sched_ext-Forbid-cpu-form-kfuncs-from-cid-form-sched.patch
 0014-tools-sched_ext-scx_qmap-Restart-on-hotplug-instead-.patch
 0015-tools-sched_ext-scx_qmap-Add-cmask-based-idle-tracki.patch
 0016-tools-sched_ext-scx_qmap-Port-to-cid-form-struct_ops.patch
 0017-sched_ext-Require-cid-form-struct_ops-for-sub-sched-.patch

Git tree: git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext.git scx-cid-v2

 kernel/sched/build_policy.c              |   2 +
 kernel/sched/ext.c                       | 650 +++++++++++++++++++++++++----
 kernel/sched/ext_cid.c                   | 417 ++++++++++++++++++++
 kernel/sched/ext_cid.h                   | 164 ++++++++
 kernel/sched/ext_idle.c                  |   8 +-
 kernel/sched/ext_internal.h              | 203 +++++++---
 kernel/sched/ext_types.h                 | 104 +++++
 tools/sched_ext/include/scx/cid.bpf.h    | 597 ++++++++++++++++++++++++++++
 tools/sched_ext/include/scx/common.bpf.h |  23 ++
 tools/sched_ext/include/scx/compat.bpf.h |  24 ++
 tools/sched_ext/scx_qmap.bpf.c           | 306 ++++++++-------
 tools/sched_ext/scx_qmap.c               |  25 +-
 tools/sched_ext/scx_qmap.h               |   2 +-
 13 files changed, 2240 insertions(+), 285 deletions(-)

--
tejun

^ permalink raw reply	[flat|nested] 3+ messages in thread
* [PATCHSET v3 sched_ext/for-7.2] sched_ext: Topological CPU IDs and cid-form struct_ops
@ 2026-04-28 20:35 Tejun Heo
  2026-04-28 20:35 ` [PATCH 02/17] sched_ext: Rename ops_cpu_valid() to scx_cpu_valid() and expose it Tejun Heo
  0 siblings, 1 reply; 3+ messages in thread
From: Tejun Heo @ 2026-04-28 20:35 UTC (permalink / raw)
  To: David Vernet, Andrea Righi, Changwoo Min
  Cc: sched-ext, Emil Tsalapatis, linux-kernel, Tejun Heo

Hello,

v3 (all from the Sashiko AI review at
https://sashiko.dev/#/patchset/20260424172721.3458520-1-tj%40kernel.org):

- cid: drop leaked cpus_read_lock() on scx_cid_init() failure;
  BUILD_BUG_ON tightened to NR_CPUS<=8192 to match the BPF cmask
  helpers' CMASK_MAX_WORDS coverage.
- bpf-struct-size: use offsetof() in struct_size() to match the
  kernel <linux/overflow.h> macro semantics (no inflation from
  trailing struct padding).
- cmask: cmask_copy_from_kernel() validates src->base==0 via
  probe-read; nr_bits check is bit-level rather than rounded-up
  word-count.
- cid-qmap-idle: qmap_init() refuses to load when scx_bpf_nr_cids()
  exceeds SCX_QMAP_MAX_CPUS; the task_ctx flex array would otherwise
  overflow into the next slab entry.

v2: https://lore.kernel.org/r/20260424172721.3458520-1-tj@kernel.org
v1: https://lore.kernel.org/r/20260421071945.3110084-1-tj@kernel.org

This patchset introduces topological CPU IDs (cids) - dense,
topology-ordered cpu identifiers - and an alternative cid-form struct_ops
type that lets BPF schedulers operate in cid space directly.

Key pieces:

- cid space: scx_cid_init() walks nodes * LLCs * cores * threads and packs
  a dense cid mapping. The mapping can be overridden via
  scx_bpf_cid_override(). See "Topological CPU IDs" in ext_cid.h for the
  model.

- cmask: a base-windowed bitmap over cid space. Kernel and BPF helpers with
  identical semantics. Used by scx_qmap for per-task affinity and idle-cid
  tracking; meant to be the substrate for sub-sched cid allocation.

- bpf_sched_ext_ops_cid: a parallel struct_ops type whose callbacks take
  cids/cmasks instead of cpus/cpumasks. Kernel translates at the boundary
  via scx_cpu_arg() / scx_cpu_ret(); the two struct types share offsets up
  through @priv (verified by BUILD_BUG_ON) so the union view in scx_sched
  works without function-pointer casts. Sub-sched support is tied to
  cid-form: validate_ops() rejects cpu-form sub-scheds and cpu-form roots
  that expose sub_attach / sub_detach.

- cid-form kfuncs: scx_bpf_kick_cid, scx_bpf_cidperf_{cap,cur,set},
  scx_bpf_cid_curr, scx_bpf_task_cid, scx_bpf_this_cid,
  scx_bpf_nr_{cids,online_cids}, scx_bpf_cid_to_cpu, scx_bpf_cpu_to_cid.
  A cid-form program may not call cpu-only kfuncs (enforced at verifier
  load via scx_kfunc_context_filter); the reverse is intentionally
  permissive to ease migration.

- scx_qmap port: scx_qmap is converted to cid-form. It uses the cmask-based
  idle picker, per-task cid-space cpus_allowed, and cid-form kfuncs
  throughout. Sub-sched dispatching via scx_bpf_sub_dispatch() continues to
  work.

v3 re-tested on the 16-cpu QEMU: cid-form scx_qmap under stress-ng plus
reload cycles, hotplug auto-restart, and sub-sched (root scx_qmap +
cgroup-scoped scx_qmap child). Clean.

Based on sched_ext/for-7.2 (4939721aad2e).

 0001-sched_ext-Add-ext_types.h-for-early-subsystem-wide-d.patch
 0002-sched_ext-Rename-ops_cpu_valid-to-scx_cpu_valid-and-.patch
 0003-sched_ext-Move-scx_exit-scx_error-and-friends-to-ext.patch
 0004-sched_ext-Shift-scx_kick_cpu-validity-check-to-scx_b.patch
 0005-sched_ext-Relocate-cpu_acquire-cpu_release-to-end-of.patch
 0006-sched_ext-Make-scx_enable-take-scx_enable_cmd.patch
 0007-sched_ext-Add-topological-CPU-IDs-cids.patch
 0008-sched_ext-Add-scx_bpf_cid_override-kfunc.patch
 0009-tools-sched_ext-Add-struct_size-helpers-to-common.bp.patch
 0010-sched_ext-Add-cmask-a-base-windowed-bitmap-over-cid-.patch
 0011-sched_ext-Add-cid-form-kfunc-wrappers-alongside-cpu-.patch
 0012-sched_ext-Add-bpf_sched_ext_ops_cid-struct_ops-type.patch
 0013-sched_ext-Forbid-cpu-form-kfuncs-from-cid-form-sched.patch
 0014-tools-sched_ext-scx_qmap-Restart-on-hotplug-instead-.patch
 0015-tools-sched_ext-scx_qmap-Add-cmask-based-idle-tracki.patch
 0016-tools-sched_ext-scx_qmap-Port-to-cid-form-struct_ops.patch
 0017-sched_ext-Require-cid-form-struct_ops-for-sub-sched-.patch

Git tree: git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext.git scx-cid-v3

 kernel/sched/build_policy.c              |   3 +
 kernel/sched/ext.c                       | 651 ++++++++++++++++++++++++++----
 kernel/sched/ext_cid.c                   | 409 +++++++++++++++++++
 kernel/sched/ext_cid.h                   | 164 ++++++++
 kernel/sched/ext_idle.c                  |   8 +-
 kernel/sched/ext_internal.h              | 205 +++++++---
 kernel/sched/ext_types.h                 | 104 +++++
 tools/sched_ext/include/scx/cid.bpf.h    | 667 +++++++++++++++++++++++++++++++
 tools/sched_ext/include/scx/common.bpf.h |  23 ++
 tools/sched_ext/include/scx/compat.bpf.h |  24 ++
 tools/sched_ext/scx_qmap.bpf.c           | 346 +++++++++-------
 tools/sched_ext/scx_qmap.c               |  70 +++-
 tools/sched_ext/scx_qmap.h               |   2 +-
 13 files changed, 2391 insertions(+), 285 deletions(-)

Thanks.

--
tejun

^ permalink raw reply	[flat|nested] 3+ messages in thread
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2026-04-24 17:27 [PATCHSET v2 REPOST sched_ext/for-7.2] sched_ext: Topological CPU IDs and cid-form struct_ops Tejun Heo
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2026-04-28 20:35 [PATCHSET v3 sched_ext/for-7.2] sched_ext: Topological CPU IDs and cid-form struct_ops Tejun Heo
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