kernel/linux.git/tools/sched_ext/include, branch v7.2-rc1

sched_ext: Move sources under kernel/sched/ext/

2026-06-22T15:32:56+00:00

The sched_ext sources had grown to ten ext* files directly under kernel/sched/. Move them into a new kernel/sched/ext/ subdirectory and drop the now-redundant ext_ prefix. ext.c/h keep their names. kernel/sched/ext.{c,h} -> kernel/sched/ext/ext.{c,h} kernel/sched/ext_internal.h -> kernel/sched/ext/internal.h kernel/sched/ext_types.h -> kernel/sched/ext/types.h kernel/sched/ext_idle.{c,h} -> kernel/sched/ext/idle.{c,h} kernel/sched/ext_cid.{c,h} -> kernel/sched/ext/cid.{c,h} kernel/sched/ext_arena.{c,h} -> kernel/sched/ext/arena.{c,h} The include paths in build_policy.c and sched.h, the MAINTAINERS glob, and a few documentation and comment references are updated to match. No code or symbol changes. Suggested-by: Linus Torvalds Reviewed-by: Andrea Righi Signed-off-by: Tejun Heo

sched_ext: Make scx_bpf_kick_cid() return s32

2026-06-04T01:46:56+00:00

Switch scx_bpf_kick_cid() from void to s32 so future cap enforcement can surface failures. cid interface is introduced in this cycle and has no external users, so the ABI change is safe. Subsequent patches will add -EPERM returns when the calling sub-sched lacks the required cap on the target cid. v2: Return scx_cid_to_cpu()'s errno instead of -EINVAL. (Andrea) Signed-off-by: Tejun Heo Reviewed-by: Andrea Righi

tools/sched_ext: Order single-cid cmask helpers as (cid, mask)

2026-06-04T01:46:56+00:00

The BPF arena single-cid cmask helpers take the cmask first and the cid second. Reorder them to (cid, mask) to match the kernel-side helpers and the test_bit(nr, addr), cpumask_test_cpu(cpu, mask) convention. Range and iteration helpers keep (mask, start). Signed-off-by: Tejun Heo Reviewed-by: Andrea Righi

sched_ext: Convert ops.set_cmask() to arena-resident cmask

2026-05-25T19:44:07+00:00

ops_cid.set_cmask() expects a cmask. The kernel couldn't write into the arena, so it translated cpumask -> cmask in kernel memory and passed the result as a trusted pointer. The BPF cmask helpers all operate on arena cmasks though, so the BPF side had to word-by-word probe-read the kernel cmask into an arena cmask via cmask_copy_from_kernel() before any helper could touch it. It works, but is clumsy. With direct kernel-side arena access now in place, build the cmask in the arena. The kernel writes to it through the kern_va side of the dual mapping. BPF directly dereferences it via an __arena pointer like any other arena struct. Signed-off-by: Tejun Heo Reviewed-by: Emil Tsalapatis

sched_ext: Track bits[] storage size in struct scx_cmask

2026-05-21T07:14:39+00:00

scx_cmask carries @base and @nr_cids but not the bits[] allocation size, so helpers reshaping the active range have no way to check it fits and later kfuncs taking caller-provided storage can't validate it. Add @alloc_words (u64 word count) annotated with __counted_by, and split the bit-range API into three helpers: - SCX_CMASK_DEFINE() / __SCX_CMASK_DEFINE() define an on-stack cmask, the latter taking an explicit capacity for oversized storage. SCX_CMASK_DEFINE_SHARD() is a thin wrapper that always reserves SCX_CID_SHARD_MAX_CPUS bits of storage. - scx_cmask_init() / __scx_cmask_init() initialize a cmask, with the same tight-vs-explicit split. - scx_cmask_reframe() reshapes the active range without resizing storage. The BPF mirror (cmask_init / __cmask_init / cmask_reframe) gets the same shape. Add scx_cmask_clear() and scx_cmask_fill() to zero and set the active-range bits respectively. scx_cpumask_to_cmask() uses scx_cmask_clear(); scx_cmask_init() would otherwise re-write @alloc_words on every call. A later patch uses @alloc_words in scx_cmask_ref_shard() to refuse output storage that can't hold the requested shard. v2: Init per-CPU scx_set_cmask_scratch (was zero-init, emitted empty cmasks). Add nr_cids/alloc_cids check in BPF __cmask_init(). (sashiko AI) Widen SCX_CMASK_NR_WORDS()/CMASK_NR_WORDS() to compute in u64 so that @nr_cids near U32_MAX no longer wraps to a small value and bypasses the bounds check in cmask_reframe(). (Andrea) Signed-off-by: Tejun Heo Reviewed-by: Andrea Righi

sched_ext: Rename scx_cmask.nr_bits to nr_cids

2026-05-21T07:14:32+00:00

struct scx_cmask is a base-windowed bitmap over cid space. Each bit represents one cid, so the count of active bits is the count of cids. The sibling struct scx_cid_shard already uses nr_cids. Rename as a prep so the following patches that grow the cmask API can use the consistent name. v2: Also rename src->nr_bits / dst->nr_bits in cmask_copy_from_kernel(). (sashiko AI) Signed-off-by: Tejun Heo Reviewed-by: Andrea Righi

sched_ext: Add bpf_sched_ext_ops_cid struct_ops type

2026-04-29T18:25:07+00:00

cpumask is awkward from BPF and unusable from arena; cid/cmask work in both. Sub-sched enqueue will need cmask. Without a full cid interface, schedulers end up mixing forms - a subtle-bug factory. Add sched_ext_ops_cid, which mirrors sched_ext_ops with cid/cmask replacing cpu/cpumask in the topology-carrying callbacks. cpu_acquire/cpu_release are deprecated and absent; a prior patch moved them past @priv so the cid-form can omit them without disturbing shared-field offsets. The two structs share byte-identical layout up to @priv, so the existing bpf_scx init/check hooks, has_op bitmap, and scx_kf_allow_flags[] are offset-indexed and apply to both. BUILD_BUG_ON in scx_init() pins the shared-field and renamed-callback offsets so any future drift trips at boot. The kernel<->BPF boundary translates between cpu and cid: - A static key, enabled on cid-form sched load, gates the translation so cpu-form schedulers pay nothing. - dispatch, update_idle, cpu_online/offline and dump_cpu translate the cpu arg at the callsite. - select_cpu also translates the returned cid back to a cpu. - set_cpumask is wrapped to synthesize a cmask in a per-cpu scratch before calling the cid-form callback. All scheds in a hierarchy share one form. The static key drives the hot-path branch. v2: Use struct_size() for the set_cmask_scratch percpu alloc. Move cid-shard fields and assertions into the later cid-shard patch. v3: Drop `static` on scx_set_cmask_scratch; add extern in ext_internal.h. Signed-off-by: Tejun Heo Reviewed-by: Cheng-Yang Chou Reviewed-by: Changwoo Min Reviewed-by: Andrea Righi

sched_ext: Add cid-form kfunc wrappers alongside cpu-form

2026-04-29T18:25:07+00:00

cpumask is awkward from BPF and unusable from arena; cid/cmask work in both. Sub-sched enqueue will need cmask. Without full cid coverage a scheduler has to mix cid and cpu forms, which is a subtle-bug factory. Close the gap with a cid-native interface. Pair every cpu-form kfunc that takes a cpu id with a cid-form equivalent (kick, task placement, cpuperf query/set, per-cpu current task, nr-cpu-ids). Add two cid-natives with no cpu-form sibling: scx_bpf_this_cid() (cid of the running cpu, scx equivalent of bpf_get_smp_processor_id) and scx_bpf_nr_online_cids(). scx_bpf_cpu_rq is deprecated; no cid-form counterpart. NUMA node info is reachable via scx_bpf_cid_topo() on the BPF side. Each cid-form wrapper is a thin cid -> cpu translation that delegates to the cpu path, registered in the same context sets so usage constraints match. Signed-off-by: Tejun Heo Reviewed-by: Cheng-Yang Chou Reviewed-by: Changwoo Min Reviewed-by: Andrea Righi

sched_ext: Add cmask, a base-windowed bitmap over cid space

2026-04-29T18:25:07+00:00

Sub-scheduler code built on cids needs bitmaps scoped to a slice of cid space (e.g. the idle cids of a shard). A cpumask sized for NR_CPUS wastes most of its bits for a small window and is awkward in BPF. scx_cmask covers [base, base + nr_bits). bits[] is aligned to the global 64-cid grid: bits[0] spans [base & ~63, (base & ~63) + 64). Any two cmasks therefore address bits[] against the same global windows, so cross-cmask word ops reduce to dest->bits[i] OP= operand->bits[i - delta] with no bit-shifting, at the cost of up to one extra storage word for head misalignment. This alignment guarantee is the reason binary ops can stay word-level; every mutating helper preserves it. Kernel side in ext_cid.[hc]; BPF side in tools/sched_ext/include/scx/ cid.bpf.h. BPF side drops the scx_ prefix (redundant in BPF code) and adds the extra helpers that basic idle-cpu selection needs. No callers yet. v2: Narrow to helpers that will be used in the planned changes; set/bit/find/zero ops will be added as usage develops. v3: cmask_copy_from_kernel: validate src->base == 0 via probe-read; bit-level nr_bits check instead of round-up word count. (Sashiko) v4: Bump CMASK_CAS_TRIES to 1<<23 so abort fires only after seconds of real spinning, not on plausible contention. Switch __builtin_ctzll() to the ctzll() wrapper for clang compat (Changwoo). Signed-off-by: Tejun Heo Reviewed-by: Cheng-Yang Chou Reviewed-by: Changwoo Min Reviewed-by: Andrea Righi

tools/sched_ext: Add struct_size() helpers to common.bpf.h

2026-04-29T18:25:07+00:00

Add flex_array_size(), struct_size() and struct_size_t() to scx/common.bpf.h so BPF schedulers can size flex-array-containing structs the same way kernel code does. These are abbreviated forms of the macros. v3: Use offsetof() instead of sizeof() in struct_size() to match kernel semantics (no inflation from trailing struct padding). (Sashiko) Signed-off-by: Tejun Heo Reviewed-by: Cheng-Yang Chou Reviewed-by: Changwoo Min Reviewed-by: Andrea Righi