wireguard-linux/tools/sched_ext/include, branch stable

sched_ext: Add a size argument to scx_bpf_cid_topo() so struct scx_cid_topo can grow

2026-09-26T20:09:12Z

scx_bpf_cid_topo() copies struct scx_cid_topo into a buffer the BPF program sized from its own vmlinux.h while the verifier sizes the write from the running kernel's BTF. The struct may grow and each growth then breaks every scheduler built against the older layout, rejected at load or written past its buffer. This is the usual hole for a struct handed to BPF, closed elsewhere with a size argument, and it was missed here. Take the buffer size, copy the smaller of it and the kernel's struct and set the rest to -1. Accesses to the copy are CO-RE relocated, so the struct can grow by appending fields, which its comment now states. The kfunc changes in place: the cid interface is still being finalized and no released scheduler uses the current form. Fixes: e9b55af47edf ("sched_ext: Add topological CPU IDs (cids)") Cc: stable@vger.kernel.org # v7.2+ Signed-off-by: Tejun Heo Reviewed-by: Andrea Righi

sched_ext: Maintain an online cid mask in the scheduler arena

2026-09-15T16:57:20Z

Schedulers on the default cid mapping treat [0, nr_online_cids) as the online set and restart on hotplug. Schedulers that install their own mapping with scx_bpf_cid_override() have no way to learn which cids are online: the count no longer identifies members and the CPU-form cpumask is unusable from cid programs. This is an obvious hole in the cid API. Add scx_bpf_online_cmask(), a kernel-maintained cmask in the scheduler's arena, allocated alongside the per-CPU scratch masks and populated after the cid mapping is finalized and before ops.init(), for child schedulers too. The pointer stays valid through ops.exit() with no reference to take. It is the arena offset as a void pointer, the same form struct_ops arena arguments arrive in. The verifier types the void return as a scalar for the program's arena cast. The mask follows the SCX hotplug notifications: seeded from cpu_active_mask and updated before ops.cid_online/offline() runs, so it lags cpu_online_mask only inside a hotplug transition. Updates walk the scheduler list under the lock that also serializes unlinking. Reads are live, not atomic snapshots. Root initialization excludes hotplug. v2: Reworded the getter kerneldoc (Andrea Righi). Signed-off-by: Tejun Heo Reviewed-by: Andrea Righi

sched_ext: Sync common and compat headers from the scx repo

2026-08-22T07:19:26Z

Sync common.bpf.h, compat.bpf.h and compat.h with the scx repo, which accumulated the following: - __COMPAT_read_enum() can now recover 64-bit scx enum values from kernel BTF generated without BTF_KIND_ENUM64 support (pahole < 1.24 or --skip_encoding_btf_enum64, e.g. COS/GKE kernels), substituting values from the build-time vmlinux.h cross-checked against the low 32 bits the kernel does provide. - is_migration_disabled() no longer assumes the BPF prolog always disables migration. Since 8e4f0b1ebcf2 ("bpf: use rcu_read_lock_dont_migrate() for trampoline.c") the prolog only does so under CONFIG_PREEMPT_RCU, so the old current-task test under-reported on v6.18+ !PREEMPT_RCU kernels. A runtime probe on bpf_scx_reg() handles older kernels with backported trampoline behavior. - __COMPAT_scx_bpf_dsq_peek() is gated behind kernel v7.1 where 2f2ea7709266 ("sched_ext: Use dsq->first_task instead of list_empty() in dispatch_enqueue() FIFO-tail") fixed the kfunc spuriously returning NULL on non-empty FIFO DSQs, and the new scx_bpf_reenqueue_local_from_anywhere() provides a callable-from-anywhere reenqueue which prefers the generic scx_bpf_dsq_reenq(). Both were first posted by Gavin Guo and Changwoo Min and are picked up here with the review feedback folded in. - __COMPAT_scx_bpf_cpu_curr() and the scx_bpf_cpu_rq() declaration are restored. Schedulers built from these headers still run on pre-v6.18 kernels where scx_bpf_cpu_curr() does not resolve and the scx_bpf_cpu_rq() fallback still exists. - scx_clock_task() and scx_clock_pelt() document their stale-read behavior for remote idle CPUs under NO_HZ_IDLE. Link: https://lore.kernel.org/all/20260817143126.562923-1-changwoo@igalia.com Signed-off-by: Tejun Heo

sched_ext: Sync tools autogen enum headers from the scx repo

2026-08-22T07:19:26Z

Regenerate enum_defs.autogen.h against the current tree, picking up the dispatch verdict enums and dropping the marker for the removed SCX_RQ_IN_BALANCE. Add enums_abi.autogen.h, a table of 64-bit scx enumerator values generated from vmlinux.h, used as the substitution source when the running kernel's BTF truncates 64-bit enum values to 32 bits. Signed-off-by: Tejun Heo

sched_ext: Merge branch 'for-7.3-arena-args' into for-7.3

2026-08-17T21:20:34Z

Pull to receive the __arena argument conversion: 67f1f4a48c24 ("sched_ext: Pass kernel arena pointers to ops_cid callbacks") a8dc810968af ("sched_ext: Convert sub-cap kfuncs to __arena cmask arguments") a05c5b5cb5cf ("sched_ext: Convert scx_bpf_cid_override() to __arena array arguments") along with the bpf-next branch carrying the __arena argument support they depend on. Conflict in kernel/sched/ext/ext.c between: c384ab8a0b13 ("sched_ext: Move the config-off sub-cap kfunc stubs into sub.c") and: a8dc810968af ("sched_ext: Convert sub-cap kfuncs to __arena cmask arguments") which updated the stubs in their old ext.c location. Resolved by keeping ext.c without the stubs and applying the prototype conversion to the relocated stubs in sub.c. Signed-off-by: Tejun Heo

sched_ext: Rename balance-era identifiers to dispatch terms

2026-08-15T10:07:42Z

sched_class->balance() is gone from sched_ext and what balance_one() does is run dispatch to produce something pickable. Update the balance-era names to dispatch terms: - balance_one() -> dispatch_one() - SCX_RQ_IN_BALANCE -> SCX_RQ_IN_DISPATCH No BPF scheduler reads the flag. The enum autogen headers gain the new name with the old entry retained like other removed enumerators, zero-filling at load time. No functional changes. Signed-off-by: Tejun Heo

sched_ext: Fix scx_bpf_dsq_move_to_local___v2 compat detection

2026-08-15T09:50:47Z

libbpf strips the last ___flavor suffix when resolving kfunc externs, so the bare ___v2 declaration resolves to scx_bpf_dsq_move_to_local, whose BTF proto lacks @enq_flags. The extern never matches, bpf_ksym_exists() returns false on every kernel that has the ___v2 kfunc, and the macro falls back to ___v1, silently dropping @enq_flags. Add the trailing ___compat suffix used by the other versioned externs in this file (scx_bpf_dsq_insert___v2, scx_bpf_reenqueue_local___v2). Any caller passing non-zero @enq_flags through the compat macro silently loses them. Fixes: 860683763ebf ("sched_ext: Add enq_flags to scx_bpf_dsq_move_to_local()") Cc: stable@vger.kernel.org # v7.1+ Assisted-by: Z.ai:glm-5.2 Signed-off-by: fangqiurong Signed-off-by: Tejun Heo

sched_ext: Fix scx_bpf_dsq_reenq___compat kfunc extern prototype

2026-08-14T21:00:56Z

scx_bpf_dsq_reenq() is registered with KF_IMPLICIT_ARGS and its kernel BTF prototype omits the trailing bpf_prog_aux argument. The ___compat extern declares the argument explicitly, so libbpf never matches the prototype and the weak extern silently stays unresolved on every kernel. The wrapper always takes the old fallback path, which disables generic reenq users like scx_qmap's lowpri mechanism and fails non-local reenq with "kernel too old" even on kernels that have the kfunc. Drop the explicit aux argument. Also correct the stale v6.20 reference, the kfunc was added in v7.1. Fixes: 9c34c5074d1b ("sched_ext: Introduce scx_bpf_dsq_reenq() for remote local DSQ reenqueue") Cc: stable@vger.kernel.org # v7.1+ Signed-off-by: Tejun Heo

sched_ext: Convert scx_bpf_cid_override() to __arena array arguments

2026-08-12T19:55:33Z

scx_bpf_cid_override() predates the cid-form arena transition and takes its arrays as verifier-checked mem+size buffers, forcing scx_qmap to keep the cpu_to_cid and shard_start arrays in writable bss while the rest of its state lives in the arena. Unify on arena arguments before cid-form schedulers start seeing real use. BPF now translates between BPF and kernel arena addresses for __arena arguments. Take the arrays as __arena arguments, with the counts passed in entries. The counts now size the snapshot copies and are bounds-checked before them. scx_qmap moves the arrays into struct qmap_arena. As the arena is mmapped at load, the loader populates them between load and attach instead of before load. The arena argument address translation is currently implemented only on x86-64. Schedulers calling this kfunc load only there for now. Signed-off-by: Tejun Heo

sched_ext: Convert sub-cap kfuncs to __arena cmask arguments

2026-08-12T19:55:33Z

The sub-cap kfuncs take their cmask arguments as __ign pointers. The values cross the kfunc boundary as unchecked scalars and scx_cmask_ref_init() rebases them into the arena by hand. BPF now translates between BPF and kernel arena addresses for __arena arguments. Tag the cmask arguments __arena so the kfuncs receive kernel addresses and scx_cmask_ref_init() loses the hand-rolled conversion. The optional denied_out keeps its NULL not-provided signal via __arena__nullable. The mandatory masks use plain __arena. scx_qmap's call sites drop the (void *)(long) casts since the BPF-side declarations type the cmask arguments __arena and take arena pointers directly. The arena argument address translation is currently implemented only on x86-64. Schedulers calling these kfuncs load only there for now. Signed-off-by: Tejun Heo