linux-toradex.git/tools/sched_ext/scx_sdt.bpf.c, branch master

tools/sched_ext: Fix off-by-one in scx_sdt payload zeroing

2026-04-06T18:06:24+00:00

scx_alloc_free_idx() zeroes the payload of a freed arena allocation
one word at a time. The loop bound was alloc->pool.elem_size / 8, but
elem_size includes sizeof(struct sdt_data) (the 8-byte union sdt_id
header). This caused the loop to write one extra u64 past the
allocation, corrupting the tid field of the adjacent pool element.

Fix the loop bound to (elem_size - sizeof(struct sdt_data)) / 8 so
only the payload portion is zeroed.

Test plan:
- Add a temporary sanity check in scx_task_free() before the free call:

  if (mval->data->tid.idx != mval->tid.idx)
      scx_bpf_error("tid corruption: arena=%d storage=%d",
                    mval->data->tid.idx, (int)mval->tid.idx);

- stress-ng --fork 100 -t 10 & sudo ./build/bin/scx_sdt

Without this fix, running scx_sdt under fork-heavy load triggers the
corruption error. With the fix applied, the same workload completes
without error.

Fixes: 36929ebd17ae ("tools/sched_ext: add arena based scheduler")
Signed-off-by: Cheng-Yang Chou 
Reviewed-by: Emil Tsalapatis 
Signed-off-by: Tejun Heo

sched_ext: Add enq_flags to scx_bpf_dsq_move_to_local()

2026-03-13T19:43:23+00:00

scx_bpf_dsq_move_to_local() moves a task from a non-local DSQ to the
current CPU's local DSQ. This is an indirect way of dispatching to a local
DSQ and should support enq_flags like direct dispatches do - e.g.
SCX_ENQ_HEAD for head-of-queue insertion and SCX_ENQ_IMMED for immediate
execution guarantees.

Add scx_bpf_dsq_move_to_local___v2() with an enq_flags parameter. The
original becomes a v1 compat wrapper passing 0. The compat macro is updated
to a three-level chain: v2 (7.1+) -> v1 (current) -> scx_bpf_consume
(pre-rename). All in-tree BPF schedulers are updated to pass 0.

Signed-off-by: Tejun Heo 
Reviewed-by: Andrea Righi

tools/sched_ext: Fix data header access during free in scx_sdt

2026-02-02T15:50:14+00:00

Fix a pointer arithmetic error in scx_sdt during freeing that
causes the allocator to use the wrong memory address for the
allocation's data header.

Fixes: 36929ebd17ae ("tools/sched_ext: add arena based scheduler")
Signed-off-by: Emil Tsalapatis 
Acked-by: Andrea Righi 
Signed-off-by: Tejun Heo

tools/sched_ext: Add error logging for dsq creation failures in remaining schedulers

2026-02-01T17:10:18+00:00

Add scx_bpf_error() calls when scx_bpf_create_dsq() fails in the remaining
schedulers to improve debuggability:

- scx_simple.bpf.c: simple_init()
- scx_sdt.bpf.c: sdt_init()
- scx_cpu0.bpf.c: cpu0_init()
- scx_flatcg.bpf.c: fcg_init()

This follows the same pattern established in commit 2f8d489897ae
("sched_ext: Add error logging for dsq creation failures") for other
schedulers and ensures consistent error reporting across all schedulers.

Signed-off-by: zhidao su 
Signed-off-by: Tejun Heo

tools/sched_ext: add arena based scheduler

2026-01-28T01:43:34+00:00

Add a scheduler that uses BPF arenas to manage task context data.

Signed-off-by: Emil Tsalapatis 
Signed-off-by: Tejun Heo