[PATCHSET sched_ext/for-7.2] sched_ext: cid/cmask interface prep

[Tejun Heo <tj@kernel.org>]

Hello,

Three preparatory changes to the cid/cmask interface that landed in for-7.2
this cycle - a helper-argument reorder, two new helpers, and a kfunc
return-type change. Posting ahead of the merge window, in particular the
scx_bpf_kick_cid() return-type change in patch 3 - it changes a kfunc's
signature and is cleaner to settle before 7.2 ships.

- Patch 1 reorders the single-cid cmask helpers to (cid, mask), matching the
  kernel's index-first bit and cpumask predicates.
- Patch 2 adds scx_cmask_test() and scx_cmask_for_each_cid().
- Patch 3 switches scx_bpf_kick_cid() from void to s32 so future cap
  enforcement can surface failures. The cid interface has no external users
  yet, so the ABI change is safe now.

These are extracted from the in-development sub-scheduler series. Nothing
here depends on the rest of that work.

Base
----

sched_ext/for-7.2 (dad836524259)

 kernel/sched/ext.c                       | 13 ++++++++-----
 kernel/sched/ext_cid.c                   |  2 +-
 kernel/sched/ext_cid.h                   | 41 ++++++++++++++++++++++++++++----
 tools/sched_ext/include/scx/common.bpf.h |  2 +-
 4 files changed, 46 insertions(+), 12 deletions(-)

Thanks.

--
tejun