[PATCHSET v2 sched_ext/for-7.2] sched_ext: cmask improvements

[Tejun Heo <tj@kernel.org>]

Hello,

v2 rolls up the per-patch updates that went out in reply to v1 and
includes an update from Andrea's review on 2/3.

v1: https://lore.kernel.org/r/20260517183614.1191534-1-tj@kernel.org

v2:
- 1/3: Also rename nr_bits in cmask_copy_from_kernel().
- 2/3: Init scx_set_cmask_scratch. Bounds-check __cmask_init().
  Widen *_CMASK_NR_WORDS() to u64. (Andrea)
- 3/3: Add scx_cmask_empty().

Three patches for cmask: tidy active-range bookkeeping and add the
mask-on-mask op helpers the sub-sched series will use.

Not backward-compat with the current scx_cmask layout/API, but cmask
landed in for-7.2 and hasn't been released; scx_qmap is the only user.

 0001 - sched_ext: Rename scx_cmask.nr_bits to nr_cids
 0002 - sched_ext: Track bits[] storage size in struct scx_cmask
 0003 - sched_ext: Add cmask mask ops

Based on sched_ext/for-7.2 (1136fb1213d1).

Git tree: git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext.git cmask-prep-v2.3

 kernel/sched/ext_cid.c                | 322 +++++++++++++++++++++++++++++++++-
 kernel/sched/ext_cid.h                |  72 +++++++-
 kernel/sched/ext_types.h              |  68 +++++--
 tools/sched_ext/include/scx/cid.bpf.h | 144 ++++++++++-----
 4 files changed, 545 insertions(+), 61 deletions(-)

Thanks.

--
tejun