sched_ext: scx_qmap: replace FIFO queue maps with arena-backed lists

Arena simplifies verification and allows more natural programming.
Convert scx_qmap to arena as preparation for further sub-sched work.

Replace the five BPF_MAP_TYPE_QUEUE maps with doubly-linked lists in
arena, threaded through task_ctx. Each queue is a struct qmap_fifo with
head/tail pointers and its own per-queue bpf_res_spin_lock.

qmap_dequeue() now properly removes tasks from the queue instead of
leaving stale entries for dispatch to skip.

v2:
- Remove duplicate QMAP_TOUCH_ARENA() in qmap_dump_task (Andrea).
- Update file-level description for arena-backed lists (Andrea).

Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Andrea Righi <arighi@nvidia.com>
Reviewed-by: Emil Tsalapatis <emil@etsalapatis.com>

0 files changed, 0 insertions, 0 deletions