Patch C v3 — match cw1200 mainline architecture
(drivers/net/wireless/st/cw1200/). Eliminates the
sdio_rx_work workqueue relay that introduced a thread-safety
race on hw_priv->hw_bufs_used in v1 (PR #3 closed) and that
v2's atomic_t prep was a workaround for (PR #10 superseded by
v3 plan PR #11).
Architectural changes:
- bes2600_gpio_irq_handler: now calls self->irq_handler()
directly instead of queue_work(self->sdio_wq, &self->rx_work).
Bumps bh_rx atomic + wakes bh_wq.
- bes2600_bh_rx_helper (BES_SDIO_RX_MULTIPLE_ENABLE branch):
now calls priv->sbus_ops->bus_rx_batch() to do the SDIO read
inline. No pipe_read, no skb_dequeue.
- bes2600_sdio_read_rx_batch (new): the SDIO read sequence
extracted from sdio_rx_work, registered as
sbus_ops->bus_rx_batch. Runs in bh thread context.
- bes2600_sdio_extract_packets: calls
bes2600_bh_handle_rx_skb() directly per parsed SKB. No
skb_queue_tail, no rx_queue.
- bes2600_bh_handle_rx_skb (new in bh.c): the per-SKB
bookkeeping that bh_rx_helper used to do post-pipe_read
(seq# check, exception, confirm-condition, wsm_handle_rx).
Wakes bh thread for tx-burst via atomic_inc(&priv->bh_tx)
instead of bes2600_bh_wakeup() — we ARE the bh thread.
- Post-tx queue_work(rx_work) site: replaced with
self->irq_handler() to wake bh for piggyback RX check.
Deleted infrastructure:
- struct sbus_priv: rx_queue, rx_queue_lock, rx_work fields
- bes2600_sdio_pipe_read: function deleted (unused)
- sdio_rx_work: function deleted (unused)
- sbus_ops->pipe_read assignment: removed for SDIO bus
- skb_queue_head_init(&self->rx_queue), spin_lock_init(...),
INIT_WORK(rx_work): probe-time setup removed
- cancel_work_sync(rx_work) + drain loop in empty_work: removed
- flush_work(rx_work) in drain helper: replaced with msleep(2)
- work_pending(rx_work) check in suspend predicate: removed
Concurrency invariant restored:
- hw_priv->hw_bufs_used: single-writer (bh thread only)
by construction. No atomic_t needed.
- hw_priv->hw_bufs_used_vif[]: ditto.
- hw_priv->wsm_tx_pending[]: ditto.
- All other shared state: unchanged or already protected.
Phase 7 partial verification (rep 1, 2026-05-07):
- Module loads clean, srcversion 371C6606B73AF19299228CA
- Link associates, no WARN/BUG/oops
- sdio_rx_work dispatches: 0 (function deleted)
- bes2600_bh_work redispatches: 0 (single long-lived
invariant preserved)
- Chip handled stress traffic without wedge
Phase 7 full N=3 stress ramp deferred to follow-up rep series
(rep 2 had a TCP-level nc race; not a bes2600 issue but
invalidated rep 2's throughput number).
test0r