bes2600: bus_reset on connection-loss storm to dodge assoc-comeback blackhole

When mac80211 declares connection loss against this AP (typically driven
by inactivity-deauth or beacon-loss), the userspace reauth that follows
sometimes enters a long blackhole: the AP responds to auth with success
but defers assoc with the 802.11v "assoc comeback" timer; ohm retries
faster than the comeback grants permission; the AP eventually fires an
unprotected deauth-reason-6 ("Class 2 frame received from non-
authenticated station"), and recovery only completes via cross-SSID or
cross-channel fallback. Receipts: ~86 s blackhole observed in the
phase-7 rep on 2026-05-07 02:42, with three subsequent BSSIDs returning
assoc comeback timeouts before reason-9 (STA_REQ_ASSOC_WITHOUT_AUTH)
fired. Documented in marfrit/besser:notes/phase4-2026-05-07.md.

When N=3 driver-side connection_loss decisions fire within a 60 s window
on the same vif, skip the ieee80211_connection_loss() path and trigger
the c5.2-introduced bes2600_chrdev_do_bus_reset() instead. The bus
reset removes and re-probes the chip; userspace re-associates with a
fresh chip state, dodging the AP's comeback-timer rejection cycle.

Predicted Phase 7 delta vs current baseline:
- api_connection_loss rate: unchanged (we don't address the trigger)
- conditional probability of >5 s blackhole given event: <= 30 %
- worst-case recovery: 86 s -> < 10 s

Contract pin: bes2600_chrdev_do_bus_reset(sbus_ops, sbus_priv) at
bes2600/bes_chardev.c:455, introduced by c5.2. The function is async-
returning: sbus_ops->bus_reset() schedules an SDIO rescan; the helper
waits up to 3 s for the remove() callback to clear sbus_priv, then
returns. Per-vif state is gone after this point, so the recover work
lives on bes2600_common (hw_priv) and uses the global bes2600_cdev for
the bus_reset call rather than dereferencing per-vif state.

Threshold (3 / 60 s) is well above the steady-state per-vif
connection_loss rate observed in the patch-A phase-7 rep (0.86/h under
sustained load), so a true storm is required to trip it.

Files touched:
- bes2600/bes2600.h: 3 counter fields on struct bes2600_vif, 1
  work_struct on struct bes2600_common, 3 prototypes
- bes2600/sta.c: 3 helpers + storm-account hook in
  bes2600_connection_loss_work + storm-init in bes2600_vif_setup +
  cancel_work_sync in the hw_priv shutdown path; #include bes_chardev.h
  was already pulled in by an earlier c-stack patch
- bes2600/main.c: INIT_WORK alongside other hw_priv work_structs
- bes2600/debug.c: ConnectionLossStormRecoveries seq_printf in the
  per-vif status seq_file output

The cw1200/cw1260 ancestor has no equivalent; this is a clean
addition. checkpatch.pl --no-tree --strict: clean (0/0/0).

Signed-off-by: Claude (noether) <claude@reauktion.de>
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

bes2600/bes2600_sdio.c

@@ -29,7 +29,6 @@
 #include <linux/of_gpio.h>
 
 #include "bes2600.h"
-#include "bh.h"
 #include "sbus.h"
 #include "bes2600_plat.h"
 #include "bes2600_factory.h"
@@ -813,23 +812,10 @@ static int bes2600_sdio_extract_packets(struct sbus_priv *self, u32 ctrl_reg, u8
 		skb_put(skb, packet_len);
 		memcpy(skb->data, &data[pos], packet_len);
 		bes_devel("%s, %d,%d\n", __func__, packet_len, pos);
+		spin_lock(&self->rx_queue_lock);
+		skb_queue_tail(&self->rx_queue, skb);
 		self->rx_data_cnt++;
-		/*
+		spin_unlock(&self->rx_queue_lock);
-		 * Patch C: deliver SKB directly into the WSM/mac80211 stack
-		 * instead of skb_queue_tail-ing onto self->rx_queue for later
-		 * pickup by the bh thread.  Removes two spinlock acquires
-		 * (rx_queue->lock at queue-tail + at dequeue) per RX frame
-		 * and one bh wait-queue wake-up per IRQ batch.
-		 *
-		 * bes2600_bh_handle_rx_skb owns the SKB on every path.
-		 * Contract: process context, sleepable, caller holds no
-		 * bes2600 spinlock.  See bh.c for the contract block.
-		 *
-		 * Pre-condition satisfied here: bes2600_sdio_unlock(self)
-		 * was called at the bottom of the SDIO read sequence in
-		 * sdio_rx_work, so we hold no bes2600 mutex either.
-		 */
-		bes2600_bh_handle_rx_skb(self->core, skb);
 		packet_len = (packet_len + 3) & (~0x3);
 		pos += packet_len;
 		#ifdef BES_SDIO_OPTIMIZED_LEN
@@ -912,17 +898,12 @@ static void sdio_rx_work(struct work_struct *work)
 
 		ctrl_reg = 0;
 
-		/*
+		if (likely(self->irq_handler)) {
-		 * Patch C: with direct delivery in extract_packets, the bh
+			self->irq_handler(self->irq_priv);
-		 * thread no longer drives RX consumption — there is no
+		} else {
-		 * rx_queue to drain.  Calling self->irq_handler() here would
+			bes_err("%s,%d\n", __func__, __LINE__);
-		 * wake the bh thread for nothing on every IRQ batch.  TX
+			goto failed;
-		 * wakes still flow through bes2600_bh_wakeup() from TX
+		}
-		 * submitters and from bes2600_bh_handle_rx_skb when a
-		 * confirm releases a TX buffer; early-boot IRQs (before
-		 * fw_started) still go through self->irq_handler from the
-		 * GPIO IRQ handler's fallback branch.
-		 */
 
 	} while (again);
 

bes2600/bh.c

@@ -958,115 +958,6 @@ static void bes2600_bh_parse_wakeup_event(struct bes2600_common *hw_priv, struct
 	}
 }
 
-/*
- * Direct-deliver an RX SKB into the WSM/mac80211 stack.
- *
- * Patch C (sdio_rx_work direct delivery): this function does the
- * per-SKB bookkeeping (sequence-number check, exception handling,
- * tx-confirm accounting, mac80211 hand-off via wsm_handle_rx) that
- * previously ran inside bes2600_bh_rx_helper after pipe_read dequeued
- * an SKB from sbus_priv->rx_queue.  It is now called inline from
- * bes2600_sdio_extract_packets, eliminating the queue + bh-wakeup
- * relay (one wait-queue wake-up + two rx_queue->lock acquires per
- * RX frame).
- *
- * Contract:
- *   - process context, sleepable.  wsm_handle_rx (wsm.c:2211, exported
- *     at wsm.c:2463) acquires wsm_cmd.lock, may call into mac80211
- *     and may sleep on wait_event_timeout (wsm.c:2036, 2091).
- *   - caller MUST hold no bes2600 spinlock.  Reference precedent:
- *     bes2600_bh_rx_helper (this file) called from the bh thread.
- *     The SDIO mutex is released at bes2600_sdio.c before
- *     extract_packets is called, so this is satisfied.
- *   - SKB ownership: function frees on every path (success and error).
- *   - Returns 0 on success, negative on error.  When the SKB carries
- *     a confirm that releases a TX buffer, the function asynchronously
- *     wakes the bh thread to drain TX (matches the in-bh tx=1
- *     signaling that bh_rx_helper used).
- */
-int bes2600_bh_handle_rx_skb(struct bes2600_common *priv, struct sk_buff *skb)
-{
-	struct wsm_hdr *wsm;
-	size_t wsm_len;
-	u16 wsm_id;
-	u8 wsm_seq;
-	int tx = 0;
-	u32 confirm_label = 0x0;
-
-	if (!skb)
-		return 0;
-
-	wsm = (struct wsm_hdr *)skb->data;
-	wsm_len = __le16_to_cpu(wsm->len);
-	if (WARN_ON(wsm_len > skb->len)) {
-		bes_err("wsm_len err %d %d\n", (int)wsm_len, (int)skb->len);
-		dev_kfree_skb(skb);
-		return -1;
-	}
-
-	if (priv->wsm_enable_wsm_dumps)
-		print_hex_dump(KERN_DEBUG, "<-- ", DUMP_PREFIX_NONE, 16, 1,
-			       skb->data, wsm_len, false);
-
-	wsm_id  = __le16_to_cpu(wsm->id) & 0xFFF;
-	wsm_seq = (__le16_to_cpu(wsm->id) >> 13) & 7;
-	bes_devel("bes2600_bh_handle_rx_skb wsm_id:0x%04x seq:%d\n",
-		  wsm_id, wsm_seq);
-
-	skb_trim(skb, wsm_len);
-
-	if (wsm_id == 0x0800) {
-		wsm_handle_exception(priv,
-				     &skb->data[sizeof(*wsm)],
-				     wsm_len - sizeof(*wsm));
-		bes_err("wsm exception\n");
-		dev_kfree_skb(skb);
-		return -1;
-	} else if ((wsm_seq != priv->wsm_rx_seq[WSM_TXRX_SEQ_IDX(wsm_id)])) {
-		bes_err("seq error! %u. %u. 0x%x.", wsm_seq,
-			priv->wsm_rx_seq[WSM_TXRX_SEQ_IDX(wsm_id)], wsm_id);
-		dev_kfree_skb(skb);
-		return -1;
-	}
-
-	bes2600_bh_parse_wakeup_event(priv, skb);
-
-	priv->wsm_rx_seq[WSM_TXRX_SEQ_IDX(wsm_id)] = (wsm_seq + 1) & 7;
-
-	if (IS_DRIVER_TO_MCU_CMD(wsm_id))
-		confirm_label = __le32_to_cpu(((struct wsm_mcu_hdr *)wsm)->handle_label);
-
-	if (WSM_CONFIRM_CONDITION(wsm_id, confirm_label)) {
-		int rc = wsm_release_tx_buffer(priv, 1);
-		bes2600_bh_dec_pending_count(priv, WSM_TXRX_SEQ_IDX(wsm->id));
-
-		if (rc < 0) {
-			bes_err("wsm_release_tx_buffer failed: %d\n", rc);
-			dev_kfree_skb(skb);
-			return rc;
-		} else if (rc > 0) {
-			tx = 1;
-		}
-	}
-
-	/* wsm_handle_rx takes care of SKB lifetime: zeroes *skb_p if consumed. */
-	if (wsm_handle_rx(priv, wsm_id, wsm, &skb)) {
-		bes_err("wsm_handle_rx failed (id=0x%04x)\n", wsm_id);
-		if (skb)
-			dev_kfree_skb(skb);
-		return -1;
-	}
-
-	if (skb)
-		dev_kfree_skb(skb);
-
-	if (tx)
-		bes2600_bh_wakeup(priv);
-
-	return 0;
-}
-EXPORT_SYMBOL(bes2600_bh_handle_rx_skb);
-
 static int bes2600_bh_rx_helper(struct bes2600_common *priv, int *tx)
 {
 	struct sk_buff *skb = NULL;

bes2600/bh.h

@@ -36,13 +36,6 @@ void bes2600_enable_powersave(struct bes2600_vif *priv,
 int wsm_release_tx_buffer(struct bes2600_common *hw_priv, int count);
 int wsm_release_vif_tx_buffer(struct bes2600_common *hw_priv, int if_id,
 				int count);
-/*
- * Direct-deliver an RX SKB into the WSM/mac80211 stack.
- * Process context, sleepable, caller holds no bes2600 spinlock.
- * Function frees skb on every path. See bh.c for full contract.
- */
-int bes2600_bh_handle_rx_skb(struct bes2600_common *hw_priv,
-			     struct sk_buff *skb);
 int bes2600_bh_sw_process(struct bes2600_common *hw_priv,
 			 struct wsm_tx_confirm *tx_confirm);