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bes2600: Patch E — skip ps_state_lock when PSM-known-disabled

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Per the Opus structural critique (PR #8 §2.4) and Sonnet review item 5.
The per-RX-frame early-data path takes ps_state_lock to double-check
whether a link entry transitioned to BES2600_LINK_SOFT (AP-side
power-save state machine, soft-link transition).

When c7 has latched pm_unsupported = true (firmware does not honor
PSM, see feedback_bes2600_firmware_no_psm memory), the AP power-save
state machine is dead and link entries never transition to LINK_SOFT.
The per-frame spin_lock_bh + double-check is wasted work.

This patch gates the lock acquisition on !pm_unsupported.  When the
latch is on (the steady state on the production-shipped bes2600
firmware), early_data RX frames bypass the spin_lock_bh and go
directly to ieee80211_rx_irqsafe.

If a future firmware drop fixes PSM, c7 self-clears pm_unsupported on
the first real PM_INDICATION and the locked path resumes.

Scope is narrower than Sonnet originally framed: only the per-RX-frame
hot path (txrx.c:1945-1951 in cleanups+G+D) is touched.  Other
ps_state_lock sites in txrx.c (lines 657, 1256, 1420, 1528) are TX
submission / multicast-start / link-id paths, not per-frame RX, and
not on the Bug #5 hot path.  Leave those alone.

Build verified: srcversion B5922B4933590F33207EE97 on ohm sandbox.
This commit is contained in:
Markus Fritsche
2026-05-08 00:22:14 +02:00
parent 8fd20308ed
commit 445c619da8
1 changed files with 24 additions and 6 deletions
Download Patch File Download Diff File Expand all files Collapse all files
bes2600/txrx.c
+24 -6
View File
@@ -1965,13 +1965,31 @@ void bes2600_rx_cb(struct bes2600_vif *priv,
if (unlikely(bes2600_itp_rxed(hw_priv, skb)))
consume_skb(skb);
else if (unlikely(early_data)) {
spin_lock_bh(&priv->ps_state_lock);
/* Double-check status with lock held */
if (entry->status == BES2600_LINK_SOFT)
skb_queue_tail(&entry->rx_queue, skb);
else
/*
* Patch E: when c7 has latched pm_unsupported (firmware
* doesn't honour PSM, see feedback_bes2600_firmware_no_psm),
* AP-side power-save state machine is dead and link entries
* never transition to BES2600_LINK_SOFT. The double-check
* branch under ps_state_lock is unreachable in that case,
* so skip the per-frame lock acquisition entirely and
* deliver to mac80211 directly.
*
* On firmware that does honour PSM (the latch self-clears
* if a real PM_INDICATION ever arrives — see c7), this
* predicate flips back to false and the original locked
* path is taken.
*/
if (hw_priv->bes_power.pm_unsupported) {
ieee80211_rx_irqsafe(priv->hw, skb);
spin_unlock_bh(&priv->ps_state_lock);
} else {
spin_lock_bh(&priv->ps_state_lock);
/* Double-check status with lock held */
if (entry->status == BES2600_LINK_SOFT)
skb_queue_tail(&entry->rx_queue, skb);
else
ieee80211_rx_irqsafe(priv->hw, skb);
spin_unlock_bh(&priv->ps_state_lock);
}
} else {
ieee80211_rx_irqsafe(priv->hw, skb);
}