[PATCH ath-next v5 8/9] wifi: ath11k: stop a scheduling round when the hardware refuses a frame

[Julius Bairaktaris]

ath11k_dp_tx() returns -ENOSPC when the MSDU idr is full and -ENOMEM
when no TCL descriptor is free or a DMA mapping fails; it frees the
frame, and the round then dequeues and frees the next frame of the same
flow. End the round on those errors and on -ENOSPC from a full
management queue, leaving the frames behind queued; other errors concern
only the frame. A category whose round ended this way or on a full TCL
ring may have nothing in flight, so mark it and start its round from the
next tx completion on the device.

Tested-on: IPQ8074 hw2.0 AHB WLAN.HK.2.9.0.1-02146-QCAHKSWPL_SILICONZ-1

Assisted-by: Claude:claude-opus-5-5
Signed-off-by: Julius Bairaktaris <julius at bairaktaris.de>
---
 drivers/net/wireless/ath/ath11k/core.h  |  2 ++
 drivers/net/wireless/ath/ath11k/dp_tx.c | 10 ++++++++-
 drivers/net/wireless/ath/ath11k/mac.c   | 30 +++++++++++++++++++------
 3 files changed, 34 insertions(+), 8 deletions(-)

diff --git a/drivers/net/wireless/ath/ath11k/core.h b/drivers/net/wireless/ath/ath11k/core.h
index 40895d276de5f..8b7bfb0cefcf2 100644
--- a/drivers/net/wireless/ath/ath11k/core.h
+++ b/drivers/net/wireless/ath/ath11k/core.h
@@ -713,6 +713,8 @@ struct ath11k {
 	 * other contexts that drive it
 	 */
 	spinlock_t txq_lock[IEEE80211_NUM_ACS];
+	/* access categories whose round ended for lack of room */
+	unsigned long txq_starved;
 
 	struct list_head arvifs;
 	/* should never be NULL; needed for regular htt rx */
diff --git a/drivers/net/wireless/ath/ath11k/dp_tx.c b/drivers/net/wireless/ath/ath11k/dp_tx.c
index 5bcdeeb7e65ad..fb6a43dc45b81 100644
--- a/drivers/net/wireless/ath/ath11k/dp_tx.c
+++ b/drivers/net/wireless/ath/ath11k/dp_tx.c
@@ -776,8 +776,16 @@ void ath11k_dp_tx_completion_handler(struct ath11k_base *ab, int ring_id)
 	/* A completion returns the airtime the frame was charged, which is
 	 * what an airtime-limited station in that access category is waiting
 	 * on. The arrivals that would otherwise start a round are themselves
-	 * queued behind that limit.
+	 * queued behind that limit. It also frees the ring space and MSDU ids
+	 * that a round ended early on any radio is waiting on.
 	 */
+	for (i = 0; i < ab->num_radios; i++) {
+		ar = ab->pdevs[i].ar;
+		if (unlikely(READ_ONCE(ar->txq_starved)))
+			push |= xchg(&ar->txq_starved, 0) <<
+				(i * IEEE80211_NUM_ACS);
+	}
+
 	for_each_set_bit(i, &push, ab->num_radios * IEEE80211_NUM_ACS)
 		ath11k_mac_tx_push_pending(ab->pdevs[i / IEEE80211_NUM_ACS].ar,
 					   i % IEEE80211_NUM_ACS);
diff --git a/drivers/net/wireless/ath/ath11k/mac.c b/drivers/net/wireless/ath/ath11k/mac.c
index d17f80cbcdb5d..6b9cc54a7f5cb 100644
--- a/drivers/net/wireless/ath/ath11k/mac.c
+++ b/drivers/net/wireless/ath/ath11k/mac.c
@@ -6519,9 +6519,9 @@ static int ath11k_mac_mgmt_tx(struct ath11k *ar, struct sk_buff *skb,
 	return 0;
 }
 
-static void ath11k_mac_op_tx(struct ieee80211_hw *hw,
-			     struct ieee80211_tx_control *control,
-			     struct sk_buff *skb)
+static int ath11k_mac_tx(struct ieee80211_hw *hw,
+			 struct ieee80211_tx_control *control,
+			 struct sk_buff *skb)
 {
 	struct ath11k_skb_cb *skb_cb = ATH11K_SKB_CB(skb);
 	struct ath11k *ar = hw->priv;
@@ -6553,7 +6553,7 @@ static void ath11k_mac_op_tx(struct ieee80211_hw *hw,
 				    ret);
 			ieee80211_free_txskb(ar->hw, skb);
 		}
-		return;
+		return ret;
 	}
 
 	if (control->sta)
@@ -6564,6 +6564,15 @@ static void ath11k_mac_op_tx(struct ieee80211_hw *hw,
 		ath11k_warn(ar->ab, "failed to transmit frame %d\n", ret);
 		ieee80211_free_txskb(ar->hw, skb);
 	}
+
+	return ret;
+}
+
+static void ath11k_mac_op_tx(struct ieee80211_hw *hw,
+			     struct ieee80211_tx_control *control,
+			     struct sk_buff *skb)
+{
+	ath11k_mac_tx(hw, control, skb);
 }
 
 void ath11k_mac_drain_tx(struct ath11k *ar)
@@ -10090,6 +10099,7 @@ static int ath11k_mac_tx_push_txq(struct ath11k *ar, struct ieee80211_txq *txq)
 	struct sk_buff *skb;
 	u32 ring_selector;
 	int num_free;
+	int ret;
 	u8 ring_id;
 
 	ring_selector = ar->ab->hw_params.hw_ops->get_ring_selector(txq->ac);
@@ -10099,7 +10109,8 @@ static int ath11k_mac_tx_push_txq(struct ath11k *ar, struct ieee80211_txq *txq)
 
 	/* ieee80211_tx_dequeue() applies the airtime queue limit, so a
 	 * selection ends where that limit binds or the queue empties. A full
-	 * TCL ring ends the whole round.
+	 * TCL ring ends the whole round, and so does a frame the hardware
+	 * refuses.
 	 */
 	while (1) {
 		if (unlikely(test_bit(ATH11K_FLAG_CRASH_FLUSH,
@@ -10123,9 +10134,12 @@ static int ath11k_mac_tx_push_txq(struct ath11k *ar, struct ieee80211_txq *txq)
 			break;
 		}
 
-		ath11k_mac_op_tx(hw, &control, skb);
+		ret = ath11k_mac_tx(hw, &control, skb);
 
 		spin_unlock_bh(&tx_ring->wake_tx_lock);
+
+		if (unlikely(ret == -ENOSPC || ret == -ENOMEM))
+			return ret;
 	}
 
 	return 0;
@@ -10143,8 +10157,10 @@ static void ath11k_mac_schedule_txq(struct ath11k *ar, u8 ac)
 		int ret = ath11k_mac_tx_push_txq(ar, txq);
 
 		ieee80211_return_txq(hw, txq, false);
-		if (unlikely(ret))
+		if (unlikely(ret)) {
+			set_bit(ac, &ar->txq_starved);
 			break;
+		}
 	}
 	ieee80211_txq_schedule_end(hw, ac);
 
-- 
2.53.0