[PATCH v3 12/12] ath11k: avoid unnecessary lock contention in tx_completion path

[P Praneesh <ppranees@xxxxxxxxxxxxxx>]

Avoid unnecessary idr_find calls before the idr_remove calls. Because
idr_remove gives the valid ptr if id is valid otherwise return NULL ptr.
So removed the idr_find before idr_remove in tx completion path. Also no
need to disable the bottom half preempt if it is already in the
bottom half context, so modify the spin_lock_bh to spin_lock in the
data tx completion path.

Tested-on: IPQ8074 hw2.0 AHB WLAN.HK.2.4.0.1-01734-QCAHKSWPL_SILICONZ-1 v2

Co-developed-by: Karthikeyan Periyasamy <periyasa@xxxxxxxxxxxxxx>
Signed-off-by: Karthikeyan Periyasamy <periyasa@xxxxxxxxxxxxxx>
Signed-off-by: Jouni Malinen <jouni@xxxxxxxxxxxxxx>
Signed-off-by: P Praneesh <ppranees@xxxxxxxxxxxxxx>
---
 drivers/net/wireless/ath/ath11k/dp_tx.c | 32 ++++++++++++++------------------
 1 file changed, 14 insertions(+), 18 deletions(-)

diff --git a/drivers/net/wireless/ath/ath11k/dp_tx.c b/drivers/net/wireless/ath/ath11k/dp_tx.c
index 602184b..05bd86f 100644
--- a/drivers/net/wireless/ath/ath11k/dp_tx.c
+++ b/drivers/net/wireless/ath/ath11k/dp_tx.c
@@ -288,20 +288,18 @@ static void ath11k_dp_tx_free_txbuf(struct ath11k_base *ab, u8 mac_id,
 	struct sk_buff *msdu;
 	struct ath11k_skb_cb *skb_cb;
 
-	spin_lock_bh(&tx_ring->tx_idr_lock);
-	msdu = idr_find(&tx_ring->txbuf_idr, msdu_id);
-	if (!msdu) {
+	spin_lock(&tx_ring->tx_idr_lock);
+	msdu = idr_remove(&tx_ring->txbuf_idr, msdu_id);
+	spin_unlock(&tx_ring->tx_idr_lock);
+
+	if (unlikely(!msdu)) {
 		ath11k_warn(ab, "tx completion for unknown msdu_id %d\n",
 			    msdu_id);
-		spin_unlock_bh(&tx_ring->tx_idr_lock);
 		return;
 	}
 
 	skb_cb = ATH11K_SKB_CB(msdu);
 
-	idr_remove(&tx_ring->txbuf_idr, msdu_id);
-	spin_unlock_bh(&tx_ring->tx_idr_lock);
-
 	dma_unmap_single(ab->dev, skb_cb->paddr, msdu->len, DMA_TO_DEVICE);
 	dev_kfree_skb_any(msdu);
 
@@ -320,12 +318,13 @@ ath11k_dp_tx_htt_tx_complete_buf(struct ath11k_base *ab,
 	struct ath11k_skb_cb *skb_cb;
 	struct ath11k *ar;
 
-	spin_lock_bh(&tx_ring->tx_idr_lock);
-	msdu = idr_find(&tx_ring->txbuf_idr, ts->msdu_id);
+	spin_lock(&tx_ring->tx_idr_lock);
+	msdu = idr_remove(&tx_ring->txbuf_idr, ts->msdu_id);
+	spin_unlock(&tx_ring->tx_idr_lock);
+
 	if (unlikely(!msdu)) {
 		ath11k_warn(ab, "htt tx completion for unknown msdu_id %d\n",
 			    ts->msdu_id);
-		spin_unlock_bh(&tx_ring->tx_idr_lock);
 		return;
 	}
 
@@ -334,9 +333,6 @@ ath11k_dp_tx_htt_tx_complete_buf(struct ath11k_base *ab,
 
 	ar = skb_cb->ar;
 
-	idr_remove(&tx_ring->txbuf_idr, ts->msdu_id);
-	spin_unlock_bh(&tx_ring->tx_idr_lock);
-
 	if (atomic_dec_and_test(&ar->dp.num_tx_pending))
 		wake_up(&ar->dp.tx_empty_waitq);
 
@@ -579,16 +575,16 @@ void ath11k_dp_tx_completion_handler(struct ath11k_base *ab, int ring_id)
 			continue;
 		}
 
-		spin_lock_bh(&tx_ring->tx_idr_lock);
-		msdu = idr_find(&tx_ring->txbuf_idr, msdu_id);
+		spin_lock(&tx_ring->tx_idr_lock);
+		msdu = idr_remove(&tx_ring->txbuf_idr, msdu_id);
 		if (unlikely(!msdu)) {
 			ath11k_warn(ab, "tx completion for unknown msdu_id %d\n",
 				    msdu_id);
-			spin_unlock_bh(&tx_ring->tx_idr_lock);
+			spin_unlock(&tx_ring->tx_idr_lock);
 			continue;
 		}
-		idr_remove(&tx_ring->txbuf_idr, msdu_id);
-		spin_unlock_bh(&tx_ring->tx_idr_lock);
+
+		spin_unlock(&tx_ring->tx_idr_lock);
 
 		ar = ab->pdevs[mac_id].ar;
 
-- 
2.7.4