[PATCH] wifi: ath12k: fix flush failure in recovery scenarios

[Baochen Qiang <quic_bqiang@quicinc.com>]

Commit eaf9f17b861b ("wifi: ath12k: relocate ath12k_dp_pdev_pre_alloc()
call") moves ath12k_dp_pdev_pre_alloc() from ath12k_core_start() to
ath12k_mac_allocate(), resulting in ath12k_mac_flush() failure in
recovery scenarios:

[ 6849.684104] ath12k_pci 0000:04:00.0: pdev 0 successfully recovered
[ 6854.907320] ath12k_pci 0000:04:00.0: failed to flush transmit queue 0
[ 6860.027353] ath12k_pci 0000:04:00.0: failed to flush transmit queue 0
[ 6865.143385] ath12k_pci 0000:04:00.0: failed to flush transmit queue 0

This is because, with ath12k_dp_pdev_pre_alloc() moved to ath12k_mac_allocate(),
dp->num_tx_pending is not reset due to ATH12K_FLAG_REGISTERED set in
recovery scenarios.

So a possible fix would be to reset that counter at some proper point,
just like the old design. But considering that the counter tracks number
of packets pending to be freed or returned to mac80211, forcefully reset
it might make it hard to expose some real issues. For example if somehow
ath12k fails to free/return some TX packets, we don't know that because
no warnings any more.

That is to say we should not reset that counter during recovery (which is
already done due to above commit), instead should decrease it each time
a packet is freed/returned. Currently almost each related function has
this logic implemented, except ath12k_dp_cc_cleanup(). So add the same
there to fix this issue.

Tested-on: WCN7850 hw2.0 PCI WLAN.HMT.1.0-03427-QCAHMTSWPL_V1.0_V2.0_SILICONZ-1.15378.4

Signed-off-by: Baochen Qiang <quic_bqiang@quicinc.com>
---
 drivers/net/wireless/ath/ath12k/dp.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/net/wireless/ath/ath12k/dp.c b/drivers/net/wireless/ath/ath12k/dp.c
index 1006eef8ff0c..ddfe1eb82d6b 100644
--- a/drivers/net/wireless/ath/ath12k/dp.c
+++ b/drivers/net/wireless/ath/ath12k/dp.c
@@ -1150,7 +1150,9 @@ static void ath12k_dp_cc_cleanup(struct ath12k_base *ab)
 	struct ath12k_rx_desc_info *desc_info;
 	struct ath12k_tx_desc_info *tx_desc_info, *tmp1;
 	struct ath12k_dp *dp = &ab->dp;
+	struct ath12k_skb_cb *skb_cb;
 	struct sk_buff *skb;
+	struct ath12k *ar;
 	int i, j;
 	u32 pool_id, tx_spt_page;
 
@@ -1201,6 +1203,11 @@ static void ath12k_dp_cc_cleanup(struct ath12k_base *ab)
 			if (!skb)
 				continue;
 
+			skb_cb = ATH12K_SKB_CB(skb);
+			ar = skb_cb->ar;
+			if (atomic_dec_and_test(&ar->dp.num_tx_pending))
+				wake_up(&ar->dp.tx_empty_waitq);
+
 			dma_unmap_single(ab->dev, ATH12K_SKB_CB(skb)->paddr,
 					 skb->len, DMA_TO_DEVICE);
 			dev_kfree_skb_any(skb);

base-commit: fe7e1b830cf3c0272aa4eaf367c4c7b29c169c3d
-- 
2.25.1