linux-kernel - [PATCH AUTOSEL 4.19 21/59] ath10k: Fix tx hanging

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Message-Id: <20220118024701.1952911-21-sashal@kernel.org>
Date:   Mon, 17 Jan 2022 21:46:22 -0500
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Sebastian Gottschall <s.gottschall@...wrt.com>,
        Kalle Valo <quic_kvalo@...cinc.com>,
        Sasha Levin <sashal@...nel.org>, kvalo@...nel.org,
        davem@...emloft.net, kuba@...nel.org, ath10k@...ts.infradead.org,
        linux-wireless@...r.kernel.org, netdev@...r.kernel.org
Subject: [PATCH AUTOSEL 4.19 21/59] ath10k: Fix tx hanging

From: Sebastian Gottschall <s.gottschall@...wrt.com>

[ Upstream commit e8a91863eba3966a447d2daa1526082d52b5db2a ]

While running stress tests in roaming scenarios (switching ap's every 5
seconds, we discovered a issue which leads to tx hangings of exactly 5
seconds while or after scanning for new accesspoints. We found out that
this hanging is triggered by ath10k_mac_wait_tx_complete since the
empty_tx_wq was not wake when the num_tx_pending counter reaches zero.
To fix this, we simply move the wake_up call to htt_tx_dec_pending,
since this call was missed on several locations within the ath10k code.

Signed-off-by: Sebastian Gottschall <s.gottschall@...wrt.com>
Signed-off-by: Kalle Valo <quic_kvalo@...cinc.com>
Link: https://lore.kernel.org/r/20210505085806.11474-1-s.gottschall@dd-wrt.com
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/net/wireless/ath/ath10k/htt_tx.c | 3 +++
 drivers/net/wireless/ath/ath10k/txrx.c   | 2 --
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/net/wireless/ath/ath10k/htt_tx.c b/drivers/net/wireless/ath/ath10k/htt_tx.c
index fd011bdabb963..3718d4dfc6d60 100644
--- a/drivers/net/wireless/ath/ath10k/htt_tx.c
+++ b/drivers/net/wireless/ath/ath10k/htt_tx.c
@@ -158,6 +158,9 @@ void ath10k_htt_tx_dec_pending(struct ath10k_htt *htt)
 	htt->num_pending_tx--;
 	if (htt->num_pending_tx == htt->max_num_pending_tx - 1)
 		ath10k_mac_tx_unlock(htt->ar, ATH10K_TX_PAUSE_Q_FULL);
+
+	if (htt->num_pending_tx == 0)
+		wake_up(&htt->empty_tx_wq);
 }
 
 int ath10k_htt_tx_inc_pending(struct ath10k_htt *htt)
diff --git a/drivers/net/wireless/ath/ath10k/txrx.c b/drivers/net/wireless/ath/ath10k/txrx.c
index 6c47e4b6aa6cd..888a8f4aff5d8 100644
--- a/drivers/net/wireless/ath/ath10k/txrx.c
+++ b/drivers/net/wireless/ath/ath10k/txrx.c
@@ -91,8 +91,6 @@ int ath10k_txrx_tx_unref(struct ath10k_htt *htt,
 
 	ath10k_htt_tx_free_msdu_id(htt, tx_done->msdu_id);
 	ath10k_htt_tx_dec_pending(htt);
-	if (htt->num_pending_tx == 0)
-		wake_up(&htt->empty_tx_wq);
 	spin_unlock_bh(&htt->tx_lock);
 
 	dma_unmap_single(dev, skb_cb->paddr, msdu->len, DMA_TO_DEVICE);
-- 
2.34.1