From 6579dcb5e0f7460ea004c7decd37adfc26dee84e Mon Sep 17 00:00:00 2001 From: Luka Gejak Date: Mon, 18 May 2026 16:23:10 +0200 Subject: wifi: rtw88: increase TX report timeout to fix race condition commit c80788f7c5aed8d420366b821f867a8a353d83a5 upstream. The driver expects the firmware to report TX status within 500ms. However, a timeout can be triggered when the hardware performs background scans while under TX load. During these scans, the firmware stays off-channel for periods exceeding 500ms, delaying the delivery of TX reports back to the driver. When this occurs, the purge timer fires prematurely and drops the tracking skbs from the queue. This results in the host stack interpreting the missing status as packet loss, leading to TCP window collapse. In testing with iperf3, this causes throughput to drop from ~90 Mbps to near-zero for approximately 2 seconds until the connection recovers. Increase RTW_TX_PROBE_TIMEOUT to 2500ms for RTL8723DU. This duration is sufficient to accommodate off-channel dwell time during full background scans, ensuring the purge timer only trips during genuine firmware lockups and preventing unnecessary TCP retransmission cycles. Fixes: a82dfd33d123 ("wifi: rtw88: Add common USB chip support") Cc: stable@vger.kernel.org Acked-by: Ping-Ke Shih Tested-by: Luka Gejak Signed-off-by: Luka Gejak Signed-off-by: Ping-Ke Shih Link: https://patch.msgid.link/20260518142311.10328-1-luka.gejak@linux.dev Signed-off-by: Greg Kroah-Hartman --- drivers/net/wireless/realtek/rtw88/tx.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/drivers/net/wireless/realtek/rtw88/tx.c b/drivers/net/wireless/realtek/rtw88/tx.c index f63900b6621d..2122ff5ab50a 100644 --- a/drivers/net/wireless/realtek/rtw88/tx.c +++ b/drivers/net/wireless/realtek/rtw88/tx.c @@ -190,6 +190,7 @@ void rtw_tx_report_purge_timer(struct timer_list *t) void rtw_tx_report_enqueue(struct rtw_dev *rtwdev, struct sk_buff *skb, u8 sn) { struct rtw_tx_report *tx_report = &rtwdev->tx_report; + unsigned long timeout = RTW_TX_PROBE_TIMEOUT; unsigned long flags; u8 *drv_data; @@ -201,7 +202,11 @@ void rtw_tx_report_enqueue(struct rtw_dev *rtwdev, struct sk_buff *skb, u8 sn) __skb_queue_tail(&tx_report->queue, skb); spin_unlock_irqrestore(&tx_report->q_lock, flags); - mod_timer(&tx_report->purge_timer, jiffies + RTW_TX_PROBE_TIMEOUT); + if (rtwdev->chip->id == RTW_CHIP_TYPE_8723D && + rtwdev->hci.type == RTW_HCI_TYPE_USB) + timeout = msecs_to_jiffies(2500); + + mod_timer(&tx_report->purge_timer, jiffies + timeout); } EXPORT_SYMBOL(rtw_tx_report_enqueue); -- cgit v1.2.3