diff mbox series

[2/3] rtw88: Fix potential unrecoverable tx queue stop

Message ID 20210415084703.27255-3-pkshih@realtek.com
State Accepted
Commit a548909d7ad7e334c6c923a71f0b694d60980232
Delegated to: Kalle Valo
Headers show
Series rtw88: fix some TX/RX bugs | expand

Commit Message

Ping-Ke Shih April 15, 2021, 8:47 a.m. UTC
From: Yu-Yen Ting <steventing@realtek.com>

If there are lots of packets to be transmitted, the driver would check
whether the available descriptors are sufficient according the read/write
point of tx queue. Once the available descriptor is not enough,
ieee80211_stop_queue is called.

TX ISR, meanwhile, is releasing the tx resources after the packets are
transmitted. This routine may call ieee80211_wake_queue by checking the
available descriptor.

The potential queue stop problem would occur when the tx queue is
stopped due to the heavy traffic. Then thare is no chance to wake the
queue up because the read point is not updated immediately, as a result,
no more packets coulde be transmitted in this queue.

This patch makes sure the ieee80211_wake_queue could be called properly
and avoids the race condition when ring->r.rp, ring->queue_stopped are
updated.

Signed-off-by: Yu-Yen Ting <steventing@realtek.com>
Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
---
 drivers/net/wireless/realtek/rtw88/pci.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)
diff mbox series

Patch

diff --git a/drivers/net/wireless/realtek/rtw88/pci.c b/drivers/net/wireless/realtek/rtw88/pci.c
index b8115b31839e..adea3c7551ab 100644
--- a/drivers/net/wireless/realtek/rtw88/pci.c
+++ b/drivers/net/wireless/realtek/rtw88/pci.c
@@ -950,10 +950,12 @@  static int rtw_pci_tx_write(struct rtw_dev *rtwdev,
 		return ret;
 
 	ring = &rtwpci->tx_rings[queue];
+	spin_lock_bh(&rtwpci->irq_lock);
 	if (avail_desc(ring->r.wp, ring->r.rp, ring->r.len) < 2) {
 		ieee80211_stop_queue(rtwdev->hw, skb_get_queue_mapping(skb));
 		ring->queue_stopped = true;
 	}
+	spin_unlock_bh(&rtwpci->irq_lock);
 
 	return 0;
 }
@@ -968,7 +970,7 @@  static void rtw_pci_tx_isr(struct rtw_dev *rtwdev, struct rtw_pci *rtwpci,
 	struct sk_buff *skb;
 	u32 count;
 	u32 bd_idx_addr;
-	u32 bd_idx, cur_rp;
+	u32 bd_idx, cur_rp, rp_idx;
 	u16 q_map;
 
 	ring = &rtwpci->tx_rings[hw_queue];
@@ -977,6 +979,7 @@  static void rtw_pci_tx_isr(struct rtw_dev *rtwdev, struct rtw_pci *rtwpci,
 	bd_idx = rtw_read32(rtwdev, bd_idx_addr);
 	cur_rp = bd_idx >> 16;
 	cur_rp &= TRX_BD_IDX_MASK;
+	rp_idx = ring->r.rp;
 	if (cur_rp >= ring->r.rp)
 		count = cur_rp - ring->r.rp;
 	else
@@ -1000,12 +1003,15 @@  static void rtw_pci_tx_isr(struct rtw_dev *rtwdev, struct rtw_pci *rtwpci,
 		}
 
 		if (ring->queue_stopped &&
-		    avail_desc(ring->r.wp, ring->r.rp, ring->r.len) > 4) {
+		    avail_desc(ring->r.wp, rp_idx, ring->r.len) > 4) {
 			q_map = skb_get_queue_mapping(skb);
 			ieee80211_wake_queue(hw, q_map);
 			ring->queue_stopped = false;
 		}
 
+		if (++rp_idx >= ring->r.len)
+			rp_idx = 0;
+
 		skb_pull(skb, rtwdev->chip->tx_pkt_desc_sz);
 
 		info = IEEE80211_SKB_CB(skb);