wifi: mt76: fix race condition related to checking tx queue fill status

When drv_tx calls race against local tx scheduling, the queue fill status checks
can potentially race, leading to dma queue entries being overwritten.
Fix this by deferring packets from drv_tx calls to the tx worker, in order to
ensure that all regular queue tx comes from the same context.

Reported-by: Ryder Lee <Ryder.Lee@mediatek.com>
Signed-off-by: Felix Fietkau <nbd@nbd.name>

1 files changed, 48 insertions, 2 deletions

diff --git a/drivers/net/wireless/mediatek/mt76/mac80211.c b/drivers/net/wireless/mediatek/mt76/mac80211.c
index db24634e4a08..8cd1a7ed82f4 100644
--- a/drivers/net/wireless/mediatek/mt76/mac80211.c
+++ b/drivers/net/wireless/mediatek/mt76/mac80211.c
@@ -415,6 +415,9 @@ mt76_phy_init(struct mt76_phy *phy, struct ieee80211_hw *hw)
 	struct mt76_dev *dev = phy->dev;
 	struct wiphy *wiphy = hw->wiphy;
 
+	INIT_LIST_HEAD(&phy->tx_list);
+	spin_lock_init(&phy->tx_lock);
+
 	SET_IEEE80211_DEV(hw, dev->dev);
 	SET_IEEE80211_PERM_ADDR(hw, phy->macaddr);
 
@@ -689,6 +692,7 @@ int mt76_register_device(struct mt76_dev *dev, bool vht,
 	int ret;
 
 	dev_set_drvdata(dev->dev, dev);
+	mt76_wcid_init(&dev->global_wcid);
 	ret = mt76_phy_init(phy, hw);
 	if (ret)
 		return ret;
@@ -744,6 +748,7 @@ void mt76_unregister_device(struct mt76_dev *dev)
 	if (IS_ENABLED(CONFIG_MT76_LEDS))
 		mt76_led_cleanup(&dev->phy);
 	mt76_tx_status_check(dev, true);
+	mt76_wcid_cleanup(dev, &dev->global_wcid);
 	ieee80211_unregister_hw(hw);
 }
 EXPORT_SYMBOL_GPL(mt76_unregister_device);
@@ -1412,7 +1417,7 @@ mt76_sta_add(struct mt76_phy *phy, struct ieee80211_vif *vif,
 	wcid->phy_idx = phy->band_idx;
 	rcu_assign_pointer(dev->wcid[wcid->idx], wcid);
 
-	mt76_packet_id_init(wcid);
+	mt76_wcid_init(wcid);
 out:
 	mutex_unlock(&dev->mutex);
 
@@ -1431,7 +1436,7 @@ void __mt76_sta_remove(struct mt76_dev *dev, struct ieee80211_vif *vif,
 	if (dev->drv->sta_remove)
 		dev->drv->sta_remove(dev, vif, sta);
 
-	mt76_packet_id_flush(dev, wcid);
+	mt76_wcid_cleanup(dev, wcid);
 
 	mt76_wcid_mask_clear(dev->wcid_mask, idx);
 	mt76_wcid_mask_clear(dev->wcid_phy_mask, idx);
@@ -1487,6 +1492,47 @@ void mt76_sta_pre_rcu_remove(struct ieee80211_hw *hw, struct ieee80211_vif *vif,
 }
 EXPORT_SYMBOL_GPL(mt76_sta_pre_rcu_remove);
 
+void mt76_wcid_init(struct mt76_wcid *wcid)
+{
+	INIT_LIST_HEAD(&wcid->tx_list);
+	skb_queue_head_init(&wcid->tx_pending);
+
+	INIT_LIST_HEAD(&wcid->list);
+	idr_init(&wcid->pktid);
+}
+EXPORT_SYMBOL_GPL(mt76_wcid_init);
+
+void mt76_wcid_cleanup(struct mt76_dev *dev, struct mt76_wcid *wcid)
+{
+	struct mt76_phy *phy = dev->phys[wcid->phy_idx];
+	struct ieee80211_hw *hw;
+	struct sk_buff_head list;
+	struct sk_buff *skb;
+
+	mt76_tx_status_lock(dev, &list);
+	mt76_tx_status_skb_get(dev, wcid, -1, &list);
+	mt76_tx_status_unlock(dev, &list);
+
+	idr_destroy(&wcid->pktid);
+
+	spin_lock_bh(&phy->tx_lock);
+
+	if (!list_empty(&wcid->tx_list))
+		list_del_init(&wcid->tx_list);
+
+	spin_lock(&wcid->tx_pending.lock);
+	skb_queue_splice_tail_init(&wcid->tx_pending, &list);
+	spin_unlock(&wcid->tx_pending.lock);
+
+	spin_unlock_bh(&phy->tx_lock);
+
+	while ((skb = __skb_dequeue(&list)) != NULL) {
+		hw = mt76_tx_status_get_hw(dev, skb);
+		ieee80211_free_txskb(hw, skb);
+	}
+}
+EXPORT_SYMBOL_GPL(mt76_wcid_cleanup);
+
 int mt76_get_txpower(struct ieee80211_hw *hw, struct ieee80211_vif *vif,
 		     int *dbm)
 {