mt7601u: lock out rx path and tx status reporting

mac80211 requires that rx path does not run concurrently with
tx status reporting.  Add a spinlock which will ensure that.
Signed-off-by: Jakub Kicinski <kubakici@wp.pl>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

drivers/net/wireless/mediatek/mt7601u/dma.c

@@ -112,7 +112,9 @@ static void mt7601u_rx_process_seg(struct mt7601u_dev *dev, u8 *data,
 	if (!skb)
 		return;
 
+	spin_lock(&dev->mac_lock);
 	ieee80211_rx(dev->hw, skb);
+	spin_unlock(&dev->mac_lock);
 }
 
 static u16 mt7601u_rx_next_seg_len(u8 *data, u32 data_len)

drivers/net/wireless/mediatek/mt7601u/init.c

@@ -454,6 +454,7 @@ struct mt7601u_dev *mt7601u_alloc_device(struct device *pdev)
 	spin_lock_init(&dev->tx_lock);
 	spin_lock_init(&dev->rx_lock);
 	spin_lock_init(&dev->lock);
+	spin_lock_init(&dev->mac_lock);
 	spin_lock_init(&dev->con_mon_lock);
 	atomic_set(&dev->avg_ampdu_len, 1);
 	skb_queue_head_init(&dev->tx_skb_done);

drivers/net/wireless/mediatek/mt7601u/mac.c

@@ -182,9 +182,9 @@ void mt76_send_tx_status(struct mt7601u_dev *dev, struct mt76_tx_status *stat)
 
 	mt76_mac_fill_tx_status(dev, &info, stat);
 
-	local_bh_disable();
+	spin_lock_bh(&dev->mac_lock);
 	ieee80211_tx_status_noskb(dev->hw, sta, &info);
-	local_bh_enable();
+	spin_unlock_bh(&dev->mac_lock);
 
 	rcu_read_unlock();
 }

drivers/net/wireless/mediatek/mt7601u/mt7601u.h

@@ -141,8 +141,9 @@ enum {
 /**
  * struct mt7601u_dev - adapter structure
  * @lock:		protects @wcid->tx_rate.
+ * @mac_lock:		locks out mac80211's tx status and rx paths.
  * @tx_lock:		protects @tx_q and changes of MT7601U_STATE_*_STATS
-			flags in @state.
+ *			flags in @state.
  * @rx_lock:		protects @rx_q.
  * @con_mon_lock:	protects @ap_bssid, @bcn_*, @avg_rssi.
  * @mutex:		ensures exclusive access from mac80211 callbacks.
@@ -177,6 +178,7 @@ struct mt7601u_dev {
 	struct mt76_wcid __rcu *wcid[N_WCIDS];
 
 	spinlock_t lock;
+	spinlock_t mac_lock;
 
 	const u16 *beacon_offsets;
 

drivers/net/wireless/mediatek/mt7601u/tx.c

@@ -116,7 +116,10 @@ void mt7601u_tx_status(struct mt7601u_dev *dev, struct sk_buff *skb)
 	ieee80211_tx_info_clear_status(info);
 	info->status.rates[0].idx = -1;
 	info->flags |= IEEE80211_TX_STAT_ACK;
+
+	spin_lock(&dev->mac_lock);
 	ieee80211_tx_status(dev->hw, skb);
+	spin_unlock(&dev->mac_lock);
 }
 
 static int mt7601u_skb_rooms(struct mt7601u_dev *dev, struct sk_buff *skb)