mt76: mt7915: fix possible deadlock in mt7915_stop

make mac_work per phy instead of per device and fix a possible deadlock
in mt7915_stop since mt7915_mac_work runs holding mt76 mutex
Signed-off-by: Ryder Lee <ryder.lee@mediatek.com>
Signed-off-by: Felix Fietkau <nbd@nbd.name>

drivers/net/wireless/mediatek/mt76/mt7915/init.c

@@ -592,6 +592,7 @@ int mt7915_register_ext_phy(struct mt7915_dev *dev)
 	if (phy)
 		return 0;
 
+	INIT_DELAYED_WORK(&phy->mac_work, mt7915_mac_work);
 	mt7915_cap_dbdc_enable(dev);
 	mphy = mt76_alloc_phy(&dev->mt76, sizeof(*phy), &mt7915_ops);
 	if (!mphy)
@@ -642,7 +643,7 @@ int mt7915_register_device(struct mt7915_dev *dev)
 	dev->phy.dev = dev;
 	dev->phy.mt76 = &dev->mt76.phy;
 	dev->mt76.phy.priv = &dev->phy;
-	INIT_DELAYED_WORK(&dev->mt76.mac_work, mt7915_mac_work);
+	INIT_DELAYED_WORK(&dev->phy.mac_work, mt7915_mac_work);
 	INIT_LIST_HEAD(&dev->sta_poll_list);
 	spin_lock_init(&dev->sta_poll_lock);
 

drivers/net/wireless/mediatek/mt76/mt7915/mac.c

@@ -1156,26 +1156,32 @@ mt7915_dma_reset(struct mt7915_dev *dev)
 /* system error recovery */
 void mt7915_mac_reset_work(struct work_struct *work)
 {
+	struct mt7915_phy *phy2;
+	struct mt76_phy *ext_phy;
 	struct mt7915_dev *dev;
 
 	dev = container_of(work, struct mt7915_dev, reset_work);
+	ext_phy = dev->mt76.phy2;
+	phy2 = ext_phy ? ext_phy->priv : NULL;
 
 	if (!(READ_ONCE(dev->reset_state) & MT_MCU_CMD_STOP_DMA))
 		return;
 
 	ieee80211_stop_queues(mt76_hw(dev));
-	if (dev->mt76.phy2)
-		ieee80211_stop_queues(dev->mt76.phy2->hw);
+	if (ext_phy)
+		ieee80211_stop_queues(ext_phy->hw);
 
 	set_bit(MT76_RESET, &dev->mphy.state);
 	set_bit(MT76_MCU_RESET, &dev->mphy.state);
 	wake_up(&dev->mt76.mcu.wait);
-	cancel_delayed_work_sync(&dev->mt76.mac_work);
+	cancel_delayed_work_sync(&dev->phy.mac_work);
+	if (phy2)
+		cancel_delayed_work_sync(&phy2->mac_work);
 
 	/* lock/unlock all queues to ensure that no tx is pending */
 	mt76_txq_schedule_all(&dev->mphy);
-	if (dev->mt76.phy2)
-		mt76_txq_schedule_all(dev->mt76.phy2);
+	if (ext_phy)
+		mt76_txq_schedule_all(ext_phy);
 
 	tasklet_disable(&dev->mt76.tx_tasklet);
 	napi_disable(&dev->mt76.napi[0]);
@@ -1211,8 +1217,8 @@ void mt7915_mac_reset_work(struct work_struct *work)
 	napi_schedule(&dev->mt76.napi[2]);
 
 	ieee80211_wake_queues(mt76_hw(dev));
-	if (dev->mt76.phy2)
-		ieee80211_wake_queues(dev->mt76.phy2->hw);
+	if (ext_phy)
+		ieee80211_wake_queues(ext_phy->hw);
 
 	mt76_wr(dev, MT_MCU_INT_EVENT, MT_MCU_INT_EVENT_RESET_DONE);
 	mt7915_wait_reset_state(dev, MT_MCU_CMD_NORMAL_STATE);
@@ -1221,7 +1227,10 @@ void mt7915_mac_reset_work(struct work_struct *work)
 
 	mt7915_update_beacons(dev);
 
-	ieee80211_queue_delayed_work(mt76_hw(dev), &dev->mt76.mac_work,
+	ieee80211_queue_delayed_work(mt76_hw(dev), &dev->phy.mac_work,
+				     MT7915_WATCHDOG_TIME);
+	if (phy2)
+		ieee80211_queue_delayed_work(ext_phy->hw, &phy2->mac_work,
 					     MT7915_WATCHDOG_TIME);
 }
 
@@ -1307,25 +1316,25 @@ void mt7915_mac_sta_stats_work(struct work_struct *work)
 
 void mt7915_mac_work(struct work_struct *work)
 {
-	struct mt7915_dev *dev;
+	struct mt7915_phy *phy;
+	struct mt76_dev *mdev;
 
-	dev = (struct mt7915_dev *)container_of(work, struct mt76_dev,
+	phy = (struct mt7915_phy *)container_of(work, struct mt7915_phy,
 						mac_work.work);
+	mdev = &phy->dev->mt76;
 
-	mutex_lock(&dev->mt76.mutex);
-	mt76_update_survey(&dev->mt76);
-	if (++dev->mac_work_count == 5) {
-		struct mt7915_phy *ext_phy = mt7915_ext_phy(dev);
+	mutex_lock(&mdev->mutex);
 
-		mt7915_mac_update_mib_stats(&dev->phy);
-		if (ext_phy)
-			mt7915_mac_update_mib_stats(ext_phy);
+	mt76_update_survey(mdev);
+	if (++phy->mac_work_count == 5) {
+		phy->mac_work_count = 0;
 
-		dev->mac_work_count = 0;
+		mt7915_mac_update_mib_stats(phy);
 	}
-	mutex_unlock(&dev->mt76.mutex);
 
-	ieee80211_queue_delayed_work(mt76_hw(dev), &dev->mt76.mac_work,
+	mutex_unlock(&mdev->mutex);
+
+	ieee80211_queue_delayed_work(phy->mt76->hw, &phy->mac_work,
 				     MT7915_WATCHDOG_TIME);
 }
 

drivers/net/wireless/mediatek/mt76/mt7915/main.c

@@ -47,14 +47,12 @@ static int mt7915_start(struct ieee80211_hw *hw)
 
 	set_bit(MT76_STATE_RUNNING, &phy->mt76->state);
 
-	if (running)
-		goto out;
+	ieee80211_queue_delayed_work(hw, &phy->mac_work,
+				     MT7915_WATCHDOG_TIME);
 
+	if (!running)
 		mt7915_mac_reset_counters(phy);
 
-	ieee80211_queue_delayed_work(mt76_hw(dev), &dev->mt76.mac_work,
-				     MT7915_WATCHDOG_TIME);
-out:
 	mutex_unlock(&dev->mt76.mutex);
 
 	return 0;
@@ -65,6 +63,8 @@ static void mt7915_stop(struct ieee80211_hw *hw)
 	struct mt7915_dev *dev = mt7915_hw_dev(hw);
 	struct mt7915_phy *phy = mt7915_hw_phy(hw);
 
+	cancel_delayed_work_sync(&phy->mac_work);
+
 	mutex_lock(&dev->mt76.mutex);
 
 	clear_bit(MT76_STATE_RUNNING, &phy->mt76->state);
@@ -75,8 +75,6 @@ static void mt7915_stop(struct ieee80211_hw *hw)
 	}
 
 	if (!mt7915_dev_running(dev)) {
-		cancel_delayed_work_sync(&dev->mt76.mac_work);
-
 		mt7915_mcu_set_pm(dev, 0, 1);
 		mt7915_mcu_set_mac(dev, 0, false, false);
 	}
@@ -230,7 +228,7 @@ static int mt7915_set_channel(struct mt7915_phy *phy)
 	struct mt7915_dev *dev = phy->dev;
 	int ret;
 
-	cancel_delayed_work_sync(&dev->mt76.mac_work);
+	cancel_delayed_work_sync(&phy->mac_work);
 
 	mutex_lock(&dev->mt76.mutex);
 	set_bit(MT76_RESET, &phy->mt76->state);
@@ -254,7 +252,7 @@ static int mt7915_set_channel(struct mt7915_phy *phy)
 	mutex_unlock(&dev->mt76.mutex);
 
 	mt76_txq_schedule_all(phy->mt76);
-	ieee80211_queue_delayed_work(mt76_hw(dev), &dev->mt76.mac_work,
+	ieee80211_queue_delayed_work(phy->mt76->hw, &phy->mac_work,
 				     MT7915_WATCHDOG_TIME);
 
 	return ret;

drivers/net/wireless/mediatek/mt76/mt7915/mt7915.h

@@ -141,6 +141,9 @@ struct mt7915_phy {
 	u32 ampdu_ref;
 
 	struct mib_stats mib;
+
+	struct delayed_work mac_work;
+	u8 mac_work_count;
 };
 
 struct mt7915_dev {
@@ -168,7 +171,6 @@ struct mt7915_dev {
 
 	s8 **rate_power; /* TODO: use mt76_rate_power */
 
-	u8 mac_work_count;
 	bool fw_debug;
 };