[PATCH 1/4] mt76: add missing locking around ampdu action

[PATCH 1/4] mt76: add missing locking around ampdu action

[Felix Fietkau]

This is needed primarily to avoid races in dealing with rx aggregation
related data structures

Signed-off-by: Felix Fietkau <nbd@nbd.name>
---
 drivers/net/wireless/mediatek/mt76/mt7603/main.c  | 2 ++
 drivers/net/wireless/mediatek/mt76/mt7615/main.c  | 2 ++
 drivers/net/wireless/mediatek/mt76/mt76x02_util.c | 2 ++
 3 files changed, 6 insertions(+)

diff --git a/drivers/net/wireless/mediatek/mt76/mt7603/main.c b/drivers/net/wireless/mediatek/mt76/mt7603/main.c
index 180eb6bb781a..c4dac556fb2e 100644
--- a/drivers/net/wireless/mediatek/mt76/mt7603/main.c
+++ b/drivers/net/wireless/mediatek/mt76/mt7603/main.c
@@ -569,6 +569,7 @@ mt7603_ampdu_action(struct ieee80211_hw *hw, struct ieee80211_vif *vif,
 
 	mtxq = (struct mt76_txq *)txq->drv_priv;
 
+	mutex_lock(&dev->mt76.mutex);
 	switch (action) {
 	case IEEE80211_AMPDU_RX_START:
 		mt76_rx_aggr_start(&dev->mt76, &msta->wcid, tid, ssn,
@@ -598,6 +599,7 @@ mt7603_ampdu_action(struct ieee80211_hw *hw, struct ieee80211_vif *vif,
 		ieee80211_stop_tx_ba_cb_irqsafe(vif, sta->addr, tid);
 		break;
 	}
+	mutex_unlock(&dev->mt76.mutex);
 
 	return 0;
 }
diff --git a/drivers/net/wireless/mediatek/mt76/mt7615/main.c b/drivers/net/wireless/mediatek/mt76/mt7615/main.c
index 942076b6d1ad..d9f4d425424c 100644
--- a/drivers/net/wireless/mediatek/mt76/mt7615/main.c
+++ b/drivers/net/wireless/mediatek/mt76/mt7615/main.c
@@ -483,6 +483,7 @@ mt7615_ampdu_action(struct ieee80211_hw *hw, struct ieee80211_vif *vif,
 
 	mtxq = (struct mt76_txq *)txq->drv_priv;
 
+	mutex_lock(&dev->mt76.mutex);
 	switch (action) {
 	case IEEE80211_AMPDU_RX_START:
 		mt76_rx_aggr_start(&dev->mt76, &msta->wcid, tid, ssn,
@@ -513,6 +514,7 @@ mt7615_ampdu_action(struct ieee80211_hw *hw, struct ieee80211_vif *vif,
 		ieee80211_stop_tx_ba_cb_irqsafe(vif, sta->addr, tid);
 		break;
 	}
+	mutex_unlock(&dev->mt76.mutex);
 
 	return 0;
 }
diff --git a/drivers/net/wireless/mediatek/mt76/mt76x02_util.c b/drivers/net/wireless/mediatek/mt76/mt76x02_util.c
index f5695ebdb225..bb7edf288597 100644
--- a/drivers/net/wireless/mediatek/mt76/mt76x02_util.c
+++ b/drivers/net/wireless/mediatek/mt76/mt76x02_util.c
@@ -372,6 +372,7 @@ int mt76x02_ampdu_action(struct ieee80211_hw *hw, struct ieee80211_vif *vif,
 
 	mtxq = (struct mt76_txq *)txq->drv_priv;
 
+	mutex_lock(&dev->mt76.mutex);
 	switch (action) {
 	case IEEE80211_AMPDU_RX_START:
 		mt76_rx_aggr_start(&dev->mt76, &msta->wcid, tid,
@@ -401,6 +402,7 @@ int mt76x02_ampdu_action(struct ieee80211_hw *hw, struct ieee80211_vif *vif,
 		ieee80211_stop_tx_ba_cb_irqsafe(vif, sta->addr, tid);
 		break;
 	}
+	mutex_unlock(&dev->mt76.mutex);
 
 	return 0;
 }
-- 
2.17.0

[PATCH 2/4] mt76: drop rcu read lock in mt76_rx_aggr_stop

[Felix Fietkau]

A rcu read locked section is not allowed to sleep, and the rcu lock here
isn't actually necessary, because we're holding dev->mutex.
Fixes an issue when the tid work item is still running while freeing
a station or stopping the aggregation session

Signed-off-by: Felix Fietkau <nbd@nbd.name>
---
 drivers/net/wireless/mediatek/mt76/agg-rx.c | 10 +++-------
 1 file changed, 3 insertions(+), 7 deletions(-)

diff --git a/drivers/net/wireless/mediatek/mt76/agg-rx.c b/drivers/net/wireless/mediatek/mt76/agg-rx.c
index 2276fd4e9ec3..b05d439dca3b 100644
--- a/drivers/net/wireless/mediatek/mt76/agg-rx.c
+++ b/drivers/net/wireless/mediatek/mt76/agg-rx.c
@@ -277,17 +277,13 @@ static void mt76_rx_aggr_shutdown(struct mt76_dev *dev, struct mt76_rx_tid *tid)
 
 void mt76_rx_aggr_stop(struct mt76_dev *dev, struct mt76_wcid *wcid, u8 tidno)
 {
-	struct mt76_rx_tid *tid;
-
-	rcu_read_lock();
+	struct mt76_rx_tid *tid = NULL;
 
-	tid = rcu_dereference(wcid->aggr[tidno]);
+	rcu_swap_protected(wcid->aggr[tidno], tid,
+			   lockdep_is_held(&dev->mutex));
 	if (tid) {
-		rcu_assign_pointer(wcid->aggr[tidno], NULL);
 		mt76_rx_aggr_shutdown(dev, tid);
 		kfree_rcu(tid, rcu_head);
 	}
-
-	rcu_read_unlock();
 }
 EXPORT_SYMBOL_GPL(mt76_rx_aggr_stop);
-- 
2.17.0

[PATCH 3/4] mt76: fix aggregation stop issue

[Felix Fietkau]

Cancel the workqueue after the tid has been cleaned up, in order to
avoid a possible rescheduling from within the work function.

Signed-off-by: Felix Fietkau <nbd@nbd.name>
---
 drivers/net/wireless/mediatek/mt76/agg-rx.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/net/wireless/mediatek/mt76/agg-rx.c b/drivers/net/wireless/mediatek/mt76/agg-rx.c
index b05d439dca3b..53b5a4b2dcc5 100644
--- a/drivers/net/wireless/mediatek/mt76/agg-rx.c
+++ b/drivers/net/wireless/mediatek/mt76/agg-rx.c
@@ -130,8 +130,10 @@ mt76_rx_aggr_check_ctl(struct sk_buff *skb, struct sk_buff_head *frames)
 		return;
 
 	spin_lock_bh(&tid->lock);
-	mt76_rx_aggr_release_frames(tid, frames, seqno);
-	mt76_rx_aggr_release_head(tid, frames);
+	if (!tid->stopped) {
+		mt76_rx_aggr_release_frames(tid, frames, seqno);
+		mt76_rx_aggr_release_head(tid, frames);
+	}
 	spin_unlock_bh(&tid->lock);
 }
 
@@ -257,8 +259,6 @@ static void mt76_rx_aggr_shutdown(struct mt76_dev *dev, struct mt76_rx_tid *tid)
 	u8 size = tid->size;
 	int i;
 
-	cancel_delayed_work_sync(&tid->reorder_work);
-
 	spin_lock_bh(&tid->lock);
 
 	tid->stopped = true;
@@ -273,6 +273,8 @@ static void mt76_rx_aggr_shutdown(struct mt76_dev *dev, struct mt76_rx_tid *tid)
 	}
 
 	spin_unlock_bh(&tid->lock);
+
+	cancel_delayed_work_sync(&tid->reorder_work);
 }
 
 void mt76_rx_aggr_stop(struct mt76_dev *dev, struct mt76_wcid *wcid, u8 tidno)
-- 
2.17.0

[PATCH 4/4] mt76: avoid enabling interrupt if NAPI poll is still pending

[Felix Fietkau]

if napi_complete() returns false, it means that polling is still pending.
Interrupts should not fire until the polling is no longer scheduled

Signed-off-by: Felix Fietkau <nbd@nbd.name>
---
 drivers/net/wireless/mediatek/mt76/dma.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/net/wireless/mediatek/mt76/dma.c b/drivers/net/wireless/mediatek/mt76/dma.c
index e2ce59b260c1..4da7cffbab29 100644
--- a/drivers/net/wireless/mediatek/mt76/dma.c
+++ b/drivers/net/wireless/mediatek/mt76/dma.c
@@ -537,10 +537,8 @@ mt76_dma_rx_poll(struct napi_struct *napi, int budget)
 
 	rcu_read_unlock();
 
-	if (done < budget) {
-		napi_complete(napi);
+	if (done < budget && napi_complete(napi))
 		dev->drv->rx_poll_complete(dev, qid);
-	}
 
 	return done;
 }
-- 
2.17.0