[PATCH] mt76: Ensure sale skb status list is processed.

[greearb@candelatech.com]

From: Ben Greear <greearb@candelatech.com>

The old code might not ever run the stale skb status processing
list, so change it to ensure the stale entries are cleaned up
regularly.

Signed-off-by: Ben Greear <greearb@candelatech.com>
---
 drivers/net/wireless/mediatek/mt76/mt76.h |  1 +
 drivers/net/wireless/mediatek/mt76/tx.c   | 24 +++++++++++++++++------
 2 files changed, 19 insertions(+), 6 deletions(-)

diff --git a/drivers/net/wireless/mediatek/mt76/mt76.h b/drivers/net/wireless/mediatek/mt76/mt76.h
index 37d82d806c09..bfb68788251f 100644
--- a/drivers/net/wireless/mediatek/mt76/mt76.h
+++ b/drivers/net/wireless/mediatek/mt76/mt76.h
@@ -271,6 +271,7 @@ struct mt76_wcid {
 
 	struct list_head list;
 	struct idr pktid;
+	unsigned long last_idr_check_at; /* in jiffies */
 };
 
 struct mt76_txq {
diff --git a/drivers/net/wireless/mediatek/mt76/tx.c b/drivers/net/wireless/mediatek/mt76/tx.c
index 938353ac272f..b6f0d74fd563 100644
--- a/drivers/net/wireless/mediatek/mt76/tx.c
+++ b/drivers/net/wireless/mediatek/mt76/tx.c
@@ -157,24 +157,35 @@ mt76_tx_status_skb_get(struct mt76_dev *dev, struct mt76_wcid *wcid, int pktid,
 		       struct sk_buff_head *list)
 {
 	struct sk_buff *skb;
+	struct sk_buff *skb2;
 	int id;
+	/* Check twice as often as the timeout value so that we mitigate
+	 * worse-case timeout detection (where we do the check right before
+	 * the per skb timer would have expired and so have to wait another interval
+	 * to detect the skb status timeout.)
+	 */
+	static const int check_interval = MT_TX_STATUS_SKB_TIMEOUT / 2;
 
 	lockdep_assert_held(&dev->status_lock);
 
 	skb = idr_remove(&wcid->pktid, pktid);
-	if (skb)
+
+	/* If we have not checked for stale entries recently,
+	 * then do that check now.
+	 */
+	if (time_is_after_jiffies(wcid->last_idr_check_at + check_interval))
 		goto out;
 
 	/* look for stale entries in the wcid idr queue */
-	idr_for_each_entry(&wcid->pktid, skb, id) {
-		struct mt76_tx_cb *cb = mt76_tx_skb_cb(skb);
+	idr_for_each_entry(&wcid->pktid, skb2, id) {
+		struct mt76_tx_cb *cb = mt76_tx_skb_cb(skb2);
 
 		if (pktid >= 0) {
 			if (!(cb->flags & MT_TX_CB_DMA_DONE))
 				continue;
 
 			if (time_is_after_jiffies(cb->jiffies +
-						   MT_TX_STATUS_SKB_TIMEOUT))
+						  MT_TX_STATUS_SKB_TIMEOUT))
 				continue;
 		}
 
@@ -182,9 +193,10 @@ mt76_tx_status_skb_get(struct mt76_dev *dev, struct mt76_wcid *wcid, int pktid,
 		 * and stop waiting for TXS callback.
 		 */
 		idr_remove(&wcid->pktid, cb->pktid);
-		__mt76_tx_status_skb_done(dev, skb, MT_TX_CB_TXS_FAILED |
-						    MT_TX_CB_TXS_DONE, list);
+		__mt76_tx_status_skb_done(dev, skb2, MT_TX_CB_TXS_FAILED |
+					  MT_TX_CB_TXS_DONE, list);
 	}
+	wcid->last_idr_check_at = jiffies;
 
 out:
 	if (idr_is_empty(&wcid->pktid))
-- 
2.20.1