[PATCH net-next v3 1/8] net: bcmgenet: ring the doorbell when the last frame of a batch is dropped

[Nicolai Buchwitz]

bcmgenet_xmit() only writes the producer index at the end of a batch. The
error exits return before that write. If the dropped frame was the last of
an xmit_more batch, the frames queued before it stay in the ring until the
next transmit. The queue is still running, so the watchdog does not fire.

Write the producer index on those exits too.

Fixes: ddd0ca5d60b3 ("net: bcmgenet: add support for xmit_more")
Signed-off-by: Nicolai Buchwitz <nb@xxxxxxxxxxx>
---
 drivers/net/ethernet/broadcom/genet/bcmgenet.c | 25 ++++++++++++++++---------
 1 file changed, 16 insertions(+), 9 deletions(-)

diff --git a/drivers/net/ethernet/broadcom/genet/bcmgenet.c b/drivers/net/ethernet/broadcom/genet/bcmgenet.c
index 4c9db2f9fc25..06ec8c211dd7 100644
--- a/drivers/net/ethernet/broadcom/genet/bcmgenet.c
+++ b/drivers/net/ethernet/broadcom/genet/bcmgenet.c
@@ -2119,6 +2119,15 @@ static void bcmgenet_hide_tsb(struct sk_buff *skb)
 	__skb_pull(skb, sizeof(struct status_64));
 }
 
+static void bcmgenet_tx_kick(struct bcmgenet_priv *priv,
+			     struct bcmgenet_tx_ring *ring,
+			     struct netdev_queue *txq)
+{
+	if (!netdev_xmit_more() || netif_xmit_stopped(txq))
+		bcmgenet_tdma_ring_writel(priv, ring->index,
+					  ring->prod_index, TDMA_PROD_INDEX);
+}
+
 static netdev_tx_t bcmgenet_xmit(struct sk_buff *skb, struct net_device *dev)
 {
 	struct bcmgenet_priv *priv = netdev_priv(dev);
@@ -2155,10 +2164,8 @@ static netdev_tx_t bcmgenet_xmit(struct sk_buff *skb, struct net_device *dev)
 
 	/* add the Transmit Status Block */
 	skb = bcmgenet_add_tsb(dev, skb, ring);
-	if (!skb) {
-		ret = NETDEV_TX_OK;
-		goto out;
-	}
+	if (!skb)
+		goto drop;
 
 	for (i = 0; i <= nr_frags; i++) {
 		tx_cb_ptr = bcmgenet_get_txcb(priv, ring);
@@ -2183,7 +2190,6 @@ static netdev_tx_t bcmgenet_xmit(struct sk_buff *skb, struct net_device *dev)
 		if (ret) {
 			priv->mib.tx_dma_failed++;
 			netif_err(priv, tx_err, dev, "Tx DMA map failed\n");
-			ret = NETDEV_TX_OK;
 			goto out_unmap_frags;
 		}
 		dma_unmap_addr_set(tx_cb_ptr, dma_addr, mapping);
@@ -2225,10 +2231,7 @@ static netdev_tx_t bcmgenet_xmit(struct sk_buff *skb, struct net_device *dev)
 	if (ring->free_bds <= (MAX_SKB_FRAGS + 1))
 		netif_tx_stop_queue(txq);
 
-	if (!netdev_xmit_more() || netif_xmit_stopped(txq))
-		/* Packets are ready, update producer index */
-		bcmgenet_tdma_ring_writel(priv, ring->index,
-					  ring->prod_index, TDMA_PROD_INDEX);
+	bcmgenet_tx_kick(priv, ring, txq);
 out:
 	spin_unlock(&ring->lock);
 
@@ -2245,6 +2248,10 @@ static netdev_tx_t bcmgenet_xmit(struct sk_buff *skb, struct net_device *dev)
 	}
 
 	dev_kfree_skb(skb);
+drop:
+	/* The dropped frame may have been the last one of the batch */
+	bcmgenet_tx_kick(priv, ring, txq);
+	ret = NETDEV_TX_OK;
 	goto out;
 }
 

-- 
2.53.0