dpaa2-eth: fix race condition with bql frame accounting

It might happen that Tx conf acknowledges a frame before it was
subscribed in bql, as subscribing was previously done after the enqueue
operation.

This patch moves the netdev_tx_sent_queue call before the actual frame
enqueue, so that this can never happen.

Fixes: 569dac6a5a0d ("dpaa2-eth: bql support")
Signed-off-by: Ioana Ciornei <ioana.ciornei@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 9 insertions, 4 deletions

diff --git a/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c b/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c
index 1a68052abb94..dc339dc1adb2 100644
--- a/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c
+++ b/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c
@@ -815,6 +815,14 @@ static netdev_tx_t dpaa2_eth_tx(struct sk_buff *skb, struct net_device *net_dev)
          */
         queue_mapping = skb_get_queue_mapping(skb);
         fq = &priv->fq[queue_mapping];
+
+        fd_len = dpaa2_fd_get_len(&fd);
+        nq = netdev_get_tx_queue(net_dev, queue_mapping);
+        netdev_tx_sent_queue(nq, fd_len);
+
+        /* Everything that happens after this enqueues might race with
+         * the Tx confirmation callback for this frame
+         */
         for (i = 0; i < DPAA2_ETH_ENQUEUE_RETRIES; i++) {
                 err = priv->enqueue(priv, fq, &fd, 0);
                 if (err != -EBUSY)
@@ -825,13 +833,10 @@ static netdev_tx_t dpaa2_eth_tx(struct sk_buff *skb, struct net_device *net_dev)
                 percpu_stats->tx_errors++;
                 /* Clean up everything, including freeing the skb */
                 free_tx_fd(priv, fq, &fd, false);
+                netdev_tx_completed_queue(nq, 1, fd_len);
         } else {
-                fd_len = dpaa2_fd_get_len(&fd);
                 percpu_stats->tx_packets++;
                 percpu_stats->tx_bytes += fd_len;
-
-                nq = netdev_get_tx_queue(net_dev, queue_mapping);
-                netdev_tx_sent_queue(nq, fd_len);
         }
 
         return NETDEV_TX_OK;