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: 6147aa64fd23 ("dpaa2-eth: bql support")
Signed-off-by: Ioana Ciornei <ioana.ciornei@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c b/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c
index 1a68052abb94a00d39bf2d35d89f20fc80d6af9c..dc339dc1adb21c30224fbce6eb0d60fd861c9388 100644 (file)
--- 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;