sfc: stop the TX queue before pushing new buffers

efx_enqueue_skb() can push new buffers for the xmit_more functionality.
We must stops the TX queue before this or else the TX queue does not get
restarted and we get a netdev watchdog.

In the error handling we may now need to unwind more than 1 packet, and
we may need to push the new buffers onto the partner queue.

v2: In the error leg also push this queue if xmit_more is set

Fixes: e9117e5099ea ("sfc: Firmware-Assisted TSO version 2")
Reported-by: Jarod Wilson <jarod@redhat.com>
Tested-by: Jarod Wilson <jarod@redhat.com>
Signed-off-by: Martin Habets <mhabets@solarflare.com>
Acked-by: Edward Cree <ecree@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/ethernet/sfc/tx.c b/drivers/net/ethernet/sfc/tx.c
index cece961f2e82a4e9f156828a1e6151d6e366955c..c3ad564ac4c0fe2aad3933aed8fe3efdc0bc4fe2 100644 (file)
--- a/drivers/net/ethernet/sfc/tx.c
+++ b/drivers/net/ethernet/sfc/tx.c
@@ -435,17 +435,18 @@ static int efx_tx_map_data(struct efx_tx_queue *tx_queue, struct sk_buff *skb,
        } while (1);
 }
 
-/* Remove buffers put into a tx_queue.  None of the buffers must have
- * an skb attached.
+/* Remove buffers put into a tx_queue for the current packet.
+ * None of the buffers must have an skb attached.
  */
-static void efx_enqueue_unwind(struct efx_tx_queue *tx_queue)
+static void efx_enqueue_unwind(struct efx_tx_queue *tx_queue,
+                              unsigned int insert_count)
 {
        struct efx_tx_buffer *buffer;
        unsigned int bytes_compl = 0;
        unsigned int pkts_compl = 0;
 
        /* Work backwards until we hit the original insert pointer value */
-       while (tx_queue->insert_count != tx_queue->write_count) {
+       while (tx_queue->insert_count != insert_count) {
                --tx_queue->insert_count;
                buffer = __efx_tx_queue_get_insert_buffer(tx_queue);
                efx_dequeue_buffer(tx_queue, buffer, &pkts_compl, &bytes_compl);
@@ -504,6 +505,8 @@ static int efx_tx_tso_fallback(struct efx_tx_queue *tx_queue,
  */
 netdev_tx_t efx_enqueue_skb(struct efx_tx_queue *tx_queue, struct sk_buff *skb)
 {
+       unsigned int old_insert_count = tx_queue->insert_count;
+       bool xmit_more = skb->xmit_more;
        bool data_mapped = false;
        unsigned int segments;
        unsigned int skb_len;
@@ -553,8 +556,10 @@ netdev_tx_t efx_enqueue_skb(struct efx_tx_queue *tx_queue, struct sk_buff *skb)
        /* Update BQL */
        netdev_tx_sent_queue(tx_queue->core_txq, skb_len);
 
+       efx_tx_maybe_stop_queue(tx_queue);
+
        /* Pass off to hardware */
-       if (!skb->xmit_more || netif_xmit_stopped(tx_queue->core_txq)) {
+       if (!xmit_more || netif_xmit_stopped(tx_queue->core_txq)) {
                struct efx_tx_queue *txq2 = efx_tx_queue_partner(tx_queue);
 
                /* There could be packets left on the partner queue if those
@@ -577,14 +582,26 @@ netdev_tx_t efx_enqueue_skb(struct efx_tx_queue *tx_queue, struct sk_buff *skb)
                tx_queue->tx_packets++;
        }
 
-       efx_tx_maybe_stop_queue(tx_queue);
-
        return NETDEV_TX_OK;
 
 
 err:
-       efx_enqueue_unwind(tx_queue);
+       efx_enqueue_unwind(tx_queue, old_insert_count);
        dev_kfree_skb_any(skb);
+
+       /* If we're not expecting another transmit and we had something to push
+        * on this queue or a partner queue then we need to push here to get the
+        * previous packets out.
+        */
+       if (!xmit_more) {
+               struct efx_tx_queue *txq2 = efx_tx_queue_partner(tx_queue);
+
+               if (txq2->xmit_more_available)
+                       efx_nic_push_buffers(txq2);
+
+               efx_nic_push_buffers(tx_queue);
+       }
+
        return NETDEV_TX_OK;
 }