sfc: add support for skb->xmit_more

Don't ring the doorbell, and don't do PIO.  This will also prevent
 TX Push, because there will be more than one buffer waiting when
 the doorbell is rung.

Signed-off-by: Edward Cree <ecree@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 19 insertions, 24 deletions

diff --git a/drivers/net/ethernet/sfc/tx.c b/drivers/net/ethernet/sfc/tx.c
index 320609842211..ee84a90e371c 100644
--- a/drivers/net/ethernet/sfc/tx.c
+++ b/drivers/net/ethernet/sfc/tx.c
@@ -132,15 +132,6 @@ unsigned int efx_tx_max_skb_descs(struct efx_nic *efx)
 	return max_descs;
 }
 
-/* Get partner of a TX queue, seen as part of the same net core queue */
-static struct efx_tx_queue *efx_tx_queue_partner(struct efx_tx_queue *tx_queue)
-{
-	if (tx_queue->queue & EFX_TXQ_TYPE_OFFLOAD)
-		return tx_queue - EFX_TXQ_TYPE_OFFLOAD;
-	else
-		return tx_queue + EFX_TXQ_TYPE_OFFLOAD;
-}
-
 static void efx_tx_maybe_stop_queue(struct efx_tx_queue *txq1)
 {
 	/* We need to consider both queues that the net core sees as one */
@@ -344,6 +335,7 @@ netdev_tx_t efx_enqueue_skb(struct efx_tx_queue *tx_queue, struct sk_buff *skb)
 	struct efx_nic *efx = tx_queue->efx;
 	struct device *dma_dev = &efx->pci_dev->dev;
 	struct efx_tx_buffer *buffer;
+	unsigned int old_insert_count = tx_queue->insert_count;
 	skb_frag_t *fragment;
 	unsigned int len, unmap_len = 0;
 	dma_addr_t dma_addr, unmap_addr = 0;
@@ -351,7 +343,7 @@ netdev_tx_t efx_enqueue_skb(struct efx_tx_queue *tx_queue, struct sk_buff *skb)
 	unsigned short dma_flags;
 	int i = 0;
 
-	EFX_BUG_ON_PARANOID(tx_queue->write_count != tx_queue->insert_count);
+	EFX_BUG_ON_PARANOID(tx_queue->write_count > tx_queue->insert_count);
 
 	if (skb_shinfo(skb)->gso_size)
 		return efx_enqueue_skb_tso(tx_queue, skb);
@@ -369,9 +361,8 @@ netdev_tx_t efx_enqueue_skb(struct efx_tx_queue *tx_queue, struct sk_buff *skb)
 
 	/* Consider using PIO for short packets */
 #ifdef EFX_USE_PIO
-	if (skb->len <= efx_piobuf_size && tx_queue->piobuf &&
-	    efx_nic_tx_is_empty(tx_queue) &&
-	    efx_nic_tx_is_empty(efx_tx_queue_partner(tx_queue))) {
+	if (skb->len <= efx_piobuf_size && !skb->xmit_more &&
+	    efx_nic_may_tx_pio(tx_queue)) {
 		buffer = efx_enqueue_skb_pio(tx_queue, skb);
 		dma_flags = EFX_TX_BUF_OPTION;
 		goto finish_packet;
@@ -439,13 +430,14 @@ finish_packet:
 
 	netdev_tx_sent_queue(tx_queue->core_txq, skb->len);
 
+	efx_tx_maybe_stop_queue(tx_queue);
+
 	/* Pass off to hardware */
-	efx_nic_push_buffers(tx_queue);
+	if (!skb->xmit_more || netif_xmit_stopped(tx_queue->core_txq))
+		efx_nic_push_buffers(tx_queue);
 
 	tx_queue->tx_packets++;
 
-	efx_tx_maybe_stop_queue(tx_queue);
-
 	return NETDEV_TX_OK;
 
  dma_err:
@@ -458,7 +450,7 @@ finish_packet:
 	dev_kfree_skb_any(skb);
 
 	/* Work backwards until we hit the original insert pointer value */
-	while (tx_queue->insert_count != tx_queue->write_count) {
+	while (tx_queue->insert_count != old_insert_count) {
 		unsigned int pkts_compl = 0, bytes_compl = 0;
 		--tx_queue->insert_count;
 		buffer = __efx_tx_queue_get_insert_buffer(tx_queue);
@@ -989,12 +981,13 @@ static int efx_tso_put_header(struct efx_tx_queue *tx_queue,
 /* Remove buffers put into a tx_queue.  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;
 
 	/* 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, NULL, NULL);
@@ -1258,13 +1251,14 @@ static int efx_enqueue_skb_tso(struct efx_tx_queue *tx_queue,
 			       struct sk_buff *skb)
 {
 	struct efx_nic *efx = tx_queue->efx;
+	unsigned int old_insert_count = tx_queue->insert_count;
 	int frag_i, rc;
 	struct tso_state state;
 
 	/* Find the packet protocol and sanity-check it */
 	state.protocol = efx_tso_check_protocol(skb);
 
-	EFX_BUG_ON_PARANOID(tx_queue->write_count != tx_queue->insert_count);
+	EFX_BUG_ON_PARANOID(tx_queue->write_count > tx_queue->insert_count);
 
 	rc = tso_start(&state, efx, skb);
 	if (rc)
@@ -1308,11 +1302,12 @@ static int efx_enqueue_skb_tso(struct efx_tx_queue *tx_queue,
 
 	netdev_tx_sent_queue(tx_queue->core_txq, skb->len);
 
-	/* Pass off to hardware */
-	efx_nic_push_buffers(tx_queue);
-
 	efx_tx_maybe_stop_queue(tx_queue);
 
+	/* Pass off to hardware */
+	if (!skb->xmit_more || netif_xmit_stopped(tx_queue->core_txq))
+		efx_nic_push_buffers(tx_queue);
+
 	tx_queue->tso_bursts++;
 	return NETDEV_TX_OK;
 
@@ -1336,6 +1331,6 @@ static int efx_enqueue_skb_tso(struct efx_tx_queue *tx_queue,
 		dma_unmap_single(&efx->pci_dev->dev, state.header_dma_addr,
 				 state.header_unmap_len, DMA_TO_DEVICE);
 
-	efx_enqueue_unwind(tx_queue);
+	efx_enqueue_unwind(tx_queue, old_insert_count);
 	return NETDEV_TX_OK;
 }