i40e: skb->xmit_more support

Support skb->xmit_more in i40e is straightforward : we need to move
around i40e_maybe_stop_tx() call to correctly test netif_xmit_stopped()
before taking the decision to not kick the NIC.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Acked-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/ethernet/intel/i40e/i40e_txrx.c b/drivers/net/ethernet/intel/i40e/i40e_txrx.c
index 267992b..3195d82 100644 (file)
--- a/drivers/net/ethernet/intel/i40e/i40e_txrx.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_txrx.c
@@ -2053,6 +2053,47 @@ static void i40e_create_tx_ctx(struct i40e_ring *tx_ring,
 }
 
 /**
+ * __i40e_maybe_stop_tx - 2nd level check for tx stop conditions
+ * @tx_ring: the ring to be checked
+ * @size:    the size buffer we want to assure is available
+ *
+ * Returns -EBUSY if a stop is needed, else 0
+ **/
+static inline int __i40e_maybe_stop_tx(struct i40e_ring *tx_ring, int size)
+{
+       netif_stop_subqueue(tx_ring->netdev, tx_ring->queue_index);
+       /* Memory barrier before checking head and tail */
+       smp_mb();
+
+       /* Check again in a case another CPU has just made room available. */
+       if (likely(I40E_DESC_UNUSED(tx_ring) < size))
+               return -EBUSY;
+
+       /* A reprieve! - use start_queue because it doesn't call schedule */
+       netif_start_subqueue(tx_ring->netdev, tx_ring->queue_index);
+       ++tx_ring->tx_stats.restart_queue;
+       return 0;
+}
+
+/**
+ * i40e_maybe_stop_tx - 1st level check for tx stop conditions
+ * @tx_ring: the ring to be checked
+ * @size:    the size buffer we want to assure is available
+ *
+ * Returns 0 if stop is not needed
+ **/
+#ifdef I40E_FCOE
+int i40e_maybe_stop_tx(struct i40e_ring *tx_ring, int size)
+#else
+static int i40e_maybe_stop_tx(struct i40e_ring *tx_ring, int size)
+#endif
+{
+       if (likely(I40E_DESC_UNUSED(tx_ring) >= size))
+               return 0;
+       return __i40e_maybe_stop_tx(tx_ring, size);
+}
+
+/**
  * i40e_tx_map - Build the Tx descriptor
  * @tx_ring:  ring to send buffer on
  * @skb:      send buffer
@@ -2195,8 +2236,12 @@ static void i40e_tx_map(struct i40e_ring *tx_ring, struct sk_buff *skb,
 
        tx_ring->next_to_use = i;
 
+       i40e_maybe_stop_tx(tx_ring, DESC_NEEDED);
        /* notify HW of packet */
-       writel(i, tx_ring->tail);
+       if (!skb->xmit_more ||
+           netif_xmit_stopped(netdev_get_tx_queue(tx_ring->netdev,
+                                                  tx_ring->queue_index)))
+               writel(i, tx_ring->tail);
 
        return;
 
@@ -2218,47 +2263,6 @@ dma_error:
 }
 
 /**
- * __i40e_maybe_stop_tx - 2nd level check for tx stop conditions
- * @tx_ring: the ring to be checked
- * @size:    the size buffer we want to assure is available
- *
- * Returns -EBUSY if a stop is needed, else 0
- **/
-static inline int __i40e_maybe_stop_tx(struct i40e_ring *tx_ring, int size)
-{
-       netif_stop_subqueue(tx_ring->netdev, tx_ring->queue_index);
-       /* Memory barrier before checking head and tail */
-       smp_mb();
-
-       /* Check again in a case another CPU has just made room available. */
-       if (likely(I40E_DESC_UNUSED(tx_ring) < size))
-               return -EBUSY;
-
-       /* A reprieve! - use start_queue because it doesn't call schedule */
-       netif_start_subqueue(tx_ring->netdev, tx_ring->queue_index);
-       ++tx_ring->tx_stats.restart_queue;
-       return 0;
-}
-
-/**
- * i40e_maybe_stop_tx - 1st level check for tx stop conditions
- * @tx_ring: the ring to be checked
- * @size:    the size buffer we want to assure is available
- *
- * Returns 0 if stop is not needed
- **/
-#ifdef I40E_FCOE
-int i40e_maybe_stop_tx(struct i40e_ring *tx_ring, int size)
-#else
-static int i40e_maybe_stop_tx(struct i40e_ring *tx_ring, int size)
-#endif
-{
-       if (likely(I40E_DESC_UNUSED(tx_ring) >= size))
-               return 0;
-       return __i40e_maybe_stop_tx(tx_ring, size);
-}
-
-/**
  * i40e_xmit_descriptor_count - calculate number of tx descriptors needed
  * @skb:     send buffer
  * @tx_ring: ring to send buffer on
@@ -2372,8 +2376,6 @@ static netdev_tx_t i40e_xmit_frame_ring(struct sk_buff *skb,
        i40e_tx_map(tx_ring, skb, first, tx_flags, hdr_len,
                    td_cmd, td_offset);
 
-       i40e_maybe_stop_tx(tx_ring, DESC_NEEDED);
-
        return NETDEV_TX_OK;
 
 out_drop: