igb: Add support for byte queue limits.

This adds support for byte queue limits (BQL)

Since this driver collects bytes count in 'bytecount' field, use it also
in igb_tx_map()

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
CC: Alexander Duyck <alexander.h.duyck@intel.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/intel/igb/igb.h

@@ -447,4 +447,9 @@ static inline s32 igb_get_phy_info(struct e1000_hw *hw)
 	return 0;
 }
 
+static inline struct netdev_queue *txring_txq(const struct igb_ring *tx_ring)
+{
+	return netdev_get_tx_queue(tx_ring->netdev, tx_ring->queue_index);
+}
+
 #endif /* _IGB_H_ */

drivers/net/ethernet/intel/igb/igb_main.c

@@ -3201,6 +3201,7 @@ static void igb_clean_tx_ring(struct igb_ring *tx_ring)
 		buffer_info = &tx_ring->tx_buffer_info[i];
 		igb_unmap_and_free_tx_resource(tx_ring, buffer_info);
 	}
+	netdev_tx_reset_queue(txring_txq(tx_ring));
 
 	size = sizeof(struct igb_tx_buffer) * tx_ring->count;
 	memset(tx_ring->tx_buffer_info, 0, size);
@@ -4238,6 +4239,8 @@ static void igb_tx_map(struct igb_ring *tx_ring,
 		frag++;
 	}
 
+	netdev_tx_sent_queue(txring_txq(tx_ring), first->bytecount);
+
 	/* write last descriptor with RS and EOP bits */
 	cmd_type |= cpu_to_le32(size) | cpu_to_le32(IGB_TXD_DCMD);
 	tx_desc->read.cmd_type_len = cmd_type;
@@ -5777,6 +5780,8 @@ static bool igb_clean_tx_irq(struct igb_q_vector *q_vector)
 		}
 	}
 
+	netdev_tx_completed_queue(txring_txq(tx_ring),
+				  total_packets, total_bytes);
 	i += tx_ring->count;
 	tx_ring->next_to_clean = i;
 	u64_stats_update_begin(&tx_ring->tx_syncp);