i40e/i40evf: Add a stat to keep track of linearization count

Keep track of how many times we ask the stack to linearize the
skb because the HW cannot handle skbs with more than 8 frags per
segment/single packet.

Change-ID: If455452060963a769bbe6112cba952e79e944b52
Signed-off-by: NAnjali Singhai Jain <anjali.singhai@intel.com>
Tested-by: NAndrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: NJeff Kirsher <jeffrey.t.kirsher@intel.com>

drivers/net/ethernet/intel/i40e/i40e.h

@@ -475,6 +475,7 @@ struct i40e_vsi {
 #endif
 	u32 tx_restart;
 	u32 tx_busy;
+	u64 tx_linearize;
 	u32 rx_buf_failed;
 	u32 rx_page_failed;
 

drivers/net/ethernet/intel/i40e/i40e_ethtool.c

@@ -87,6 +87,7 @@ static const struct i40e_stats i40e_gstrings_misc_stats[] = {
 	I40E_VSI_STAT("rx_broadcast", eth_stats.rx_broadcast),
 	I40E_VSI_STAT("tx_broadcast", eth_stats.tx_broadcast),
 	I40E_VSI_STAT("rx_unknown_protocol", eth_stats.rx_unknown_protocol),
+	I40E_VSI_STAT("tx_linearize", tx_linearize),
 };
 
 static int i40e_add_fdir_ethtool(struct i40e_vsi *vsi,

drivers/net/ethernet/intel/i40e/i40e_main.c

@@ -879,6 +879,7 @@ static void i40e_update_vsi_stats(struct i40e_vsi *vsi)
 	u32 rx_page, rx_buf;
 	u64 bytes, packets;
 	unsigned int start;
+	u64 tx_linearize;
 	u64 rx_p, rx_b;
 	u64 tx_p, tx_b;
 	u16 q;
@@ -897,7 +898,7 @@ static void i40e_update_vsi_stats(struct i40e_vsi *vsi)
 	 */
 	rx_b = rx_p = 0;
 	tx_b = tx_p = 0;
-	tx_restart = tx_busy = 0;
+	tx_restart = tx_busy = tx_linearize = 0;
 	rx_page = 0;
 	rx_buf = 0;
 	rcu_read_lock();
@@ -914,6 +915,7 @@ static void i40e_update_vsi_stats(struct i40e_vsi *vsi)
 		tx_p += packets;
 		tx_restart += p->tx_stats.restart_queue;
 		tx_busy += p->tx_stats.tx_busy;
+		tx_linearize += p->tx_stats.tx_linearize;
 
 		/* Rx queue is part of the same block as Tx queue */
 		p = &p[1];
@@ -930,6 +932,7 @@ static void i40e_update_vsi_stats(struct i40e_vsi *vsi)
 	rcu_read_unlock();
 	vsi->tx_restart = tx_restart;
 	vsi->tx_busy = tx_busy;
+	vsi->tx_linearize = tx_linearize;
 	vsi->rx_page_failed = rx_page;
 	vsi->rx_buf_failed = rx_buf;
 

drivers/net/ethernet/intel/i40e/i40e_txrx.c

@@ -2771,10 +2771,11 @@ static netdev_tx_t i40e_xmit_frame_ring(struct sk_buff *skb,
 	if (tsyn)
 		tx_flags |= I40E_TX_FLAGS_TSYN;
 
-	if (i40e_chk_linearize(skb, tx_flags))
+	if (i40e_chk_linearize(skb, tx_flags)) {
 		if (skb_linearize(skb))
 			goto out_drop;
-
+		tx_ring->tx_stats.tx_linearize++;
+	}
 	skb_tx_timestamp(skb);
 
 	/* always enable CRC insertion offload */

drivers/net/ethernet/intel/i40e/i40e_txrx.h

@@ -188,6 +188,7 @@ struct i40e_tx_queue_stats {
 	u64 restart_queue;
 	u64 tx_busy;
 	u64 tx_done_old;
+	u64 tx_linearize;
 };
 
 struct i40e_rx_queue_stats {

drivers/net/ethernet/intel/i40evf/i40e_txrx.c

@@ -1927,10 +1927,11 @@ static netdev_tx_t i40e_xmit_frame_ring(struct sk_buff *skb,
 	else if (tso)
 		tx_flags |= I40E_TX_FLAGS_TSO;
 
-	if (i40e_chk_linearize(skb, tx_flags))
+	if (i40e_chk_linearize(skb, tx_flags)) {
 		if (skb_linearize(skb))
 			goto out_drop;
-
+		tx_ring->tx_stats.tx_linearize++;
+	}
 	skb_tx_timestamp(skb);
 
 	/* always enable CRC insertion offload */

drivers/net/ethernet/intel/i40evf/i40e_txrx.h

@@ -187,6 +187,7 @@ struct i40e_tx_queue_stats {
 	u64 restart_queue;
 	u64 tx_busy;
 	u64 tx_done_old;
+	u64 tx_linearize;
 };
 
 struct i40e_rx_queue_stats {