dpaa2-eth: add software counter for Tx frames converted to S/G

With the previous commit, in case of insufficient SKB headroom on the Tx
path instead of reallocing the SKB we now send a S/G frame descriptor.
Export the number of occurences of this case as a per CPU counter (in
debugfs) and a total number in the ethtool statistics - "tx converted sg
frames'.
Signed-off-by: Ioana Ciornei <ioana.ciornei@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/freescale/dpaa2/dpaa2-eth-debugfs.c

@@ -19,14 +19,14 @@ static int dpaa2_dbg_cpu_show(struct seq_file *file, void *offset)
 	int i;
 
 	seq_printf(file, "Per-CPU stats for %s\n", priv->net_dev->name);
-	seq_printf(file, "%s%16s%16s%16s%16s%16s%16s%16s%16s\n",
+	seq_printf(file, "%s%16s%16s%16s%16s%16s%16s%16s%16s%16s\n",
 		   "CPU", "Rx", "Rx Err", "Rx SG", "Tx", "Tx Err", "Tx conf",
-		   "Tx SG", "Enq busy");
+		   "Tx SG", "Tx converted to SG", "Enq busy");
 
 	for_each_online_cpu(i) {
 		stats = per_cpu_ptr(priv->percpu_stats, i);
 		extras = per_cpu_ptr(priv->percpu_extras, i);
-		seq_printf(file, "%3d%16llu%16llu%16llu%16llu%16llu%16llu%16llu%16llu\n",
+		seq_printf(file, "%3d%16llu%16llu%16llu%16llu%16llu%16llu%16llu%16llu%16llu\n",
 			   i,
 			   stats->rx_packets,
 			   stats->rx_errors,
@@ -35,6 +35,7 @@ static int dpaa2_dbg_cpu_show(struct seq_file *file, void *offset)
 			   stats->tx_errors,
 			   extras->tx_conf_frames,
 			   extras->tx_sg_frames,
+			   extras->tx_converted_sg_frames,
 			   extras->tx_portal_busy);
 	}
 

drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c

@@ -960,6 +960,8 @@ static netdev_tx_t dpaa2_eth_tx(struct sk_buff *skb, struct net_device *net_dev)
 		err = build_sg_fd_single_buf(priv, skb, &fd);
 		percpu_extras->tx_sg_frames++;
 		percpu_extras->tx_sg_bytes += skb->len;
+		percpu_extras->tx_converted_sg_frames++;
+		percpu_extras->tx_converted_sg_bytes += skb->len;
 	} else {
 		err = build_single_fd(priv, skb, &fd);
 	}

drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.h

@@ -285,6 +285,9 @@ struct dpaa2_eth_drv_stats {
 	__u64	tx_sg_bytes;
 	__u64	rx_sg_frames;
 	__u64	rx_sg_bytes;
+	/* Linear skbs sent as a S/G FD due to insufficient headroom */
+	__u64	tx_converted_sg_frames;
+	__u64	tx_converted_sg_bytes;
 	/* Enqueues retried due to portal busy */
 	__u64	tx_portal_busy;
 };

drivers/net/ethernet/freescale/dpaa2/dpaa2-ethtool.c

@@ -45,6 +45,8 @@ static char dpaa2_ethtool_extras[][ETH_GSTRING_LEN] = {
 	"[drv] tx sg bytes",
 	"[drv] rx sg frames",
 	"[drv] rx sg bytes",
+	"[drv] tx converted sg frames",
+	"[drv] tx converted sg bytes",
 	"[drv] enqueue portal busy",
 	/* Channel stats */
 	"[drv] dequeue portal busy",