net: bcmgenet: log RX buffer allocation and RX/TX dma failures

To help troubleshoot heavy memory pressure conditions, add a bunch of
statistics counter to log RX buffer allocation and RX/TX DMA mapping
failures. These are reported like any other counters through the ethtool
stats interface.

Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/broadcom/genet/bcmgenet.c

@@ -613,6 +613,9 @@ static const struct bcmgenet_stats bcmgenet_gstrings_stats[] = {
 			UMAC_RBUF_OVFL_CNT),
 	STAT_GENET_MISC("rbuf_err_cnt", mib.rbuf_err_cnt, UMAC_RBUF_ERR_CNT),
 	STAT_GENET_MISC("mdf_err_cnt", mib.mdf_err_cnt, UMAC_MDF_ERR_CNT),
+	STAT_GENET_MIB_RX("alloc_rx_buff_failed", mib.alloc_rx_buff_failed),
+	STAT_GENET_MIB_RX("rx_dma_failed", mib.rx_dma_failed),
+	STAT_GENET_MIB_TX("tx_dma_failed", mib.tx_dma_failed),
 };
 
 #define BCMGENET_STATS_LEN	ARRAY_SIZE(bcmgenet_gstrings_stats)
@@ -989,6 +992,7 @@ static int bcmgenet_xmit_single(struct net_device *dev,
 	mapping = dma_map_single(kdev, skb->data, skb_len, DMA_TO_DEVICE);
 	ret = dma_mapping_error(kdev, mapping);
 	if (ret) {
+		priv->mib.tx_dma_failed++;
 		netif_err(priv, tx_err, dev, "Tx DMA map failed\n");
 		dev_kfree_skb(skb);
 		return ret;
@@ -1035,6 +1039,7 @@ static int bcmgenet_xmit_frag(struct net_device *dev,
 				   skb_frag_size(frag), DMA_TO_DEVICE);
 	ret = dma_mapping_error(kdev, mapping);
 	if (ret) {
+		priv->mib.tx_dma_failed++;
 		netif_err(priv, tx_err, dev, "%s: Tx DMA map failed\n",
 			  __func__);
 		return ret;
@@ -1231,6 +1236,7 @@ static int bcmgenet_rx_refill(struct bcmgenet_priv *priv, struct enet_cb *cb)
 				 priv->rx_buf_len, DMA_FROM_DEVICE);
 	ret = dma_mapping_error(kdev, mapping);
 	if (ret) {
+		priv->mib.rx_dma_failed++;
 		bcmgenet_free_cb(cb);
 		netif_err(priv, rx_err, priv->dev,
 			  "%s DMA map failed\n", __func__);
@@ -1397,8 +1403,10 @@ static unsigned int bcmgenet_desc_rx(struct bcmgenet_priv *priv,
 		/* refill RX path on the current control block */
 refill:
 		err = bcmgenet_rx_refill(priv, cb);
-		if (err)
+		if (err) {
+			priv->mib.alloc_rx_buff_failed++;
 			netif_err(priv, rx_err, dev, "Rx refill failed\n");
+		}
 
 		rxpktprocessed++;
 		priv->rx_read_ptr++;

drivers/net/ethernet/broadcom/genet/bcmgenet.h

@@ -143,6 +143,9 @@ struct bcmgenet_mib_counters {
 	u32	rbuf_ovflow_cnt;
 	u32	rbuf_err_cnt;
 	u32	mdf_err_cnt;
+	u32	alloc_rx_buff_failed;
+	u32	rx_dma_failed;
+	u32	tx_dma_failed;
 };
 
 #define UMAC_HD_BKP_CTRL		0x004