net/mlx4_en: Fix handling of dma_map failure

Result of skb_frag_dma_map() and dma_map_single() wasn't checked.
Added a check and proper handling in case of failure.
Moved the mapping to the beginning of mlx4_en_xmit(), before updating
the ring data structure to make error handling easier.
Signed-off-by: Amir Vadai <amirv@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/mellanox/mlx4/en_tx.c

@@ -588,6 +588,7 @@ netdev_tx_t mlx4_en_xmit(struct sk_buff *skb, struct net_device *dev)
 {
 	struct mlx4_en_priv *priv = netdev_priv(dev);
 	struct mlx4_en_dev *mdev = priv->mdev;
+	struct device *ddev = priv->ddev;
 	struct mlx4_en_tx_ring *ring;
 	struct mlx4_en_tx_desc *tx_desc;
 	struct mlx4_wqe_data_seg *data;
@@ -674,6 +675,56 @@ netdev_tx_t mlx4_en_xmit(struct sk_buff *skb, struct net_device *dev)
 	tx_info->skb = skb;
 	tx_info->nr_txbb = nr_txbb;
 
+	if (lso_header_size)
+		data = ((void *)&tx_desc->lso + ALIGN(lso_header_size + 4,
+						      DS_SIZE));
+	else
+		data = &tx_desc->data;
+
+	/* valid only for none inline segments */
+	tx_info->data_offset = (void *)data - (void *)tx_desc;
+
+	tx_info->linear = (lso_header_size < skb_headlen(skb) &&
+			   !is_inline(skb, NULL)) ? 1 : 0;
+
+	data += skb_shinfo(skb)->nr_frags + tx_info->linear - 1;
+
+	if (is_inline(skb, &fragptr)) {
+		tx_info->inl = 1;
+	} else {
+		/* Map fragments */
+		for (i = skb_shinfo(skb)->nr_frags - 1; i >= 0; i--) {
+			frag = &skb_shinfo(skb)->frags[i];
+			dma = skb_frag_dma_map(ddev, frag,
+					       0, skb_frag_size(frag),
+					       DMA_TO_DEVICE);
+			if (dma_mapping_error(ddev, dma))
+				goto tx_drop_unmap;
+
+			data->addr = cpu_to_be64(dma);
+			data->lkey = cpu_to_be32(mdev->mr.key);
+			wmb();
+			data->byte_count = cpu_to_be32(skb_frag_size(frag));
+			--data;
+		}
+
+		/* Map linear part */
+		if (tx_info->linear) {
+			u32 byte_count = skb_headlen(skb) - lso_header_size;
+			dma = dma_map_single(ddev, skb->data +
+					     lso_header_size, byte_count,
+					     PCI_DMA_TODEVICE);
+			if (dma_mapping_error(ddev, dma))
+				goto tx_drop_unmap;
+
+			data->addr = cpu_to_be64(dma);
+			data->lkey = cpu_to_be32(mdev->mr.key);
+			wmb();
+			data->byte_count = cpu_to_be32(byte_count);
+		}
+		tx_info->inl = 0;
+	}
+
 	/*
 	 * For timestamping add flag to skb_shinfo and
 	 * set flag for further reference
@@ -720,8 +771,6 @@ netdev_tx_t mlx4_en_xmit(struct sk_buff *skb, struct net_device *dev)
 		/* Copy headers;
 		 * note that we already verified that it is linear */
 		memcpy(tx_desc->lso.header, skb->data, lso_header_size);
-		data = ((void *) &tx_desc->lso +
-			ALIGN(lso_header_size + 4, DS_SIZE));
 
 		priv->port_stats.tso_packets++;
 		i = ((skb->len - lso_header_size) / skb_shinfo(skb)->gso_size) +
@@ -733,7 +782,6 @@ netdev_tx_t mlx4_en_xmit(struct sk_buff *skb, struct net_device *dev)
 		op_own = cpu_to_be32(MLX4_OPCODE_SEND) |
 			((ring->prod & ring->size) ?
 			 cpu_to_be32(MLX4_EN_BIT_DESC_OWN) : 0);
-		data = &tx_desc->data;
 		tx_info->nr_bytes = max_t(unsigned int, skb->len, ETH_ZLEN);
 		ring->packets++;
 
@@ -742,38 +790,7 @@ netdev_tx_t mlx4_en_xmit(struct sk_buff *skb, struct net_device *dev)
 	netdev_tx_sent_queue(ring->tx_queue, tx_info->nr_bytes);
 	AVG_PERF_COUNTER(priv->pstats.tx_pktsz_avg, skb->len);
 
-
-	/* valid only for none inline segments */
-	tx_info->data_offset = (void *) data - (void *) tx_desc;
-
-	tx_info->linear = (lso_header_size < skb_headlen(skb) && !is_inline(skb, NULL)) ? 1 : 0;
-	data += skb_shinfo(skb)->nr_frags + tx_info->linear - 1;
-
-	if (!is_inline(skb, &fragptr)) {
-		/* Map fragments */
-		for (i = skb_shinfo(skb)->nr_frags - 1; i >= 0; i--) {
-			frag = &skb_shinfo(skb)->frags[i];
-			dma = skb_frag_dma_map(priv->ddev, frag,
-					       0, skb_frag_size(frag),
-					       DMA_TO_DEVICE);
-			data->addr = cpu_to_be64(dma);
-			data->lkey = cpu_to_be32(mdev->mr.key);
-			wmb();
-			data->byte_count = cpu_to_be32(skb_frag_size(frag));
-			--data;
-		}
-
-		/* Map linear part */
-		if (tx_info->linear) {
-			dma = dma_map_single(priv->ddev, skb->data + lso_header_size,
-					     skb_headlen(skb) - lso_header_size, PCI_DMA_TODEVICE);
-			data->addr = cpu_to_be64(dma);
-			data->lkey = cpu_to_be32(mdev->mr.key);
-			wmb();
-			data->byte_count = cpu_to_be32(skb_headlen(skb) - lso_header_size);
-		}
-		tx_info->inl = 0;
-	} else {
+	if (tx_info->inl) {
 		build_inline_wqe(tx_desc, skb, real_size, &vlan_tag, tx_ind, fragptr);
 		tx_info->inl = 1;
 	}
@@ -813,6 +830,16 @@ netdev_tx_t mlx4_en_xmit(struct sk_buff *skb, struct net_device *dev)
 
 	return NETDEV_TX_OK;
 
+tx_drop_unmap:
+	en_err(priv, "DMA mapping error\n");
+
+	for (i++; i < skb_shinfo(skb)->nr_frags; i++) {
+		data++;
+		dma_unmap_page(ddev, (dma_addr_t) be64_to_cpu(data->addr),
+			       be32_to_cpu(data->byte_count),
+			       PCI_DMA_TODEVICE);
+	}
+
 tx_drop:
 	dev_kfree_skb_any(skb);
 	priv->stats.tx_dropped++;