atm: eni: Add check for dma_map_single

As the potential failure of the dma_map_single(),
it should be better to check it and return error
if fails.

Fixes: 1da177e ("Linux-2.6.12-rc2")
Signed-off-by: Jiasheng Jiang <jiasheng@iscas.ac.cn>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/atm/eni.c

@@ -1112,6 +1112,8 @@ DPRINTK("iovcnt = %d\n",skb_shinfo(skb)->nr_frags);
 	skb_data3 = skb->data[3];
 	paddr = dma_map_single(&eni_dev->pci_dev->dev,skb->data,skb->len,
 			       DMA_TO_DEVICE);
+	if (dma_mapping_error(&eni_dev->pci_dev->dev, paddr))
+		return enq_next;
 	ENI_PRV_PADDR(skb) = paddr;
 	/* prepare DMA queue entries */
 	j = 0;