8139cp: fix coherent mapping leak in error path.

cp_open
[...]
        rc = cp_alloc_rings(cp);
        if (rc)
                return rc;

cp_alloc_rings
[...]
        mem = dma_alloc_coherent(&cp->pdev->dev, CP_RING_BYTES,
                                 &cp->ring_dma, GFP_KERNEL);

- cp_alloc_rings never frees the coherent mapping it allocates
- neither do cp_open when cp_alloc_rings fails

Signed-off-by: Francois Romieu <romieu@fr.zoreil.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/realtek/8139cp.c

@@ -1060,17 +1060,22 @@ static int cp_init_rings (struct cp_private *cp)
 
 static int cp_alloc_rings (struct cp_private *cp)
 {
+	struct device *d = &cp->pdev->dev;
 	void *mem;
+	int rc;
 
-	mem = dma_alloc_coherent(&cp->pdev->dev, CP_RING_BYTES,
-				 &cp->ring_dma, GFP_KERNEL);
+	mem = dma_alloc_coherent(d, CP_RING_BYTES, &cp->ring_dma, GFP_KERNEL);
 	if (!mem)
 		return -ENOMEM;
 
 	cp->rx_ring = mem;
 	cp->tx_ring = &cp->rx_ring[CP_RX_RING_SIZE];
 
-	return cp_init_rings(cp);
+	rc = cp_init_rings(cp);
+	if (rc < 0)
+		dma_free_coherent(d, CP_RING_BYTES, cp->rx_ring, cp->ring_dma);
+
+	return rc;
 }
 
 static void cp_clean_rings (struct cp_private *cp)