net: systemport: Free DMA coherent descriptors on errors

In case bcm_sysport_init_tx_ring() is not able to allocate ring->cbs, we
would return with an error, and call bcm_sysport_fini_tx_ring() and it
would see that ring->cbs is NULL and do nothing. This would leak the
coherent DMA descriptor area, so we need to free it on error before
returning.
Reported-by: NEric Dumazet <edumazet@gmail.com>
Fixes: 80105bef ("net: systemport: add Broadcom SYSTEMPORT Ethernet MAC driver")
Signed-off-by: NFlorian Fainelli <f.fainelli@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/broadcom/bcmsysport.c

@@ -1346,6 +1346,8 @@ static int bcm_sysport_init_tx_ring(struct bcm_sysport_priv *priv,
 
 	ring->cbs = kcalloc(size, sizeof(struct bcm_sysport_cb), GFP_KERNEL);
 	if (!ring->cbs) {
+		dma_free_coherent(kdev, sizeof(struct dma_desc),
+				  ring->desc_cpu, ring->desc_dma);
 		netif_err(priv, hw, priv->netdev, "CB allocation failed\n");
 		return -ENOMEM;
 	}