Merge branch 'oom_fixes'

Florian Fainelli says:

====================
net: systemport and bcmgenet OOM fixes

These two patches fix similar Out of Memory code paths in the SYSTEMPORT and
GENET drivers. Under high memory pressure, we could produce an OOPS by
passing a NULL pointer to dma_unmap_single().
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/broadcom/bcmsysport.c

@@ -534,6 +534,25 @@ static unsigned int bcm_sysport_desc_rx(struct bcm_sysport_priv *priv,
 	while ((processed < to_process) && (processed < budget)) {
 		cb = &priv->rx_cbs[priv->rx_read_ptr];
 		skb = cb->skb;
+
+		processed++;
+		priv->rx_read_ptr++;
+
+		if (priv->rx_read_ptr == priv->num_rx_bds)
+			priv->rx_read_ptr = 0;
+
+		/* We do not have a backing SKB, so we do not a corresponding
+		 * DMA mapping for this incoming packet since
+		 * bcm_sysport_rx_refill always either has both skb and mapping
+		 * or none.
+		 */
+		if (unlikely(!skb)) {
+			netif_err(priv, rx_err, ndev, "out of memory!\n");
+			ndev->stats.rx_dropped++;
+			ndev->stats.rx_errors++;
+			goto refill;
+		}
+
 		dma_unmap_single(kdev, dma_unmap_addr(cb, dma_addr),
 				 RX_BUF_LENGTH, DMA_FROM_DEVICE);
 
@@ -543,23 +562,11 @@ static unsigned int bcm_sysport_desc_rx(struct bcm_sysport_priv *priv,
 		status = (rsb->rx_status_len >> DESC_STATUS_SHIFT) &
 			  DESC_STATUS_MASK;
 
-		processed++;
-		priv->rx_read_ptr++;
-		if (priv->rx_read_ptr == priv->num_rx_bds)
-			priv->rx_read_ptr = 0;
-
 		netif_dbg(priv, rx_status, ndev,
 			  "p=%d, c=%d, rd_ptr=%d, len=%d, flag=0x%04x\n",
 			  p_index, priv->rx_c_index, priv->rx_read_ptr,
 			  len, status);
 
-		if (unlikely(!skb)) {
-			netif_err(priv, rx_err, ndev, "out of memory!\n");
-			ndev->stats.rx_dropped++;
-			ndev->stats.rx_errors++;
-			goto refill;
-		}
-
 		if (unlikely(!(status & DESC_EOP) || !(status & DESC_SOP))) {
 			netif_err(priv, rx_status, ndev, "fragmented packet!\n");
 			ndev->stats.rx_dropped++;

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

@@ -1274,12 +1274,29 @@ static unsigned int bcmgenet_desc_rx(struct bcmgenet_priv *priv,
 
 	while ((rxpktprocessed < rxpkttoprocess) &&
 	       (rxpktprocessed < budget)) {
+		cb = &priv->rx_cbs[priv->rx_read_ptr];
+		skb = cb->skb;
+
+		rxpktprocessed++;
+
+		priv->rx_read_ptr++;
+		priv->rx_read_ptr &= (priv->num_rx_bds - 1);
+
+		/* We do not have a backing SKB, so we do not have a
+		 * corresponding DMA mapping for this incoming packet since
+		 * bcmgenet_rx_refill always either has both skb and mapping or
+		 * none.
+		 */
+		if (unlikely(!skb)) {
+			dev->stats.rx_dropped++;
+			dev->stats.rx_errors++;
+			goto refill;
+		}
+
 		/* Unmap the packet contents such that we can use the
 		 * RSV from the 64 bytes descriptor when enabled and save
 		 * a 32-bits register read
 		 */
-		cb = &priv->rx_cbs[priv->rx_read_ptr];
-		skb = cb->skb;
 		dma_unmap_single(&dev->dev, dma_unmap_addr(cb, dma_addr),
 				 priv->rx_buf_len, DMA_FROM_DEVICE);
 
@@ -1307,18 +1324,6 @@ static unsigned int bcmgenet_desc_rx(struct bcmgenet_priv *priv,
 			  __func__, p_index, priv->rx_c_index,
 			  priv->rx_read_ptr, dma_length_status);
 
-		rxpktprocessed++;
-
-		priv->rx_read_ptr++;
-		priv->rx_read_ptr &= (priv->num_rx_bds - 1);
-
-		/* out of memory, just drop packets at the hardware level */
-		if (unlikely(!skb)) {
-			dev->stats.rx_dropped++;
-			dev->stats.rx_errors++;
-			goto refill;
-		}
-
 		if (unlikely(!(dma_flag & DMA_EOP) || !(dma_flag & DMA_SOP))) {
 			netif_err(priv, rx_status, dev,
 				  "dropping fragmented packet!\n");