From: Daniel Hellstrom <daniel@gaisler.com>
Date: Fri, 14 Jan 2011 03:02:40 +0000 (+0000)
Subject: GRETH: fixed skb buffer memory leak on frame errors
X-Git-Url: http://drtracing.org/?a=commitdiff_plain;h=b669e7f0580f3c0058f1b32c276ef6da8f05c138;p=deliverable%2Flinux.git

GRETH: fixed skb buffer memory leak on frame errors

A new SKB buffer should not be allocated when the old SKB is reused.

Signed-off-by: Daniel Hellstrom <daniel@gaisler.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---

diff --git a/drivers/net/greth.c b/drivers/net/greth.c
index 869e38d6f41b..9386bce9dea5 100644
--- a/drivers/net/greth.c
+++ b/drivers/net/greth.c
@@ -870,10 +870,9 @@ static int greth_rx_gbit(struct net_device *dev, int limit)
 			}
 		}
 
-		/* Allocate new skb to replace current */
-		newskb = netdev_alloc_skb(dev, MAX_FRAME_SIZE + NET_IP_ALIGN);
-
-		if (!bad && newskb) {
+		/* Allocate new skb to replace current, not needed if the
+		 * current skb can be reused */
+		if (!bad && (newskb=netdev_alloc_skb(dev, MAX_FRAME_SIZE + NET_IP_ALIGN))) {
 			skb_reserve(newskb, NET_IP_ALIGN);
 
 			dma_addr = dma_map_single(greth->dev,
@@ -910,11 +909,22 @@ static int greth_rx_gbit(struct net_device *dev, int limit)
 				if (net_ratelimit())
 					dev_warn(greth->dev, "Could not create DMA mapping, dropping packet\n");
 				dev_kfree_skb(newskb);
+				/* reusing current skb, so it is a drop */
 				dev->stats.rx_dropped++;
 			}
+		} else if (bad) {
+			/* Bad Frame transfer, the skb is reused */
+			dev->stats.rx_dropped++;
 		} else {
+			/* Failed Allocating a new skb. This is rather stupid
+			 * but the current "filled" skb is reused, as if
+			 * transfer failure. One could argue that RX descriptor
+			 * table handling should be divided into cleaning and
+			 * filling as the TX part of the driver
+			 */
 			if (net_ratelimit())
 				dev_warn(greth->dev, "Could not allocate SKB, dropping packet\n");
+			/* reusing current skb, so it is a drop */
 			dev->stats.rx_dropped++;
 		}