[PATCH] [51/139] 8139cp: fix checksum broken

[Andi Kleen]

2.6.35-longterm review patch.  If anyone has any objections, please let me know.

------------------

From: Shan Wei <shanwei@xxxxxxxxxxxxxx>

[ Upstream commit 24b7ea9f6c9787fad885442ed0cc010f1aa69cca ]

I am not family with RealTek RTL-8139C+ series 10/100 PCI Ethernet driver.
I try to guess the meaning of RxProtoIP and IPFail.
RxProtoIP stands for received IPv4 packet that upper protocol is not tcp and udp.
!(status & IPFail) is true means that driver correctly to check checksum in IPv4 header.

If these are right, driver will set ip_summed with CHECKSUM_UNNECESSARY for other
upper protocol, e.g. sctp, igmp protocol. This will cause protocol stack ignores
checksum check for packets with invalid checksum.

This patch is only compile-test.

Signed-off-by: Shan Wei <shanwei@xxxxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>
Signed-off-by: Andi Kleen <ak@xxxxxxxxxxxxxxx>

---
 drivers/net/8139cp.c |   10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

Index: linux-2.6.35.y/drivers/net/8139cp.c
===================================================================
--- linux-2.6.35.y.orig/drivers/net/8139cp.c
+++ linux-2.6.35.y/drivers/net/8139cp.c
@@ -490,13 +490,11 @@ static inline unsigned int cp_rx_csum_ok
 {
 	unsigned int protocol = (status >> 16) & 0x3;
 
-	if (likely((protocol == RxProtoTCP) && (!(status & TCPFail))))
+	if (((protocol == RxProtoTCP) && !(status & TCPFail)) ||
+	    ((protocol == RxProtoUDP) && !(status & UDPFail)))
 		return 1;
-	else if ((protocol == RxProtoUDP) && (!(status & UDPFail)))
-		return 1;
-	else if ((protocol == RxProtoIP) && (!(status & IPFail)))
-		return 1;
-	return 0;
+	else
+		return 0;
 }
 
 static int cp_rx_poll(struct napi_struct *napi, int budget)
--
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