atl1: deal with hardware rx checksum bug

The L1 hardware contains a bug that flags a fragmented IP packet
as having an incorrect TCP/UDP checksum, even though the packet
is perfectly valid and its checksum is correct.  There's no way to
distinguish between one of these good packets and a packet that
actually contains a TCP/UDP checksum error, so all we can do is
allow the packet to be handed up to the higher layers and let it
be sorted out there.

Add a comment describing this condition and remove the code that
currently fails to handle what may or may not be a checksum error.

Signed-off-by: Jay Cliburn <jacliburn@bellsouth.net>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

diff --git a/drivers/net/atlx/atl1.c b/drivers/net/atlx/atl1.c
index f12e3d12474b0701a5a72baaf0d4213d5f36203d..e6a7bb79d4dfdf17f9eb272359b038613f8fec18 100644 (file)
--- a/drivers/net/atlx/atl1.c
+++ b/drivers/net/atlx/atl1.c
@@ -1790,6 +1790,17 @@ static void atl1_rx_checksum(struct atl1_adapter *adapter,
 {
        struct pci_dev *pdev = adapter->pdev;
 
+       /*
+        * The L1 hardware contains a bug that erroneously sets the
+        * PACKET_FLAG_ERR and ERR_FLAG_L4_CHKSUM bits whenever a
+        * fragmented IP packet is received, even though the packet
+        * is perfectly valid and its checksum is correct. There's
+        * no way to distinguish between one of these good packets
+        * and a packet that actually contains a TCP/UDP checksum
+        * error, so all we can do is allow it to be handed up to
+        * the higher layers and let it be sorted out there.
+        */
+
        skb->ip_summed = CHECKSUM_NONE;
 
        if (unlikely(rrd->pkt_flg & PACKET_FLAG_ERR)) {
@@ -1816,14 +1827,6 @@ static void atl1_rx_checksum(struct atl1_adapter *adapter,
                return;
        }
 
-       /* IPv4, but hardware thinks its checksum is wrong */
-       if (netif_msg_rx_err(adapter))
-               dev_printk(KERN_DEBUG, &pdev->dev,
-                       "hw csum wrong, pkt_flag:%x, err_flag:%x\n",
-                       rrd->pkt_flg, rrd->err_flg);
-       skb->ip_summed = CHECKSUM_COMPLETE;
-       skb->csum = htons(rrd->xsz.xsum_sz.rx_chksum);
-       adapter->hw_csum_err++;
        return;
 }