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>

1 files changed, 11 insertions, 8 deletions

diff --git a/drivers/net/atlx/atl1.c b/drivers/net/atlx/atl1.c
index f12e3d12474b..e6a7bb79d4df 100644
--- 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;
 }