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atl1: deal with hardware rx checksum bug

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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>
This commit is contained in:
Jay Cliburn 2008-08-04 19:05:10 -05:00 committed by Jeff Garzik
parent f0f422e573
commit c2ac3ef35c
1 changed files with 11 additions and 8 deletions
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19
drivers/net/atlx/atl1.c
View file

@ -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;
}