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Commit c2ac3ef3 authored by Jay Cliburn's avatar Jay Cliburn Committed by Jeff Garzik
Browse files

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: default avatarJay Cliburn <jacliburn@bellsouth.net>
Signed-off-by: default avatarJeff Garzik <jgarzik@redhat.com>
parent f0f422e5

drivers/net/atlx/atl1.c

+11 −8
Original line number Diff line number Diff line
@@ -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;

}