| Message ID | 1268940010-19394-1-git-send-email-steve.glendinning@smsc.com |
|---|---|
| State | Accepted, archived |
| Delegated to: | David Miller |
| Headers | show |
From: Steve Glendinning <steve.glendinning@smsc.com> Date: Thu, 18 Mar 2010 19:20:10 +0000 > TX checksum offload does not work properly when transmitting > UDP packets with 0, 1 or 2 bytes of data. This patch works > around the problem by calculating checksums for these packets > in the driver. > > Signed-off-by: Steve Glendinning <steve.glendinning@smsc.com> Applied, but I had to fix up trailing whitespace on one of the patch's lines. Please check for and fix up such trivial matters before I ever have to see the patch in the future, thanks. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/net/usb/smsc95xx.c b/drivers/net/usb/smsc95xx.c index d222d7e..829963f 100644 --- a/drivers/net/usb/smsc95xx.c +++ b/drivers/net/usb/smsc95xx.c @@ -1189,9 +1189,21 @@ static struct sk_buff *smsc95xx_tx_fixup(struct usbnet *dev, } if (csum) { - u32 csum_preamble = smsc95xx_calc_csum_preamble(skb); - skb_push(skb, 4); - memcpy(skb->data, &csum_preamble, 4); + if (skb->len <= 45) { + /* workaround - hardware tx checksum does not work + * properly with extremely small packets */ + long csstart = skb->csum_start - skb_headroom(skb); + __wsum calc = csum_partial(skb->data + csstart, + skb->len - csstart, 0); + *((__sum16 *)(skb->data + csstart + + skb->csum_offset)) = csum_fold(calc); + + csum = false; + } else { + u32 csum_preamble = smsc95xx_calc_csum_preamble(skb); + skb_push(skb, 4); + memcpy(skb->data, &csum_preamble, 4); + } } skb_push(skb, 4);
TX checksum offload does not work properly when transmitting UDP packets with 0, 1 or 2 bytes of data. This patch works around the problem by calculating checksums for these packets in the driver. Signed-off-by: Steve Glendinning <steve.glendinning@smsc.com> --- drivers/net/usb/smsc95xx.c | 18 +++++++++++++++--- 1 files changed, 15 insertions(+), 3 deletions(-)