diff options
| author | Steve Glendinning <steve.glendinning@smsc.com> | 2010-03-18 22:18:41 -0700 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2010-03-18 22:18:41 -0700 |
| commit | 11bc3088373e913f165a8652601c6f8b8dc4aea2 (patch) | |
| tree | 5a82487caf4de60681ac0bd743bfeba4851254b8 | |
| parent | 0ecad5a262923967147e2d1725e277a2a5fbcdd4 (diff) | |
| download | lwn-11bc3088373e913f165a8652601c6f8b8dc4aea2.tar.gz lwn-11bc3088373e913f165a8652601c6f8b8dc4aea2.zip | |
smsc95xx: Fix tx checksum offload for small packets
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>
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | drivers/net/usb/smsc95xx.c | 18 |
1 files changed, 15 insertions, 3 deletions
diff --git a/drivers/net/usb/smsc95xx.c b/drivers/net/usb/smsc95xx.c index d222d7e25273..73f9a31cf94d 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); |