Re: [Linux-kernel] [PATCH 3/4] usbnet: smsc95xx: check for csum being in last four bytes

[Ben Hutchings]

On Tue, 2018-10-02 at 10:26 +0100, Ben Dooks wrote:
[...]
> @@ -2031,7 +2045,8 @@ static struct sk_buff *smsc95xx_tx_fixup(struct usbnet *dev,
> > Â	}
> Â
> Â	if (csum) {
> -		if (skb->len <= 45) {
> +		/* note, csum does not work if csum in last DWORD of packet */
> +		if (skb->len <= 45 || !smsc95xx_can_checksum(skb)) {

It would make more sense to move the length check into
smsc95xx_can_checksum() as well.

Ben.

> Â			/* workaround - hardware tx checksum does not work
> Â			Â* properly with extremely small packets */
> Â			long csstart = skb_checksum_start_offset(skb);
-- 
Ben Hutchings, Software Developer                Â        Codethink Ltd
https://www.codethink.co.uk/                 Dale House, 35 Dale Street
                                     Manchester, M1 2HF, United Kingdom