On 11/14/2018 02:50 PM, Ben Dooks wrote: > The manual states that the checksum cannot lie in the last DWORD of the > transmission, so add a basic check for this and fall back to software > checksumming the packet. > > This only seems to trigger for ACK packets with no options or data to > return to the other end, and the use of the tx-alignment option makes > it more likely to happen. > > Signed-off-by: Ben Dooks <ben.dooks@xxxxxxxxxxxxxxx> > --- > Fixes for v2: > - Fix spelling of check at Sergei's suggestion > - Move skb->len check into smsc95xx_can_tx_checksum() > - Change name of smsc95xx_can_checksum to explicitly say it is tx-csum > --- > drivers/net/usb/smsc95xx.c | 19 ++++++++++++++++++- > 1 file changed, 18 insertions(+), 1 deletion(-) > > diff --git a/drivers/net/usb/smsc95xx.c b/drivers/net/usb/smsc95xx.c > index 8f7c473f3260..cc78ef78cc93 100644 > --- a/drivers/net/usb/smsc95xx.c > +++ b/drivers/net/usb/smsc95xx.c > @@ -1997,6 +1997,23 @@ static u32 smsc95xx_calc_csum_preamble(struct sk_buff *skb) > return (high_16 << 16) | low_16; > } > > +/* The TX CSUM won't work if the checksum lies in the last 4 bytes of the > + * transmission. This is fairly unlikely, only seems to trigger with some > + * short TCP ACK packets sent. > + * > + * Note, this calculation should probably check for the alignment of the > + * data as well, but a straight check for csum being in the last four bytes > + * of the packet should be ok for now. > +*/ Missed a space before */. [...] MBR, Sergei
