[PATCHv4 1/1] net: fec: fix regression on i.MX28 introduced by rx_copybreak support

[Fabio Estevam]

On Fri, Nov 7, 2014 at 7:02 AM, Lothar Waßmann <LW at karo-electronics.de> wrote:
> commit 1b7bde6d659d ("net: fec: implement rx_copybreak to improve rx performance")
> introduced a regression for i.MX28. The swap_buffer() function doing
> the endian conversion of the received data on i.MX28 may access memory
> beyond the actual packet size in the DMA buffer. fec_enet_copybreak()
> does not copy those bytes, so that the last bytes of a packet may be
> filled with invalid data after swapping.
> This will likely lead to checksum errors on received packets.
> E.g. when trying to mount an NFS rootfs:
> UDP: bad checksum. From 192.168.1.225:111 to 192.168.100.73:44662 ulen 36
>
> Do the byte swapping and copying to the new skb in one go if
> necessary.
>
> Signed-off-by: Lothar Waßmann <LW at KARO-electronics.de>

With this patch I am able to NFS mount on mx28 again. Thanks, Lothar!

Tested-by: Fabio Estevam <fabio.estevam at freescale.com>