From: Sergei Shtylyov
> On 10/07/2014 05:19 PM, Lothar Wamann 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 Wamann <l...@karo-electronics.de>
> > ---
> > drivers/net/ethernet/freescale/fec_main.c | 25 +++++++++++++++++++++----
> > 1 file changed, 21 insertions(+), 4 deletions(-)
>
> > diff --git a/drivers/net/ethernet/freescale/fec_main.c
> > b/drivers/net/ethernet/freescale/fec_main.c
> > index 87975b5..eaaebad 100644
> > --- a/drivers/net/ethernet/freescale/fec_main.c
> > +++ b/drivers/net/ethernet/freescale/fec_main.c
> [...]
> > @@ -1348,7 +1360,7 @@ fec_enet_new_rxbdp(struct net_device *ndev, struct
> > bufdesc *bdp, struct
> sk_buff
> > }
> >
> > static bool fec_enet_copybreak(struct net_device *ndev, struct sk_buff
> > **skb,
> > - struct bufdesc *bdp, u32 length)
> > + struct bufdesc *bdp, u32 length, int swap)
>
> 'bool swap' perhaps?
>
> > @@ -1393,6 +1408,7 @@ fec_enet_rx_queue(struct net_device *ndev, int
> > budget, u16 queue_id)
> > u16 vlan_tag;
> > int index = 0;
> > bool is_copybreak;
> > + bool need_swap = id_entry->driver_data & FEC_QUIRK_SWAP_FRAME;
>
> ... especially talking this into account...
Hmmm... in that case you may not want the compiler to convert the bit value
to a 'bool' at all.
Passing 'id_entry->driver_data' through (that doesn't look like a field name for
'quirk flags) would generate better code.
Even better would be to reference the flag directly from 'ndev'.
A pointer indirection for the test if probably faster then passing another
argument.
David
