This patch adds error checking of ctrlmode values for CAN devices. As
an example all availabe bits are implemented in the mcp251x driver.
Signed-off-by: NChristian Pellegrin <chripell@fsfe.org>
Acked-by: NWolfgang Grandegger <wg@grandegger.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

To prevent the CAN drivers to operate on invalid socketbuffers the skbs are
now checked and silently dropped at the xmit-function consistently.

Also the netdev stats are consistently using the CAN data length code (dlc)
for [rx|tx]_bytes now.
Signed-off-by: NOliver Hartkopp <oliver@hartkopp.net>
Acked-by: NWolfgang Grandegger <wg@grandegger.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

A valid CAN dataframe can have a data length code (DLC) of 0 .. 8 data bytes.

When reading the CAN controllers register the 4-bit value may contain values
from 0 .. 15 which may exceed the reserved space in the socket buffer!

The ISO 11898-1 Chapter 8.4.2.3 (DLC field) says that register values > 8
should be reduced to 8 without any error reporting or frame drop.

This patch introduces a new helper macro to cast a given 4-bit data length
code (dlc) to __u8 and ensure the DLC value to be max. 8 bytes.

The different handlings in the rx path of the CAN netdevice drivers are fixed.
Signed-off-by: NOliver Hartkopp <oliver@hartkopp.net>
Signed-off-by: NWolfgang Grandegger <wg@grandegger.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Signed-off-by: NBarry Song <21cnbao@gmail.com>
Signed-off-by: NH.J. Oertel <oe@port.de>
Signed-off-by: NWolfgang Grandegger <wg@grandegger.de>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>