diff options
| author | Oliver Hartkopp <oliver@hartkopp.net> | 2009-12-12 04:13:21 +0000 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2009-12-13 19:47:42 -0800 |
| commit | c7cd606f60e7679c7f9eee7010f02a6f000209c1 (patch) | |
| tree | 31c19fd7617ede807757b0ae5c29d218587dc43f /include | |
| parent | d90a909e1f3e006a1d57fe11fd417173b6494701 (diff) | |
can: Fix data length code handling in rx path
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: Oliver Hartkopp <oliver@hartkopp.net>
Signed-off-by: Wolfgang Grandegger <wg@grandegger.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/can/dev.h | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/include/linux/can/dev.h b/include/linux/can/dev.h index 1ed2a5cc03f..3db7767d2a1 100644 --- a/include/linux/can/dev.h +++ b/include/linux/can/dev.h @@ -51,6 +51,15 @@ struct can_priv { struct sk_buff **echo_skb; }; +/* + * get_can_dlc(value) - helper macro to cast a given data length code (dlc) + * to __u8 and ensure the dlc value to be max. 8 bytes. + * + * To be used in the CAN netdriver receive path to ensure conformance with + * ISO 11898-1 Chapter 8.4.2.3 (DLC field) + */ +#define get_can_dlc(i) (min_t(__u8, (i), 8)) + struct net_device *alloc_candev(int sizeof_priv, unsigned int echo_skb_max); void free_candev(struct net_device *dev); |