diff options
author | Oliver Hartkopp <oliver@hartkopp.net> | 2009-12-11 23:13:21 -0500 |
---|---|---|
committer | David S. Miller <davem@davemloft.net> | 2009-12-13 22:47:42 -0500 |
commit | c7cd606f60e7679c7f9eee7010f02a6f000209c1 (patch) | |
tree | 31c19fd7617ede807757b0ae5c29d218587dc43f /include/linux/can/dev.h | |
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/linux/can/dev.h')
-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 1ed2a5cc03f5..3db7767d2a17 100644 --- a/include/linux/can/dev.h +++ b/include/linux/can/dev.h | |||
@@ -51,6 +51,15 @@ struct can_priv { | |||
51 | struct sk_buff **echo_skb; | 51 | struct sk_buff **echo_skb; |
52 | }; | 52 | }; |
53 | 53 | ||
54 | /* | ||
55 | * get_can_dlc(value) - helper macro to cast a given data length code (dlc) | ||
56 | * to __u8 and ensure the dlc value to be max. 8 bytes. | ||
57 | * | ||
58 | * To be used in the CAN netdriver receive path to ensure conformance with | ||
59 | * ISO 11898-1 Chapter 8.4.2.3 (DLC field) | ||
60 | */ | ||
61 | #define get_can_dlc(i) (min_t(__u8, (i), 8)) | ||
62 | |||
54 | struct net_device *alloc_candev(int sizeof_priv, unsigned int echo_skb_max); | 63 | struct net_device *alloc_candev(int sizeof_priv, unsigned int echo_skb_max); |
55 | void free_candev(struct net_device *dev); | 64 | void free_candev(struct net_device *dev); |
56 | 65 | ||