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can.h: make padding given by gcc explicit 

The current definition of struct can_frame has a 16-byte size, with 8-byte
alignment, but the 3 bytes of padding are not explicit like the similar 2 bytes
of padding of struct canfd_frame. Make it explicit so it is easier to read.

Signed-off-by: Shawn Landden <shawn@churchofgit.com>
Acked-by: Oliver Hartkopp <socketcan@hartkopp.net>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
This commit is contained in:
Shawn Landden 2015-05-05 09:07:16 -07:00 committed by Marc Kleine-Budde
parent 239fb791d4
commit a2f1183599
2 changed files with 9 additions and 0 deletions
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3
Documentation/networking/can.txt
View File

@ -268,6 +268,9 @@ solution for a couple of reasons:
struct can_frame {
canid_t can_id; /* 32 bit CAN_ID + EFF/RTR/ERR flags */
__u8 can_dlc; /* frame payload length in byte (0 .. 8) */
__u8 __pad; /* padding */
__u8 __res0; /* reserved / padding */
__u8 __res1; /* reserved / padding */
__u8 data[8] __attribute__((aligned(8)));
};

6
include/uapi/linux/can.h
View File

@ -95,11 +95,17 @@ typedef __u32 can_err_mask_t;
* @can_dlc: frame payload length in byte (0 .. 8) aka data length code
* N.B. the DLC field from ISO 11898-1 Chapter 8.4.2.3 has a 1:1
* mapping of the 'data length code' to the real payload length
* @__pad: padding
* @__res0: reserved / padding
* @__res1: reserved / padding
* @data: CAN frame payload (up to 8 byte)
*/
struct can_frame {
canid_t can_id; /* 32 bit CAN_ID + EFF/RTR/ERR flags */
__u8 can_dlc; /* frame payload length in byte (0 .. CAN_MAX_DLEN) */
__u8 __pad; /* padding */
__u8 __res0; /* reserved / padding */
__u8 __res1; /* reserved / padding */
__u8 data[CAN_MAX_DLEN] __attribute__((aligned(8)));
};