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| author |   Alex Elder <elder@linaro.org> | 2021-03-15 16:51:49 -0500 |
|---|---|---|
| committer |   David S. Miller <davem@davemloft.net> | 2021-03-15 20:41:58 -0700 |
| commit | 16653c16d282e768763b2e8cc78f75df8fd53992 (patch) | |
| tree | 9045ff0c70cb92e0cbbc2a2a6cb9de54d03787aa /include | |
| parent | net: qualcomm: rmnet: kill RMNET_MAP_GET_*() accessor macros (diff) | |
| download | linux-dev-16653c16d282e768763b2e8cc78f75df8fd53992.tar.xz linux-dev-16653c16d282e768763b2e8cc78f75df8fd53992.zip | |
net: qualcomm: rmnet: use masks instead of C bit-fields
The actual layout of bits defined in C bit-fields (e.g. int foo : 3)
is implementation-defined. Structures defined in <linux/if_rmnet.h>
address this by specifying all bit-fields twice, to cover two
possible layouts.
I think this pattern is repetitive and noisy, and I find the whole
notion of compiler "bitfield endianness" to be non-intuitive.
Stop using C bit-fields for the command/data flag and the pad length
fields in the rmnet_map structure, and define a single-byte flags
field instead. Define a mask for the single-bit "command" flag,
and another mask for the encoded pad length. The content of both
fields can be accessed using a simple bitwise AND operation.
Signed-off-by: Alex Elder <elder@linaro.org>
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Reviewed-by: Alexander Duyck <alexanderduyck@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/if_rmnet.h | 23 |
1 files changed, 10 insertions, 13 deletions
diff --git a/include/linux/if_rmnet.h b/include/linux/if_rmnet.h index 8c7845baf383..a02f0a3df1d9 100644 --- a/include/linux/if_rmnet.h +++ b/include/linux/if_rmnet.h @@ -6,21 +6,18 @@ #define _LINUX_IF_RMNET_H_ struct rmnet_map_header { -#if defined(__LITTLE_ENDIAN_BITFIELD) - u8 pad_len:6; - u8 reserved_bit:1; - u8 cd_bit:1; -#elif defined (__BIG_ENDIAN_BITFIELD) - u8 cd_bit:1; - u8 reserved_bit:1; - u8 pad_len:6; -#else -#error "Please fix <asm/byteorder.h>" -#endif - u8 mux_id; - __be16 pkt_len; + u8 flags; /* MAP_CMD_FLAG, MAP_PAD_LEN_MASK */ + u8 mux_id; + __be16 pkt_len; /* Length of packet, including pad */ } __aligned(1); +/* rmnet_map_header flags field: + * PAD_LEN: number of pad bytes following packet data + * CMD: 1 = packet contains a MAP command; 0 = packet contains data + */ +#define MAP_PAD_LEN_MASK GENMASK(5, 0) +#define MAP_CMD_FLAG BIT(7) + struct rmnet_map_dl_csum_trailer { u8 reserved1; #if defined(__LITTLE_ENDIAN_BITFIELD) |