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. Instead, define a single-byte
flags field, and use the functions defined in <linux/bitfield.h>,
along with field mask constants to extract or assign values within
that field.
Signed-off-by: Alex Elder <el...@linaro.org>
---
.../ethernet/qualcomm/rmnet/rmnet_handlers.c | 5 ++--
.../ethernet/qualcomm/rmnet/rmnet_map_data.c | 4 +++-
include/linux/if_rmnet.h | 23 ++++++++-----------
3 files changed, 16 insertions(+), 16 deletions(-)
diff --git a/drivers/net/ethernet/qualcomm/rmnet/rmnet_handlers.c
b/drivers/net/ethernet/qualcomm/rmnet/rmnet_handlers.c
index 2a6b2a609884c..30f8e2f02696b 100644
--- a/drivers/net/ethernet/qualcomm/rmnet/rmnet_handlers.c
+++ b/drivers/net/ethernet/qualcomm/rmnet/rmnet_handlers.c
@@ -4,6 +4,7 @@
* RMNET Data ingress/egress handler
*/
+#include <linux/bitfield.h>
#include <linux/netdevice.h>
#include <linux/netdev_features.h>
#include <linux/if_arp.h>
@@ -61,7 +62,7 @@ __rmnet_map_ingress_handler(struct sk_buff *skb,
u16 len, pad;
u8 mux_id;
- if (map_header->cd_bit) {
+ if (u8_get_bits(map_header->flags, MAP_CMD_FMASK)) {
/* Packet contains a MAP command (not data) */
if (port->data_format & RMNET_FLAGS_INGRESS_MAP_COMMANDS)
return rmnet_map_command(skb, port);
@@ -70,7 +71,7 @@ __rmnet_map_ingress_handler(struct sk_buff *skb,
}
mux_id = map_header->mux_id;
- pad = map_header->pad_len;
+ pad = u8_get_bits(map_header->flags, MAP_PAD_LEN_FMASK);
len = ntohs(map_header->pkt_len) - pad;
if (mux_id >= RMNET_MAX_LOGICAL_EP)
diff --git a/drivers/net/ethernet/qualcomm/rmnet/rmnet_map_data.c
b/drivers/net/ethernet/qualcomm/rmnet/rmnet_map_data.c
index fd55269c2ce3c..3291f252d81b0 100644
--- a/drivers/net/ethernet/qualcomm/rmnet/rmnet_map_data.c
+++ b/drivers/net/ethernet/qualcomm/rmnet/rmnet_map_data.c
@@ -4,6 +4,7 @@
* RMNET Data MAP protocol
*/
+#include <linux/bitfield.h>
#include <linux/netdevice.h>
#include <linux/ip.h>
#include <linux/ipv6.h>
@@ -299,7 +300,8 @@ struct rmnet_map_header *rmnet_map_add_map_header(struct
sk_buff *skb,
done:
map_header->pkt_len = htons(map_datalen + padding);
- map_header->pad_len = padding & 0x3F;
+ /* This is a data packet, so the CMD bit is 0 */
+ map_header->flags = u8_encode_bits(padding, MAP_PAD_LEN_FMASK);
return map_header;
}
diff --git a/include/linux/if_rmnet.h b/include/linux/if_rmnet.h
index 8c7845baf3837..4824c6328a82c 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_*_FMASK */
+ u8 mux_id;
+ __be16 pkt_len; /* Length of packet, including pad */
} __aligned(1);
+/* rmnet_map_header flags field:
+ * CMD: 1 = packet contains a MAP command; 0 = packet contains data
+ * PAD_LEN: number of pad bytes following packet data
+ */
+#define MAP_CMD_FMASK GENMASK(7, 7)
+#define MAP_PAD_LEN_FMASK GENMASK(5, 0)
+
struct rmnet_map_dl_csum_trailer {
u8 reserved1;
#if defined(__LITTLE_ENDIAN_BITFIELD)
--
2.20.1
