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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>
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9d131d044f
commit
16653c16d2
3 changed files with 15 additions and 16 deletions
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@ -61,7 +61,7 @@ __rmnet_map_ingress_handler(struct sk_buff *skb,
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u16 len, pad;
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u8 mux_id;
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if (map_header->cd_bit) {
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if (map_header->flags & MAP_CMD_FLAG) {
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/* Packet contains a MAP command (not data) */
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if (port->data_format & RMNET_FLAGS_INGRESS_MAP_COMMANDS)
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return rmnet_map_command(skb, port);
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@ -70,7 +70,7 @@ __rmnet_map_ingress_handler(struct sk_buff *skb,
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}
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mux_id = map_header->mux_id;
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pad = map_header->pad_len;
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pad = map_header->flags & MAP_PAD_LEN_MASK;
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len = ntohs(map_header->pkt_len) - pad;
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if (mux_id >= RMNET_MAX_LOGICAL_EP)
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@ -280,6 +280,7 @@ struct rmnet_map_header *rmnet_map_add_map_header(struct sk_buff *skb,
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return map_header;
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}
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BUILD_BUG_ON(MAP_PAD_LEN_MASK < 3);
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padding = ALIGN(map_datalen, 4) - map_datalen;
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if (padding == 0)
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@ -293,7 +294,8 @@ struct rmnet_map_header *rmnet_map_add_map_header(struct sk_buff *skb,
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done:
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map_header->pkt_len = htons(map_datalen + padding);
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map_header->pad_len = padding & 0x3F;
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/* This is a data packet, so the CMD bit is 0 */
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map_header->flags = padding & MAP_PAD_LEN_MASK;
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return map_header;
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}
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@ -6,21 +6,18 @@
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#define _LINUX_IF_RMNET_H_
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struct rmnet_map_header {
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#if defined(__LITTLE_ENDIAN_BITFIELD)
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u8 pad_len:6;
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u8 reserved_bit:1;
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u8 cd_bit:1;
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#elif defined (__BIG_ENDIAN_BITFIELD)
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u8 cd_bit:1;
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u8 reserved_bit:1;
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u8 pad_len:6;
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#else
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#error "Please fix <asm/byteorder.h>"
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#endif
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u8 mux_id;
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__be16 pkt_len;
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u8 flags; /* MAP_CMD_FLAG, MAP_PAD_LEN_MASK */
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u8 mux_id;
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__be16 pkt_len; /* Length of packet, including pad */
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} __aligned(1);
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/* rmnet_map_header flags field:
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* PAD_LEN: number of pad bytes following packet data
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* CMD: 1 = packet contains a MAP command; 0 = packet contains data
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*/
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#define MAP_PAD_LEN_MASK GENMASK(5, 0)
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#define MAP_CMD_FLAG BIT(7)
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struct rmnet_map_dl_csum_trailer {
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u8 reserved1;
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#if defined(__LITTLE_ENDIAN_BITFIELD)
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