Re: [PATCH net 1/1] uapi: fix big endian definition of ipv6_rpl_sr_hdr

On 1/25/21 12:32 PM, Jakub Kicinski wrote:

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diff --git a/include/uapi/linux/rpl.h b/include/uapi/linux/rpl.h
index 1dccb55cf8c6..708adddf9f13 100644
--- a/include/uapi/linux/rpl.h
+++ b/include/uapi/linux/rpl.h

@@ -28,10 +28,10 @@ struct ipv6_rpl_sr_hdr {
 		pad:4,
 		reserved1:16;
 #elif defined(__BIG_ENDIAN_BITFIELD)
-	__u32	reserved:20,
+	__u32	cmpri:4,
+		cmpre:4,
 		pad:4,
-		cmpri:4,
-		cmpre:4;
+		reserved:20;
 #else
 #error  "Please fix <asm/byteorder.h>"
 #endif  

cross-checking with other headers - tcp and vxlan-gpe - this patch looks
correct.

What are you cross-checking?

https://tools.ietf.org/html/draft-ietf-nvo3-vxlan-gpe-10, Section 3.1
header definition and vxlanhdr_gpe in include/net/vxlan.h. The
__BIG_ENDIAN_BITFIELD part follows the definition in the spec.

Similarly for the TCP header - RFC header definition and tcphdr in
include/uapi/linux/tcp.h. TCP header shows doff + res1 order which is
comparable to cmpri + cpmre in this header as both sets are 4-bits and
start a word.