ERROR: Macros with complex values should be enclosed in parentheses
#46: FILE: tools/testing/selftests/drivers/net/hw/nk_forward.bpf.c:13:
+#define ctx_ptr(field)		(void *)(long)(field)

BUT SEE:

   do {} while (0) advice is over-stated in a few situations:

   The more obvious case is macros, like MODULE_PARM_DESC, invoked at
   file-scope, where C disallows code (it must be in functions).  See
   $exceptions if you have one to add by name.

   More troublesome is declarative macros used at top of new scope,
   like DECLARE_PER_CPU.  These might just compile with a do-while-0
   wrapper, but would be incorrect.  Most of these are handled by
   detecting struct,union,etc declaration primitives in $exceptions.

   Theres also macros called inside an if (block), which "return" an
   expression.  These cannot do-while, and need a ({}) wrapper.

   Enjoy this qualification while we work to improve our heuristics.

CHECK: Macro argument 'b' may be better as '(b)' to avoid precedence issues
#48: FILE: tools/testing/selftests/drivers/net/hw/nk_forward.bpf.c:15:
+#define v6_p64_equal(a, b)	(a.s6_addr32[0] == b.s6_addr32[0] && \
+				 a.s6_addr32[1] == b.s6_addr32[1])

WARNING: Use of volatile is usually wrong: see Documentation/process/volatile-considered-harmful.rst
#51: FILE: tools/testing/selftests/drivers/net/hw/nk_forward.bpf.c:18:
+volatile __u32 netkit_ifindex;

WARNING: Use of volatile is usually wrong: see Documentation/process/volatile-considered-harmful.rst
#52: FILE: tools/testing/selftests/drivers/net/hw/nk_forward.bpf.c:19:
+volatile __u8 ipv6_prefix[16];

total: 1 errors, 2 warnings, 1 checks, 54 lines checked

NOTE: For some of the reported defects, checkpatch may be able to
      mechanically convert to the typical style using --fix or --fix-inplace.

Commit ec1603696d55 ("selftests/net: add bpf skb forwarding program") has style problems, please review.

NOTE: Ignored message types: ALLOC_SIZEOF_STRUCT BAD_REPORTED_BY_LINK CAMELCASE COMMIT_LOG_LONG_LINE FILE_PATH_CHANGES GIT_COMMIT_ID MACRO_ARG_REUSE NO_AUTHOR_SIGN_OFF

NOTE: If any of the errors are false positives, please report
      them to the maintainer, see CHECKPATCH in MAINTAINERS.