ERROR: Macros with complex values should be enclosed in parentheses
#78: 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
#80: 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
#83: 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
#84: FILE: tools/testing/selftests/drivers/net/hw/nk_forward.bpf.c:19:
+volatile __u8 ipv6_prefix[16] __attribute__((aligned(4)));

WARNING: Prefer __aligned(4) over __attribute__((aligned(4)))
#84: FILE: tools/testing/selftests/drivers/net/hw/nk_forward.bpf.c:19:
+volatile __u8 ipv6_prefix[16] __attribute__((aligned(4)));

WARNING: line length of 91 exceeds 80 columns
#137: FILE: tools/testing/selftests/drivers/net/hw/nk_forward.c:17:
+static int libbpf_print_fn(enum libbpf_print_level level, const char *format, va_list args)

WARNING: line length of 100 exceeds 80 columns
#144: FILE: tools/testing/selftests/drivers/net/hw/nk_forward.c:24:
+	fprintf(stderr, "Usage: %s -n <netkit_ifindex> -e <eth0_ifindex> -i <ipv6_prefix>\n", prog);

WARNING: line length of 86 exceeds 80 columns
#180: FILE: tools/testing/selftests/drivers/net/hw/nk_forward.c:60:
+		fprintf(stderr, "Error: All options -n, -e, and -i are required\n\n");

WARNING: line length of 82 exceeds 80 columns
#186: FILE: tools/testing/selftests/drivers/net/hw/nk_forward.c:66:
+		fprintf(stderr, "Error: Invalid IPv6 address: %s\n", ipv6_prefix);

WARNING: line length of 84 exceeds 80 columns
#198: FILE: tools/testing/selftests/drivers/net/hw/nk_forward.c:78:
+	memcpy((void *)&skel->bss->ipv6_prefix, &ip6_addr, sizeof(struct in6_addr));

WARNING: line length of 81 exceeds 80 columns
#202: FILE: tools/testing/selftests/drivers/net/hw/nk_forward.c:82:
+		fprintf(stderr, "Error: Failed to load BPF skeleton: %d\n", err);

WARNING: line length of 90 exceeds 80 columns
#207: FILE: tools/testing/selftests/drivers/net/hw/nk_forward.c:87:
+	link = bpf_program__attach_tcx(skel->progs.tc_redirect_peer, eth0_ifindex, &opts);

WARNING: line length of 89 exceeds 80 columns
#210: FILE: tools/testing/selftests/drivers/net/hw/nk_forward.c:90:
+		fprintf(stderr, "Error: Failed to attach TC program to ifindex %u: %s\n",

total: 1 errors, 11 warnings, 1 checks, 174 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 555a1b12ae7e ("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.