CHECK: Macro argument 'ihl' may be better as '(ihl)' to avoid precedence issues
#28: FILE: include/net/ip.h:41:
+#define IPV4_HEADER_LEN(ihl)    (ihl << 2)

WARNING: line length of 99 exceeds 80 columns
#51: FILE: net/ipv4/ah4.c:137:
+		memcpy(top_iph + 1, iph + 1, IPV4_HEADER_LEN(top_iph->ihl) - sizeof(struct iphdr));

WARNING: line length of 99 exceeds 80 columns
#60: FILE: net/ipv4/ah4.c:197:
+		memcpy(iph + 1, top_iph + 1, IPV4_HEADER_LEN(top_iph->ihl) - sizeof(struct iphdr));

WARNING: line length of 99 exceeds 80 columns
#69: FILE: net/ipv4/ah4.c:253:
+		memcpy(top_iph + 1, iph + 1, IPV4_HEADER_LEN(top_iph->ihl) - sizeof(struct iphdr));

WARNING: line length of 87 exceeds 80 columns
#82: FILE: net/ipv4/cipso_ipv4.c:1504:
+	for (optlen = IPV4_HEADER_LEN(iph->ihl) - sizeof(struct iphdr); optlen > 1; ) {

total: 0 errors, 4 warnings, 1 checks, 100 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 938f1593d994 ("net:ipv4: Use shift left 2 to calculate the length of the IPv4 header.") has style problems, please review.

NOTE: Ignored message types: ALLOC_SIZEOF_STRUCT BAD_REPORTED_BY_LINK CAMELCASE COMMIT_LOG_LONG_LINE 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.
total: 0 errors, 4 warnings, 1 checks, 100 lines checked