CHECK: Macro argument 'in_dev' may be better as '(in_dev)' to avoid precedence issues
#33: FILE: include/linux/igmp.h:145:
+#define for_each_pmc_rcu(in_dev, pmc)				\
+	for (pmc = rcu_dereference(in_dev->mc_list);		\
+	     pmc != NULL;					\
+	     pmc = rcu_dereference(pmc->next_rcu))

CHECK: Comparison to NULL could be written "pmc"
#35: FILE: include/linux/igmp.h:147:
+	     pmc != NULL;					\

total: 0 errors, 0 warnings, 2 checks, 159 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 7f99494263d3 ("netlink: support dumping IPv4 multicast addresses") 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, 0 warnings, 2 checks, 159 lines checked