CHECK: extern prototypes should be avoided in .h files
#51: FILE: include/linux/mroute6.h:34:
+extern int ip6_mr_output(struct net *net, struct sock *sk, struct sk_buff *skb);

total: 0 errors, 0 warnings, 1 checks, 165 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 ff17b651f5b1 ("net: ipv6: Add ip6_mr_output()") 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, 1 checks, 165 lines checked