[Qemu-trivial] [PATCH v3] checkpatch: Flag suspicious attribution lines

[Eric Blake]

Flag commit attribution tags that are unusual (often because they
were a typo), but only as a warning (because sometimes a humorous
or otherwise useful tag is intentionally supplied).

This picks the 6 most popular tags, each with 700 or more uses (well,
S-o-b was already checked for case-sensitivity and typos, leaving
only 5 new tags being checked), as determined by:
$ git log | sed -n 's/^ *\([A-Za-z-]*-[bB][yY]:\).*/\1/p' | \
  sort | uniq -c | sort -k1,1n | tail

Most of the rejected lines were unusual case (48 Reviewed-By), or
obvious typos (among others, we've had 4 cases of someone being
burnt, based on Singed-off-by; and 2 cases of list-reading via an
e-reader, based on eviewed-by); there are also lines forgetting a
space after the ':') or otherwise tongue-in-check (my favorite:
3 Approximately-suggested-by). A few lines not whitelisted here
may be legitimate, but as they are orders of magnitude rarer, it
is therefore not worth worrying about (7 Requested-by,
3 Co-authored-by, 1 Inspired-by, etc.).

Signed-off-by: Eric Blake <address@hidden>

---
v3: also flag *-By [Philippe]
v2: fix regex
---
 scripts/checkpatch.pl | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 88682cb0a9f..e1aef5ba897 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -1456,7 +1456,7 @@ sub process {
                    ERROR("Author email address is mangled by the mailing 
list\n" . $herecurr);
                }

-#check the patch for a signoff:
+#check the patch for a signoff, and that other attribution lines are typical:
                if ($line =~ /^\s*signed-off-by:/i) {
                        # This is a signoff, if ugly, so do not double report.
                        $signoff++;
@@ -1470,6 +1470,10 @@ sub process {
                                ERROR("space required after Signed-off-by:\n" .
                                        $herecurr);
                        }
+               } elsif($line =~ /^\s*([a-z-]*)-by:/i &&
+                       ($1 !~ /(Suggest|Report|Test|Ack|Review)ed/ ||
+                        $line !~ /^\s*[A-Za-z-]*-by:\s/)) {
+                   WARN("suspicious attribution tag:\n" . $herecurr);
                }

 # Check if MAINTAINERS is being updated.  If so, there's probably no need to
-- 
2.20.1