[Linux-kernel-mentees] [PATCH] checkpatch: add fix option for MISSING_SIGN_OFF

[Aditya Srivastava]

Currently checkpatch warns us if there is no 'Signed-off-by' line
for the patch.

E.g., running checkpatch on commit 9ac060a708e0 ("leaking_addresses:
Completely remove --version flag") reports this error:

ERROR: Missing Signed-off-by: line(s)

Provide a fix by adding a Signed-off-by line corresponding to the author
of the patch before the patch separator line. Also avoid this error for
the commits where some typo is present in the sign off.

E.g. for commit 8cde5d5f7361 ("bus: ti-sysc: Detect omap4 type timers
for quirk") we get missing sign off as well as bad sign off for:

Siganed-off-by: Tony Lindgren <tony at atomide.com>

Here it is probably best to give BAD_SIGN_OFF warning for Non-standard
signature and avoid MISSING_SIGN_OFF

A quick evaluation over v4.13..v5.8 found out that 4 out of 11 cases
for this error is because of missing sign offs in reverts. Add
documentation regarding it for the future users.

Suggested-by: Joe Perches <joe at perches.com>
Signed-off-by: Aditya Srivastava <yashsri421 at gmail.com>
---
 Documentation/process/submitting-patches.rst |  2 ++
 scripts/checkpatch.pl                        | 17 ++++++++++++++---
 2 files changed, 16 insertions(+), 3 deletions(-)

diff --git a/Documentation/process/submitting-patches.rst b/Documentation/process/submitting-patches.rst
index 83d9a82055a7..ff065e1f6a25 100644
--- a/Documentation/process/submitting-patches.rst
+++ b/Documentation/process/submitting-patches.rst
@@ -404,6 +404,8 @@ then you just add a line saying::
 
 using your real name (sorry, no pseudonyms or anonymous contributions.)
 This will be done for you automatically if you use ``git commit -s``.
+Also reverts should include a Signed-off-by. ``git revert -s`` does
+that for you.
 
 Some people also put extra tags at the end.  They'll just be ignored for
 now, but you can do this to mark internal company procedures or just
diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index cb46288127ac..849e4a510767 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -2404,6 +2404,8 @@ sub process {
 
 	my $last_blank_line = 0;
 	my $last_coalesced_string_linenr = -1;
+	my $patch_separator_linenr = 0;
+	my $is_signed_off = 0;
 
 	our @report = ();
 	our $cnt_lines = 0;
@@ -2755,6 +2757,10 @@ sub process {
 		if ($line =~ /^---$/) {
 			$has_patch_separator = 1;
 			$in_commit_log = 0;
+			# to add missing sign off line before diff(s)
+			if($patch_separator_linenr == 0) {
+				$patch_separator_linenr = $fixlinenr;
+			}
 		}
 
 # Check if MAINTAINERS is being updated.  If so, there's probably no need to
@@ -2771,6 +2777,8 @@ sub process {
 			my $space_after = $3;
 			my $email = $4;
 			my $ucfirst_sign_off = ucfirst(lc($sign_off));
+			# to avoid missing_sign_off error as it most probably is a typo
+			$is_signed_off = 1;
 
 			if ($sign_off !~ /$signature_tags/) {
 				WARN("BAD_SIGN_OFF",
@@ -7118,9 +7126,12 @@ sub process {
 		      "Does not appear to be a unified-diff format patch\n");
 	}
 	if ($is_patch && $has_commit_log && $chk_signoff) {
-		if ($signoff == 0) {
-			ERROR("MISSING_SIGN_OFF",
-			      "Missing Signed-off-by: line(s)\n");
+		if ($signoff == 0 && !$is_signed_off) {
+			if (ERROR("MISSING_SIGN_OFF",
+				  "Missing Signed-off-by: line(s)\n") &&
+			    $fix) {
+				fix_insert_line($patch_separator_linenr, "Signed-off-by: $author");
+			}
 		} elsif ($authorsignoff != 1) {
 			# authorsignoff values:
 			# 0 -> missing sign off
-- 
2.17.1