[PATCH] checkpatch: add --json output mode

Sasha Levin
2026-04-06T17:00:43Z

Add a --json flag to checkpatch.pl that emits structured JSON output,
making results machine-parseable for CI systems, IDE integrations, and
AI-assisted code review tools.

The JSON output includes per-file totals (errors, warnings, checks,
lines) and an array of individual issues with structured fields for
level, type, message, file path, and line number.

The --json flag is mutually exclusive with --terse and --emacs.
Normal text output behavior is completely unchanged when --json is
not specified.

Assisted-by: Claude:claude-opus-4-6
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
Documentation/dev-tools/checkpatch.rst | 7 +++
scripts/checkpatch.pl | 86 ++++++++++++++++++++++++--
2 files changed, 87 insertions(+), 6 deletions(-)

diff --git a/Documentation/dev-tools/checkpatch.rst b/Documentation/dev-tools/checkpatch.rst
index dccede68698ca..17e5744d3dee6 100644
--- a/Documentation/dev-tools/checkpatch.rst
+++ b/Documentation/dev-tools/checkpatch.rst
@@ -64,6 +64,13 @@ Available options:

Output only one line per report.

+ - --json
+
+ Output results as a JSON object. The object includes total error, warning,
+ and check counts, plus an array of individual issues with structured fields
+ for level, type, message, file, and line number. Cannot be used with
+ --terse or --emacs.
+
- --showfile

Show the diffed file position instead of the input file position.
diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index e56374662ff79..ed70753ba1afc 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -33,6 +33,7 @@ my $chk_patch = 1;
my $tst_only;
my $emacs = 0;
my $terse = 0;
+my $json = 0;
my $showfile = 0;
my $file = 0;
my $git = 0;
@@ -93,6 +94,7 @@ Options:
--patch treat FILE as patchfile (default)
--emacs emacs compile window format
--terse one line per report
+ --json output results as JSON
--showfile emit diffed file position, not input file position
-g, --git treat FILE as a single commit or git revision range
single git commit with:
@@ -320,6 +322,7 @@ GetOptions(
'patch!' => \$chk_patch,
'emacs!' => \$emacs,
'terse!' => \$terse,
+ 'json!' => \$json,
'showfile!' => \$showfile,
'f|file!' => \$file,
'g|git!' => \$git,
@@ -379,6 +382,7 @@ help($help - 1) if ($help);

die "$P: --git cannot be used with --file or --fix\n" if ($git && ($file || $fix));
die "$P: --verbose cannot be used with --terse\n" if ($verbose && $terse);
+die "$P: --json cannot be used with --terse or --emacs\n" if ($json && ($terse || $emacs));

if ($color =~ /^[01]$/) {
$color = !$color;
@@ -1351,7 +1355,7 @@ for my $filename (@ARGV) {
}
close($FILE);

- if ($#ARGV > 0 && $quiet == 0) {
+ if (!$json && $#ARGV > 0 && $quiet == 0) {
print '-' x length($vname) . "\n";
print "$vname\n";
print '-' x length($vname) . "\n";
@@ -1372,7 +1376,7 @@ for my $filename (@ARGV) {
$file = $oldfile if ($is_git_file);
}

-if (!$quiet) {
+if (!$quiet && !$json) {
hash_show_words(\%use_type, "Used");
hash_show_words(\%ignore_type, "Ignored");

@@ -2395,6 +2399,18 @@ sub report {

push(our @report, $output);

+ if ($json) {
+ our ($realfile, $realline);
+ my %issue = (
+ level => $level,
+ type => $type,
+ message => $msg,
+ );
+ $issue{file} = $realfile if (defined $realfile && $realfile ne '');
+ $issue{line} = $realline + 0 if (defined $realline && $realline);
+ push(our @json_issues, \%issue);
+ }
+
return 1;
}

@@ -2402,6 +2418,34 @@ sub report_dump {
our @report;
}

+sub json_escape {
+ my ($str) = @_;
+ $str =~ s/\\/\\\\/g;
+ $str =~ s/"/\\"/g;
+ $str =~ s/\n/\\n/g;
+ $str =~ s/\r/\\r/g;
+ $str =~ s/\t/\\t/g;
+ $str =~ s/\x08/\\b/g;
+ $str =~ s/\x0c/\\f/g;
+ $str =~ s/([\x00-\x07\x0b\x0e-\x1f])/sprintf("\\u%04x", ord($1))/ge;
+ return $str;
+}
+
+sub json_encode_issue {
+ my ($issue) = @_;
+ my @fields;
+ push(@fields, '"level":"' . json_escape($issue->{level}) . '"');
+ push(@fields, '"type":"' . json_escape($issue->{type}) . '"');
+ push(@fields, '"message":"' . json_escape($issue->{message}) . '"');
+ if (defined $issue->{file}) {
+ push(@fields, '"file":"' . json_escape($issue->{file}) . '"');
+ }
+ if (defined $issue->{line}) {
+ push(@fields, '"line":' . ($issue->{line} + 0));
+ }
+ return '{' . join(',', @fields) . '}';
+}
+
sub fixup_current_range {
my ($lineRef, $offset, $length) = @_;

@@ -2690,14 +2734,15 @@ sub process {
my $last_coalesced_string_linenr = -1;

our @report = ();
+ our @json_issues = ();
our $cnt_lines = 0;
our $cnt_error = 0;
our $cnt_warn = 0;
our $cnt_chk = 0;

# Trace the real file/line as we go.
- my $realfile = '';
- my $realline = 0;
+ our $realfile = '';
+ our $realline = 0;
my $realcnt = 0;
my $here = '';
my $context_function; #undef'd unless there's a known function
@@ -7791,18 +7836,33 @@ sub process {
# If we have no input at all, then there is nothing to report on
# so just keep quiet.
if ($#rawlines == -1) {
+ if ($json) {
+ print '{"filename":"' . json_escape($filename) .
+ '","total_errors":0,"total_warnings":0,' .
+ '"total_checks":0,"total_lines":0,"issues":[]}' . "\n";
+ }
exit(0);
}

# In mailback mode only produce a report in the negative, for
# things that appear to be patches.
if ($mailback && ($clean == 1 || !$is_patch)) {
+ if ($json) {
+ print '{"filename":"' . json_escape($filename) .
+ '","total_errors":0,"total_warnings":0,' .
+ '"total_checks":0,"total_lines":0,"issues":[]}' . "\n";
+ }
exit(0);
}

# This is not a patch, and we are in 'no-patch' mode so
# just keep quiet.
if (!$chk_patch && !$is_patch) {
+ if ($json) {
+ print '{"filename":"' . json_escape($filename) .
+ '","total_errors":0,"total_warnings":0,' .
+ '"total_checks":0,"total_lines":0,"issues":[]}' . "\n";
+ }
exit(0);
}

@@ -7850,6 +7910,19 @@ sub process {
}
}

+ if ($json) {
+ my @issue_strings;
+ foreach my $issue (@json_issues) {
+ push(@issue_strings, json_encode_issue($issue));
+ }
+ print '{"filename":"' . json_escape($filename) . '",' .
+ '"total_errors":' . ($cnt_error + 0) . ',' .
+ '"total_warnings":' . ($cnt_warn + 0) . ',' .
+ '"total_checks":' . ($cnt_chk + 0) . ',' .
+ '"total_lines":' . ($cnt_lines + 0) . ',' .
+ '"issues":[' . join(',', @issue_strings) . ']' .
+ '}' . "\n";
+ } else {
print report_dump();
if ($summary && !($clean == 1 && $quiet == 1)) {
print "$filename " if ($summary_file);
@@ -7878,8 +7951,9 @@ NOTE: Whitespace errors detected.
EOM
}
}
+ } # end !$json

- if ($clean == 0 && $fix &&
+ if (!$json && $clean == 0 && $fix &&
("@rawlines" ne "@fixed" ||
$#fixed_inserted >= 0 || $#fixed_deleted >= 0)) {
my $newfile = $filename;
@@ -7918,7 +7992,7 @@ EOM
}
}

- if ($quiet == 0) {
+ if (!$json && $quiet == 0) {
print "\n";
if ($clean == 1) {
print "$vname has no obvious style problems and is ready for submission.\n";
--
2.53.0