Documentation/dev-tools/checkpatch.rst | 13 ++++ scripts/checkpatch.pl | 86 +++++++++++++++++++------- 2 files changed, 78 insertions(+), 21 deletions(-)
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.
A separate --json-pretty flag emits the same JSON in a pretty-printed
(indented, multi-line) form for human reading.
The --json (and --json-pretty) flags are mutually exclusive with
--terse and --emacs. Normal text output behaviour is completely
unchanged when --json is not specified.
Assisted-by: Claude:claude-opus-4-7
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
v3:
- Report the same line numbers text mode prints (matches --emacs
and --showfile). Fixes wrong locations on commit-message issues.
- Drop redundant defined() checks and `+ 0` coercions in the JSON
code; the values are already numeric and always defined.
- Add --json-pretty for indented output.
- Add parens around print() arguments.
- Consolidate the three empty-result early exits into one block.
- Return at the JSON branch instead of wrapping the rest of
process() in an else, so multi-file runs emit one document per
file and the indentation is no longer misleading.
v2: https://lore.kernel.org/all/20260408172435.1268067-1-sashal@kernel.org/
v1: https://lore.kernel.org/all/20260406170039.4034716-1-sashal@kernel.org/
Documentation/dev-tools/checkpatch.rst | 13 ++++
scripts/checkpatch.pl | 86 +++++++++++++++++++-------
2 files changed, 78 insertions(+), 21 deletions(-)
diff --git a/Documentation/dev-tools/checkpatch.rst b/Documentation/dev-tools/checkpatch.rst
index dccede68698ca..8a7c7742b23fa 100644
--- a/Documentation/dev-tools/checkpatch.rst
+++ b/Documentation/dev-tools/checkpatch.rst
@@ -64,6 +64,19 @@ 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.
+ Output is one compact JSON document per input file, suitable for CI
+ and scripted post-processing. Cannot be used with --terse or --emacs.
+
+ - --json-pretty
+
+ Like --json, but emit pretty-printed (indented, multi-line) JSON for
+ human reading.
+
- --showfile
Show the diffed file position instead of the input file position.
diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 0492d6afc9a1f..181bd10b046b7 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -14,6 +14,7 @@ use File::Basename;
use Cwd 'abs_path';
use Term::ANSIColor qw(:constants);
use Encode qw(decode encode);
+use JSON::PP;
my $P = $0;
my $D = dirname(abs_path($P));
@@ -33,6 +34,8 @@ my $chk_patch = 1;
my $tst_only;
my $emacs = 0;
my $terse = 0;
+my $json = 0;
+my $json_pretty = 0;
my $showfile = 0;
my $file = 0;
my $git = 0;
@@ -93,6 +96,8 @@ Options:
--patch treat FILE as patchfile (default)
--emacs emacs compile window format
--terse one line per report
+ --json output results as JSON
+ --json-pretty like --json, but pretty-printed
--showfile emit diffed file position, not input file position
-g, --git treat FILE as a single commit or git revision range
single git commit with:
@@ -320,6 +325,8 @@ GetOptions(
'patch!' => \$chk_patch,
'emacs!' => \$emacs,
'terse!' => \$terse,
+ 'json!' => \$json,
+ 'json-pretty!' => \$json_pretty,
'showfile!' => \$showfile,
'f|file!' => \$file,
'g|git!' => \$git,
@@ -380,6 +387,9 @@ help($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 && $terse);
+$json = 1 if ($json_pretty);
+die "$P: --json cannot be used with --terse or --emacs\n" if ($json && ($terse || $emacs));
+
if ($color =~ /^[01]$/) {
$color = !$color;
} elsif ($color =~ /^always$/i) {
@@ -1352,7 +1362,7 @@ 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";
@@ -1373,7 +1383,7 @@ 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");
@@ -2396,6 +2406,19 @@ sub report {
push(our @report, $output);
+ if ($json) {
+ our ($realfile, $realline, $linenr);
+ my $line = ($file || $showfile) ? $realline : $linenr;
+ my %issue = (
+ level => $level,
+ type => $type,
+ message => $msg,
+ );
+ $issue{file} = $realfile if ($realfile ne '');
+ $issue{line} = $line if ($line);
+ push(our @json_issues, \%issue);
+ }
+
return 1;
}
@@ -2403,6 +2426,24 @@ sub report_dump {
our @report;
}
+sub json_print_result {
+ my ($filename, $total_errors, $total_warnings, $total_checks,
+ $total_lines, $issues, $used_types, $ignored_types) = @_;
+ my %result = (
+ filename => $filename,
+ total_errors => $total_errors,
+ total_warnings => $total_warnings,
+ total_checks => $total_checks,
+ total_lines => $total_lines,
+ issues => $issues,
+ );
+ $result{used_types} = $used_types if (defined $used_types);
+ $result{ignored_types} = $ignored_types if (defined $ignored_types);
+ my $json_encoder = JSON::PP->new->canonical->utf8;
+ $json_encoder->pretty if ($json_pretty);
+ print($json_encoder->encode(\%result), "\n");
+}
+
sub fixup_current_range {
my ($lineRef, $offset, $length) = @_;
@@ -2653,7 +2694,7 @@ sub is_userspace {
sub process {
my $filename = shift;
- my $linenr=0;
+ our $linenr=0;
my $prevline="";
my $prevrawline="";
my $stashline="";
@@ -2691,14 +2732,15 @@ 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 $context_function; #undef'd unless there's a known function
@@ -7806,21 +7848,14 @@ sub process {
}
}
- # If we have no input at all, then there is nothing to report on
- # so just keep quiet.
- if ($#rawlines == -1) {
- exit(0);
- }
-
- # In mailback mode only produce a report in the negative, for
- # things that appear to be patches.
- if ($mailback && ($clean == 1 || !$is_patch)) {
- exit(0);
- }
-
- # This is not a patch, and we are in 'no-patch' mode so
- # just keep quiet.
- if (!$chk_patch && !$is_patch) {
+ # Bail out early without producing a normal report when there is no
+ # input at all, when we are in mailback mode and either the patch is
+ # clean or the input does not appear to be a patch, or when the input
+ # is not a patch and we are in 'no-patch' mode.
+ if ($#rawlines == -1 ||
+ ($mailback && ($clean == 1 || !$is_patch)) ||
+ (!$chk_patch && !$is_patch)) {
+ json_print_result($filename, 0, 0, 0, 0, []) if ($json);
exit(0);
}
@@ -7868,7 +7903,16 @@ sub process {
}
}
- print report_dump();
+ if ($json) {
+ my @used = sort keys %use_type;
+ my @ignored = sort keys %ignore_type;
+ json_print_result($filename, $cnt_error, $cnt_warn,
+ $cnt_chk, $cnt_lines, \@json_issues,
+ \@used, \@ignored);
+ return $clean;
+ }
+
+ print(report_dump());
if ($summary && !($clean == 1 && $quiet == 1)) {
print "$filename " if ($summary_file);
print "total: $cnt_error errors, $cnt_warn warnings, " .
--
2.53.0On Sat, 2026-04-25 at 16:04 -0400, Sasha Levin wrote:
> diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
[]
> @@ -2403,6 +2426,24 @@ sub report_dump {
> our @report;
> }
>
> +sub json_print_result {
> + my ($filename, $total_errors, $total_warnings, $total_checks,
> + $total_lines, $issues, $used_types, $ignored_types) = @_;
> + my %result = (
> + filename => $filename,
> + total_errors => $total_errors,
> + total_warnings => $total_warnings,
> + total_checks => $total_checks,
> + total_lines => $total_lines,
> + issues => $issues,
> + );
> + $result{used_types} = $used_types if (defined $used_types);
> + $result{ignored_types} = $ignored_types if (defined $ignored_types);
> + my $json_encoder = JSON::PP->new->canonical->utf8;
Maybe canonical isn't great as it outputs keys in alphabetic order.
The output may be more sensible in the defined order.
On 2026-04-25 13:04, Sasha Levin wrote: > 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. [] > A separate --json-pretty flag emits the same JSON in a pretty-printed > (indented, multi-line) form for human reading Why not just always use pretty? Would a script care?
On Sat, Apr 25, 2026 at 02:52:35PM -0700, Joe Perches wrote:
>On 2026-04-25 13:04, Sasha Levin wrote:
>>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.
>[]
>>A separate --json-pretty flag emits the same JSON in a pretty-printed
>>(indented, multi-line) form for human reading
>
>Why not just always use pretty?
>Would a script care?
Who's the intended consumer for the --json-pretty?
I my mind, --json is there to make it easier for tooling to process the output.
A user can already achieve the same result by piping the json output through jq
or other similar tools:
$ ./scripts/checkpatch.pl --json 0001-checkpatch-add-json-output-mode.patch
{"filename":"0001-checkpatch-add-json-output-mode.patch","ignored_types":[],"issues":[],"total_checks":0,"total_errors":0,"total_lines":189,"total_warnings":0,"used_types":[]}
$ ./scripts/checkpatch.pl --json 0001-checkpatch-add-json-output-mode.patch | jq
{
"filename": "0001-checkpatch-add-json-output-mode.patch",
"ignored_types": [],
"issues": [],
"total_checks": 0,
"total_errors": 0,
"total_lines": 189,
"total_warnings": 0,
"used_types": []
}
--
Thanks,
Sasha
On Sat, 2026-04-25 at 20:07 -0400, Sasha Levin wrote: > On Sat, Apr 25, 2026 at 02:52:35PM -0700, Joe Perches wrote: > On 2026-04-25 13:04, Sasha Levin wrote: > 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. > > [] > > > A separate --json-pretty flag emits the same JSON in a pretty-printed > > > (indented, multi-line) form for human reading > > Why not just always use pretty? > > Would a script care? > > Who's the intended consumer for the --json-pretty? > > I my mind, --json is there to make it easier for tooling to process the output. Agree, but does the pretty output make it harder for tooling?
On Sat, Apr 25, 2026 at 06:12:13PM -0700, Joe Perches wrote:
>On Sat, 2026-04-25 at 20:07 -0400, Sasha Levin wrote:
>> On Sat, Apr 25, 2026 at 02:52:35PM -0700, Joe Perches wrote:
>> On 2026-04-25 13:04, Sasha Levin wrote:
>> 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.
>> > []
>> > > A separate --json-pretty flag emits the same JSON in a pretty-printed
>> > > (indented, multi-line) form for human reading
>> > Why not just always use pretty?
>> > Would a script care?
>>
>> Who's the intended consumer for the --json-pretty?
>>
>> I my mind, --json is there to make it easier for tooling to process the output.
>
>Agree, but does the pretty output make it harder for tooling?
For real JSON parsers, no - they handle either form fine.
The one issue is multi-file invocations: --json emits one compact document per
file per line (NDJSON), which lets plain-shell consumers do `while read line;
do ...` or pipe through grep/awk/head. Pretty mode loses that property because
each document spans multiple lines, so consumers need a
streaming JSON parser.
--
Thanks,
Sasha
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