[PATCH v2] scripts/checkpatch: more checks on files imported from Linux

[Stefano Garzarella <sgarzare@redhat.com>]

If a file imported from Linux is touched, emit a warning and suggest
using scripts/update-linux-headers.sh.

Also check that updating imported files from Linux are not mixed with
other changes, in which case emit an error.

Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
---
v2:
- added an error when mixing imported files with other changes [Daniel,
  Cornelia]

v1: https://patchew.org/QEMU/20240717093752.50595-1-sgarzare@redhat.com/
---
 scripts/checkpatch.pl | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index ff373a7083..65b6f46f90 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -1374,6 +1374,9 @@ sub process {
 	my $in_header_lines = $file ? 0 : 1;
 	my $in_commit_log = 0;		#Scanning lines before patch
 	my $reported_maintainer_file = 0;
+	my $reported_mixing_imported_file = 0;
+	my $in_imported_file = 0;
+	my $in_no_imported_file = 0;
 	my $non_utf8_charset = 0;
 
 	our @report = ();
@@ -1673,6 +1676,27 @@ sub process {
 # ignore non-hunk lines and lines being removed
 		next if (!$hunk_line || $line =~ /^-/);
 
+# Check that updating imported files from Linux are not mixed with other changes
+		if ($realfile =~ /^(linux-headers|include\/standard-headers)\//) {
+			if (!$in_imported_file) {
+				WARN("added, moved or deleted file(s) " .
+				     "imported from Linux, are you using " .
+				     "scripts/update-linux-headers.sh?\n" .
+				     $herecurr);
+			}
+			$in_imported_file = 1;
+		} else {
+			$in_no_imported_file = 1;
+		}
+
+		if (!$reported_mixing_imported_file &&
+		    $in_imported_file && $in_no_imported_file) {
+			ERROR("headers imported from Linux should be self-" .
+			      "contained in a patch with no other changes\n" .
+			      $herecurr);
+			$reported_mixing_imported_file = 1;
+		}
+
 # ignore files that are being periodically imported from Linux
 		next if ($realfile =~ /^(linux-headers|include\/standard-headers)\//);
 
-- 
2.45.2