checkpatch: add support for Assisted-by tag

The Assisted-by tag was introduced in
Documentation/process/coding-assistants.rst for attributing AI tool
contributions to kernel patches.  However, checkpatch.pl did not recognize
this tag, causing two issues:

  WARNING: Non-standard signature: Assisted-by:
  ERROR: Unrecognized email address: 'AGENT_NAME:MODEL_VERSION'

Fix this by:
1. Adding Assisted-by to the recognized $signature_tags list
2. Skipping email validation for Assisted-by lines since they use the
   AGENT_NAME:MODEL_VERSION format instead of an email address
3. Warning when the Assisted-by value doesn't match the expected format

Link: https://lkml.kernel.org/r/20260311215818.518930-1-sashal@kernel.org
Signed-off-by: Sasha Levin <sashal@kernel.org>
Reported-by: Bart Van Assche <bvanassche@acm.org>
Acked-by: Joe Perches <joe@perches.com>
Cc: Andy Whitcroft <apw@canonical.com>
Cc: Dwaipayan Ray <dwaipayanray1@gmail.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index e56374662ff7973abb2ecf01733ae8c32deccf18..27a43a4d9c4384517c4f90d072e6c71b22c9fa7f 100755 (executable)
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -641,6 +641,7 @@ our $signature_tags = qr{(?xi:
        Reviewed-by:|
        Reported-by:|
        Suggested-by:|
+       Assisted-by:|
        To:|
        Cc:
 )};
@@ -3105,6 +3106,15 @@ sub process {
                                }
                        }
 
+                       # Assisted-by uses AGENT_NAME:MODEL_VERSION format, not email
+                       if ($sign_off =~ /^Assisted-by:/i) {
+                               if ($email !~ /^\S+:\S+/) {
+                                       WARN("BAD_SIGN_OFF",
+                                            "Assisted-by expects 'AGENT_NAME:MODEL_VERSION [TOOL1] [TOOL2]' format\n" . $herecurr);
+                               }
+                               next;
+                       }
+
                        my ($email_name, $name_comment, $email_address, $comment) = parse_email($email);
                        my $suggested_email = format_email(($email_name, $name_comment, $email_address, $comment));
                        if ($suggested_email eq "") {