checkpatch: try to avoid poor patch subject lines

Naming the tool that found an issue in the subject line isn't very useful.
 Emit a warning when a common tool (currently checkpatch, sparse or
smatch) is in the subject line.
Signed-off-by: Joe Perches <joe@perches.com>
Suggested-by: Al Viro <viro@ZenIV.linux.org.uk>
Acked-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

scripts/checkpatch.pl

@@ -2170,6 +2170,13 @@ sub process {
 			}
 		}
 
+# Check email subject for common tools that don't need to be mentioned
+		if ($in_header_lines &&
+		    $line =~ /^Subject:.*\b(?:checkpatch|sparse|smatch)\b[^:]/i) {
+			WARN("EMAIL_SUBJECT",
+			     "A patch subject line should describe the change not the tool that found it\n" . $herecurr);
+		}
+
 # Check for old stable address
 		if ($line =~ /^\s*cc:\s*.*<?\bstable\@kernel\.org\b>?.*$/i) {
 			ERROR("STABLE_ADDRESS",