checkpatch: emit a warning on embedded filenames

Embedding the complete filename path inside the file isn't particularly
useful as often the path is moved around and becomes incorrect.

Emit a warning when the source contains the filename.

[akpm@linux-foundation.org: remove stray " di"]

Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Link: https://lkml.kernel.org/r/1fd5f9188a14acdca703ca00301ee323de672a8d.camel@perches.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

scripts/checkpatch.pl

@@ -3271,6 +3271,12 @@ sub process {
 			}
 		}
 
+# check for embedded filenames
+		if ($rawline =~ /^\+.*\Q$realfile\E/) {
+			WARN("EMBEDDED_FILENAME",
+			     "It's generally not useful to have the filename in the file\n" . $herecurr);
+		}
+
 # check we are in a valid source file if not then ignore this hunk
 		next if ($realfile !~ /\.(h|c|s|S|sh|dtsi|dts)$/);