checkpatch: pull out known acceptable typedefs

Within the type checker we have a number of common kernel types which must
be implemented as typedefs.  Pull those out so that we can use the same
expressions to trigger exclusions.
Signed-off-by: Andy Whitcroft <apw@shadowen.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

scripts/checkpatch.pl

@@ -146,6 +146,11 @@ our $UTF8	= qr {
 	|  \xF4[\x80-\x8F][\x80-\xBF]{2}     # plane 16
 }x;
 
+our $typeTypedefs = qr{(?x:
+	(?:__)?(?:u|s|be|le)(?:\d|\d\d)|
+	atomic_t
+)};
+
 our @typeList = (
 	qr{void},
 	qr{(?:unsigned\s+)?char},
@@ -159,7 +164,6 @@ our @typeList = (
 	qr{float},
 	qr{double},
 	qr{bool},
-	qr{(?:__)?(?:u|s|be|le)(?:\d|\d\d)},
 	qr{struct\s+$Ident},
 	qr{union\s+$Ident},
 	qr{enum\s+$Ident},
@@ -179,6 +183,7 @@ sub build_types {
 			(?:$Modifier\s+|const\s+)*
 			(?:
 				(?:typeof|__typeof__)\s*\(\s*\**\s*$Ident\s*\)|
+				(?:$typeTypedefs\b)|
 				(?:${all}\b)
 			)
 			(?:\s+$Modifier|\s+const)*
@@ -1589,6 +1594,7 @@ sub process {
 		if ($line =~ /\btypedef\s/ &&
 		    $line !~ /\btypedef\s+$Type\s+\(\s*\*?$Ident\s*\)\s*\(/ &&
 		    $line !~ /\btypedef\s+$Type\s+$Ident\s*\(/ &&
+		    $line !~ /\b$typeTypedefs\b/ &&
 		    $line !~ /\b__bitwise(?:__|)\b/) {
 			WARN("do not add new typedefs\n" . $herecurr);
 		}