checkpatch: improve the unnecessary initialisers tests

Global and static variables don't need to be initialized to 0.

There is already a test for this but the output message doesn't
mention booleans initialized to false.

Improve the output message and the test by adding various forms
with possible specific integer types and possible multiple zeros.

Miscellanea:

o Use a variable to hold the possible 0 test
Signed-off-by: NJoe Perches <joe@perches.com>
Signed-off-by: NShailendra Verma <shailendra.v@samsung.com>
Tested-by: NShailendra Verma <shailendra.v@samsung.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

scripts/checkpatch.pl

@@ -370,6 +370,8 @@ our $typeTypedefs = qr{(?x:
 	$typeKernelTypedefs\b
 )};
 
+our $zero_initializer = qr{(?:(?:0[xX])?0+$Int_type?|NULL|false)\b};
+
 our $logFunctions = qr{(?x:
 	printk(?:_ratelimited|_once|)|
 	(?:[a-z0-9]+_){1,2}(?:printk|emerg|alert|crit|err|warning|warn|notice|info|debug|dbg|vdbg|devel|cont|WARN)(?:_ratelimited|_once|)|
@@ -3334,21 +3336,20 @@ sub process {
 		}
 
 # check for global initialisers.
-		if ($line =~ /^\+$Type\s*$Ident(?:\s+$Modifier)*\s*=\s*(?:0|NULL|false)\s*;/) {
+		if ($line =~ /^\+$Type\s*$Ident(?:\s+$Modifier)*\s*=\s*($zero_initializer)\s*;/) {
 			if (ERROR("GLOBAL_INITIALISERS",
-				  "do not initialise globals to 0 or NULL\n" .
-				      $herecurr) &&
+				  "do not initialise globals to $1\n" . $herecurr) &&
 			    $fix) {
-				$fixed[$fixlinenr] =~ s/(^.$Type\s*$Ident(?:\s+$Modifier)*)\s*=\s*(0|NULL|false)\s*;/$1;/;
+				$fixed[$fixlinenr] =~ s/(^.$Type\s*$Ident(?:\s+$Modifier)*)\s*=\s*$zero_initializer\s*;/$1;/;
 			}
 		}
 # check for static initialisers.
-		if ($line =~ /^\+.*\bstatic\s.*=\s*(0|NULL|false)\s*;/) {
+		if ($line =~ /^\+.*\bstatic\s.*=\s*($zero_initializer)\s*;/) {
 			if (ERROR("INITIALISED_STATIC",
-				  "do not initialise statics to 0 or NULL\n" .
+				  "do not initialise statics to $1\n" .
 				      $herecurr) &&
 			    $fix) {
-				$fixed[$fixlinenr] =~ s/(\bstatic\s.*?)\s*=\s*(0|NULL|false)\s*;/$1;/;
+				$fixed[$fixlinenr] =~ s/(\bstatic\s.*?)\s*=\s*$zero_initializer\s*;/$1;/;
 			}
 		}