checkpatch: improve macro reuse test

checkpatch reports a false positive when using token pasting argument
multiple times in a macro.

Fix it.

Miscellanea:

o Make the $tmp variable name used in the macro argument tests
  a bit more descriptive

Link: http://lkml.kernel.org/r/cf434ae7602838388c7cb49d42bca93ab88527e7.1498483044.git.joe@perches.com
Signed-off-by: Joe Perches <joe@perches.com>
Reported-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 63409db..43171ed 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -4940,17 +4940,17 @@
 			foreach my $arg (@def_args) {
 			        next if ($arg =~ /\.\.\./);
 			        next if ($arg =~ /^type$/i);
-				my $tmp = $define_stmt;
-				$tmp =~ s/\b(typeof|__typeof__|__builtin\w+|typecheck\s*\(\s*$Type\s*,|\#+)\s*\(*\s*$arg\s*\)*\b//g;
-				$tmp =~ s/\#+\s*$arg\b//g;
-				$tmp =~ s/\b$arg\s*\#\#//g;
-				my $use_cnt = $tmp =~ s/\b$arg\b//g;
+				my $tmp_stmt = $define_stmt;
+				$tmp_stmt =~ s/\b(typeof|__typeof__|__builtin\w+|typecheck\s*\(\s*$Type\s*,|\#+)\s*\(*\s*$arg\s*\)*\b//g;
+				$tmp_stmt =~ s/\#+\s*$arg\b//g;
+				$tmp_stmt =~ s/\b$arg\s*\#\#//g;
+				my $use_cnt = $tmp_stmt =~ s/\b$arg\b//g;
 				if ($use_cnt > 1) {
 					CHK("MACRO_ARG_REUSE",
 					    "Macro argument reuse '$arg' - possible side-effects?\n" . "$herectx");
 				    }
 # check if any macro arguments may have other precedence issues
-				if ($define_stmt =~ m/($Operators)?\s*\b$arg\b\s*($Operators)?/m &&
+				if ($tmp_stmt =~ m/($Operators)?\s*\b$arg\b\s*($Operators)?/m &&
 				    ((defined($1) && $1 ne ',') ||
 				     (defined($2) && $2 ne ','))) {
 					CHK("MACRO_ARG_PRECEDENCE",