checkpatch: correctly track the end of preprocessor commands in context

When looking for a statement we currently run on through preprocessor
commands.  This means that a header file with just definitions is parsed
over and over again combining all of the lines from the current line to
the end of file leading to severe performance issues.

Fix up context accumulation to track preprocessor commands and stop when
reaching the end of them.  At the same time vastly simplify the #define
handling.
Signed-off-by: Andy Whitcroft <apw@canonical.com>
Cc: Joe Perches <joe@perches.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

scripts/checkpatch.pl

@@ -676,6 +676,10 @@ sub ctx_statement_block {
 			if ($off >= $len) {
 				last;
 			}
+			if ($level == 0 && substr($blk, $off) =~ /^.\s*#\s*define/) {
+				$level++;
+				$type = '#';
+			}
 		}
 		$p = $c;
 		$c = substr($blk, $off, 1);
@@ -738,6 +742,13 @@ sub ctx_statement_block {
 				last;
 			}
 		}
+		# Preprocessor commands end at the newline unless escaped.
+		if ($type eq '#' && $c eq "\n" && $p ne "\\") {
+			$level--;
+			$type = '';
+			$off++;
+			last;
+		}
 		$off++;
 	}
 	# We are truly at the end, so shuffle to the next line.
@@ -1801,6 +1812,8 @@ sub process {
 			$stat =~ s/\n./\n /g;
 			$cond =~ s/\n./\n /g;
 
+#print "stat<$stat>\n";
+
 			# Find the real next line.
 			$realline_next = $line_nr_next;
 			if (defined $realline_next &&
@@ -2781,47 +2794,13 @@ sub process {
 			my $cnt = $realcnt;
 			my ($off, $dstat, $dcond, $rest);
 			my $ctx = '';
-
-			my $args = defined($1);
-
-			# Find the end of the macro and limit our statement
-			# search to that.
-			while ($cnt > 0 && defined $lines[$ln - 1] &&
-				$lines[$ln - 1] =~ /^(?:-|..*\\$)/)
-			{
-				$ctx .= $rawlines[$ln - 1] . "\n";
-				$cnt-- if ($lines[$ln - 1] !~ /^-/);
-				$ln++;
-			}
-			$ctx .= $rawlines[$ln - 1];
-
 			($dstat, $dcond, $ln, $cnt, $off) =
-				ctx_statement_block($linenr, $ln - $linenr + 1, 0);
+				ctx_statement_block($linenr, $realcnt, 0);
+			$ctx = $dstat;
 			#print "dstat<$dstat> dcond<$dcond> cnt<$cnt> off<$off>\n";
 			#print "LINE<$lines[$ln-1]> len<" . length($lines[$ln-1]) . "\n";
 
-			# Extract the remainder of the define (if any) and
-			# rip off surrounding spaces, and trailing \'s.
-			$rest = '';
-			while ($off != 0 || ($cnt > 0 && $rest =~ /\\\s*$/)) {
-				#print "ADDING cnt<$cnt> $off <" . substr($lines[$ln - 1], $off) . "> rest<$rest>\n";
-				if ($off != 0 || $lines[$ln - 1] !~ /^-/) {
-					$rest .= substr($lines[$ln - 1], $off) . "\n";
-					$cnt--;
-				}
-				$ln++;
-				$off = 0;
-			}
-			$rest =~ s/\\\n.//g;
-			$rest =~ s/^\s*//s;
-			$rest =~ s/\s*$//s;
-
-			# Clean up the original statement.
-			if ($args) {
-				substr($dstat, 0, length($dcond), '');
-			} else {
-				$dstat =~ s/^.\s*\#\s*define\s+$Ident\s*//;
-			}
+			$dstat =~ s/^.\s*\#\s*define\s+$Ident(?:\([^\)]*\))?\s*//;
 			$dstat =~ s/$;//g;
 			$dstat =~ s/\\\n.//g;
 			$dstat =~ s/^\s*//s;
@@ -2847,23 +2826,32 @@ sub process {
 				^\"|\"$
 			}x;
 			#print "REST<$rest> dstat<$dstat> ctx<$ctx>\n";
-			if ($rest ne '' && $rest ne ',') {
-				if ($rest !~ /while\s*\(/ &&
-				    $dstat !~ /$exceptions/)
-				{
-					ERROR("MULTISTATEMENT_MACRO_USE_DO_WHILE",
-					      "Macros with multiple statements should be enclosed in a do - while loop\n" . "$here\n$ctx\n");
-				}
-
-			} elsif ($ctx !~ /;/) {
 			if ($dstat ne '' &&
-				    $dstat !~ /^(?:$Ident|-?$Constant)$/ &&
+			    $dstat !~ /^(?:$Ident|-?$Constant),$/ &&			# 10, // foo(),
+			    $dstat !~ /^(?:$Ident|-?$Constant);$/ &&			# foo();
+			    $dstat !~ /^(?:$Ident|-?$Constant)$/ &&			# 10 // foo()
 			    $dstat !~ /$exceptions/ &&
-				    $dstat !~ /^\.$Ident\s*=/ &&
-				    $dstat =~ /$Operators/)
+			    $dstat !~ /^\.$Ident\s*=/ &&				# .foo =
+			    $dstat !~ /^do\s*$Constant\s*while\s*$Constant;$/ &&	# do {...} while (...);
+			    $dstat !~ /^for\s*$Constant$/ &&				# for (...)
+			    $dstat !~ /^for\s*$Constant\s+(?:$Ident|-?$Constant)$/ &&	# for (...) bar()
+			    $dstat !~ /^do\s*{/ &&					# do {...
+			    $dstat !~ /^\({/)						# ({...
 			{
+				$ctx =~ s/\n*$//;
+				my $herectx = $here . "\n";
+				my $cnt = statement_rawlines($ctx);
+
+				for (my $n = 0; $n < $cnt; $n++) {
+					$herectx .= raw_line($linenr, $n) . "\n";
+				}
+
+				if ($dstat =~ /;/) {
+					ERROR("MULTISTATEMENT_MACRO_USE_DO_WHILE",
+					      "Macros with multiple statements should be enclosed in a do - while loop\n" . "$herectx");
+				} else {
 					ERROR("COMPLEX_MACRO",
-					      "Macros with complex values should be enclosed in parenthesis\n" . "$here\n$ctx\n");
+					      "Macros with complex values should be enclosed in parenthesis\n" . "$herectx");
 				}
 			}
 		}