checkpatch.pl

		if ($rawline =~ m{^.#\s*include\s+[<"](.*)[">]}) {
			my $path = $1;
			if ($path =~ m{//}) {
				ERROR("malformed #include filename\n" .
					$herecurr);
			}
			# Sanitise this special form of string.
			$path = 'X' x length($path);
			$line =~ s{\<.*\>}{<$path>};
		}

# no C99 // comments
		if ($line =~ m{//}) {
			ERROR("do not use C99 // comments\n" . $herecurr);
		}
		# Remove C99 comments.
		$line =~ s@//.*@@;
		$opline =~ s@//.*@@;

#EXPORT_SYMBOL should immediately follow its function closing }.
		if (($line =~ /EXPORT_SYMBOL.*\((.*)\)/) ||
		    ($line =~ /EXPORT_UNUSED_SYMBOL.*\((.*)\)/)) {
			my $name = $1;
			if (($prevline !~ /^}/) &&
			   ($prevline !~ /^\+}/) &&
			   ($prevline !~ /^ }/) &&
			   ($prevline !~ /\b\Q$name\E(?:\s+$Attribute)?\s*(?:;|=)/)) {
				WARN("EXPORT_SYMBOL(foo); should immediately follow its function/variable\n" . $herecurr);
			}
		}

# check for external initialisers.
		if ($line =~ /^.$Type\s*$Ident\s*=\s*(0|NULL);/) {
			ERROR("do not initialise externals to 0 or NULL\n" .
				$herecurr);
		}
# check for static initialisers.
		if ($line =~ /\s*static\s.*=\s*(0|NULL);/) {
			ERROR("do not initialise statics to 0 or NULL\n" .
				$herecurr);
		}

# check for new typedefs, only function parameters and sparse annotations
# make sense.
		if ($line =~ /\btypedef\s/ &&
		    $line !~ /\btypedef\s+$Type\s+\(\s*\*?$Ident\s*\)\s*\(/ &&
		    $line !~ /\b__bitwise(?:__|)\b/) {
			WARN("do not add new typedefs\n" . $herecurr);
		}

# * goes on variable not on type
		if ($line =~ m{\($NonptrType(\*+)(?:\s+const)?\)}) {
			ERROR("\"(foo$1)\" should be \"(foo $1)\"\n" .
				$herecurr);

		} elsif ($line =~ m{\($NonptrType\s+(\*+)(?!\s+const)\s+\)}) {
			ERROR("\"(foo $1 )\" should be \"(foo $1)\"\n" .
				$herecurr);

		} elsif ($line =~ m{$NonptrType(\*+)(?:\s+(?:$Attribute|$Sparse))?\s+[A-Za-z\d_]+}) {
			ERROR("\"foo$1 bar\" should be \"foo $1bar\"\n" .
				$herecurr);

		} elsif ($line =~ m{$NonptrType\s+(\*+)(?!\s+(?:$Attribute|$Sparse))\s+[A-Za-z\d_]+}) {
			ERROR("\"foo $1 bar\" should be \"foo $1bar\"\n" .
				$herecurr);
		}

# # no BUG() or BUG_ON()
# 		if ($line =~ /\b(BUG|BUG_ON)\b/) {
# 			print "Try to use WARN_ON & Recovery code rather than BUG() or BUG_ON()\n";
# 			print "$herecurr";
# 			$clean = 0;
# 		}

		if ($line =~ /\bLINUX_VERSION_CODE\b/) {
			WARN("LINUX_VERSION_CODE should be avoided, code should be for the version to which it is merged" . $herecurr);
		}

# printk should use KERN_* levels.  Note that follow on printk's on the
# same line do not need a level, so we use the current block context
# to try and find and validate the current printk.  In summary the current
# printk includes all preceeding printk's which have no newline on the end.
# we assume the first bad printk is the one to report.
		if ($line =~ /\bprintk\((?!KERN_)\s*"/) {
			my $ok = 0;
			for (my $ln = $linenr - 1; $ln >= $first_line; $ln--) {
				#print "CHECK<$lines[$ln - 1]\n";
				# we have a preceeding printk if it ends
				# with "\n" ignore it, else it is to blame
				if ($lines[$ln - 1] =~ m{\bprintk\(}) {
					if ($rawlines[$ln - 1] !~ m{\\n"}) {
						$ok = 1;
					}
					last;
				}
			}
			if ($ok == 0) {
				WARN("printk() should include KERN_ facility level\n" . $herecurr);
			}
		}

# function brace can't be on same line, except for #defines of do while,
# or if closed on same line
		if (($line=~/$Type\s*[A-Za-z\d_]+\(.*\).* {/) and
		    !($line=~/\#define.*do\s{/) and !($line=~/}/)) {
			ERROR("open brace '{' following function declarations go on the next line\n" . $herecurr);
		}

# open braces for enum, union and struct go on the same line.
		if ($line =~ /^.\s*{/ &&
		    $prevline =~ /^.\s*(?:typedef\s+)?(enum|union|struct)(?:\s+$Ident)?\s*$/) {
			ERROR("open brace '{' following $1 go on the same line\n" . $hereprev);
		}

# check for spaces between functions and their parentheses.
		while ($line =~ /($Ident)\s+\(/g) {
			if ($1 !~ /^(?:if|for|while|switch|return|volatile|__volatile__|__attribute__|format|__extension__|Copyright|case)$/ &&
		            $line !~ /$Type\s+\(/ && $line !~ /^.\#\s*define\b/) {
				WARN("no space between function name and open parenthesis '('\n" . $herecurr);
			}
		}
# Check operator spacing.
		if (!($line=~/\#\s*include/)) {
			my $ops = qr{
				<<=|>>=|<=|>=|==|!=|
				\+=|-=|\*=|\/=|%=|\^=|\|=|&=|
				=>|->|<<|>>|<|>|=|!|~|
				&&|\|\||,|\^|\+\+|--|&|\||\+|-|\*|\/
			}x;
			my @elements = split(/($ops|;)/, $opline);
			my $off = 0;

			my $blank = copy_spacing($opline);

			for (my $n = 0; $n < $#elements; $n += 2) {
				$off += length($elements[$n]);

				my $a = '';
				$a = 'V' if ($elements[$n] ne '');
				$a = 'W' if ($elements[$n] =~ /\s$/);
				$a = 'B' if ($elements[$n] =~ /(\[|\()$/);
				$a = 'O' if ($elements[$n] eq '');
				$a = 'E' if ($elements[$n] eq '' && $n == 0);

				my $op = $elements[$n + 1];

				my $c = '';
				if (defined $elements[$n + 2]) {
					$c = 'V' if ($elements[$n + 2] ne '');
					$c = 'W' if ($elements[$n + 2] =~ /^\s/);
					$c = 'B' if ($elements[$n + 2] =~ /^(\)|\]|;)/);
					$c = 'O' if ($elements[$n + 2] eq '');
					$c = 'E' if ($elements[$n + 2] =~ /\s*\\$/);
				} else {
					$c = 'E';
				}

				# Pick up the preceeding and succeeding characters.
				my $ca = substr($opline, 0, $off);
				my $cc = '';
				if (length($opline) >= ($off + length($elements[$n + 1]))) {
					$cc = substr($opline, $off + length($elements[$n + 1]));
				}
				my $cb = "$ca$;$cc";

				my $ctx = "${a}x${c}";

				my $at = "(ctx:$ctx)";

				my $ptr = substr($blank, 0, $off) . "^";
				my $hereptr = "$hereline$ptr\n";

				# Classify operators into binary, unary, or
				# definitions (* only) where they have more
				# than one mode.
				my $op_type = substr($curr_values, $off + 1, 1);
				my $op_left = substr($curr_values, $off, 1);
				my $is_unary;
				if ($op_type eq 'T') {
					$is_unary = 2;
				} elsif ($op_left eq 'V') {
					$is_unary = 0;
				} else {
					$is_unary = 1;
				}
				#if ($op eq '-' || $op eq '&' || $op eq '*') {
				#	print "UNARY: <$op_left$op_type $is_unary $a:$op:$c> <$ca:$op:$cc> <$unary_ctx>\n";
				#}

				# ; should have either the end of line or a space or \ after it
				if ($op eq ';') {
					if ($ctx !~ /.x[WEB]/ && $cc !~ /^\\/ &&
					    $cc !~ /^;/) {
						ERROR("need space after that '$op' $at\n" . $hereptr);
					}

				# // is a comment
				} elsif ($op eq '//') {

				# -> should have no spaces
				} elsif ($op eq '->') {
					if ($ctx =~ /Wx.|.xW/) {
						ERROR("no spaces around that '$op' $at\n" . $hereptr);
					}

				# , must have a space on the right.
				} elsif ($op eq ',') {
					if ($ctx !~ /.xW|.xE/ && $cc !~ /^}/) {
						ERROR("need space after that '$op' $at\n" . $hereptr);
					}

				# '*' as part of a type definition -- reported already.
				} elsif ($op eq '*' && $is_unary == 2) {
					#warn "'*' is part of type\n";

				# unary operators should have a space before and
				# none after.  May be left adjacent to another
				# unary operator, or a cast
				} elsif ($op eq '!' || $op eq '~' ||
				         ($is_unary && ($op eq '*' || $op eq '-' || $op eq '&'))) {
					if ($ctx !~ /[WEB]x./ && $ca !~ /(?:\)|!|~|\*|-|\&|\||\+\+|\-\-|\{)$/) {
						ERROR("need space before that '$op' $at\n" . $hereptr);
					}
					if ($ctx =~ /.xW/) {
						ERROR("no space after that '$op' $at\n" . $hereptr);
					}

				# unary ++ and unary -- are allowed no space on one side.
				} elsif ($op eq '++' or $op eq '--') {
					if ($ctx !~ /[WOB]x[^W]/ && $ctx !~ /[^W]x[WOBE]/) {
						ERROR("need space one side of that '$op' $at\n" . $hereptr);
					}
					if ($ctx =~ /Wx./ && $cc =~ /^;/) {
						ERROR("no space before that '$op' $at\n" . $hereptr);
					}

				# << and >> may either have or not have spaces both sides
				} elsif ($op eq '<<' or $op eq '>>' or
					 $op eq '&' or $op eq '^' or $op eq '|' or
					 $op eq '+' or $op eq '-' or
					 $op eq '*' or $op eq '/')
				{
					if ($ctx !~ /VxV|WxW|VxE|WxE|VxO/) {
						ERROR("need consistent spacing around '$op' $at\n" .
							$hereptr);
					}

				# All the others need spaces both sides.
				} elsif ($ctx !~ /[EW]x[WE]/) {
					# Ignore email addresses <foo@bar>
					if (!($op eq '<' && $cb =~ /$;\S+\@\S+>/) &&
					    !($op eq '>' && $cb =~ /<\S+\@\S+$;/)) {
						ERROR("need spaces around that '$op' $at\n" . $hereptr);
					}
				}
				$off += length($elements[$n + 1]);
			}
		}

# check for multiple assignments
		if ($line =~ /^.\s*$Lval\s*=\s*$Lval\s*=(?!=)/) {
			CHK("multiple assignments should be avoided\n" . $herecurr);
		}

## # check for multiple declarations, allowing for a function declaration
## # continuation.
## 		if ($line =~ /^.\s*$Type\s+$Ident(?:\s*=[^,{]*)?\s*,\s*$Ident.*/ &&
## 		    $line !~ /^.\s*$Type\s+$Ident(?:\s*=[^,{]*)?\s*,\s*$Type\s*$Ident.*/) {
##
## 			# Remove any bracketed sections to ensure we do not
## 			# falsly report the parameters of functions.
## 			my $ln = $line;
## 			while ($ln =~ s/\([^\(\)]*\)//g) {
## 			}
## 			if ($ln =~ /,/) {
## 				WARN("declaring multiple variables together should be avoided\n" . $herecurr);
## 			}
## 		}

#need space before brace following if, while, etc
		if (($line =~ /\(.*\){/ && $line !~ /\($Type\){/) ||
		    $line =~ /do{/) {
			ERROR("need a space before the open brace '{'\n" . $herecurr);
		}

# closing brace should have a space following it when it has anything
# on the line
		if ($line =~ /}(?!(?:,|;|\)))\S/) {
			ERROR("need a space after that close brace '}'\n" . $herecurr);
		}

# check spacing on square brackets
		if ($line =~ /\[\s/ && $line !~ /\[\s*$/) {
			ERROR("no space after that open square bracket '['\n" . $herecurr);
		}
		if ($line =~ /\s\]/) {
			ERROR("no space before that close square bracket ']'\n" . $herecurr);
		}

# check spacing on paretheses
		if ($line =~ /\(\s/ && $line !~ /\(\s*(?:\\)?$/ &&
		    $line !~ /for\s*\(\s+;/) {
			ERROR("no space after that open parenthesis '('\n" . $herecurr);
		}
		if ($line =~ /\s\)/ && $line !~ /^.\s*\)/ &&
		    $line !~ /for\s*\(.*;\s+\)/) {
			ERROR("no space before that close parenthesis ')'\n" . $herecurr);
		}

#goto labels aren't indented, allow a single space however
		if ($line=~/^.\s+[A-Za-z\d_]+:(?![0-9]+)/ and
		   !($line=~/^. [A-Za-z\d_]+:/) and !($line=~/^.\s+default:/)) {
			WARN("labels should not be indented\n" . $herecurr);
		}

# Need a space before open parenthesis after if, while etc
		if ($line=~/\b(if|while|for|switch)\(/) {
			ERROR("need a space before the open parenthesis '('\n" . $herecurr);
		}

# Check for illegal assignment in if conditional.
		if ($line =~ /\bif\s*\(/) {
			my ($s, $c) = ctx_statement_block($linenr, $realcnt, 0);

			if ($c =~ /\bif\s*\(.*[^<>!=]=[^=].*/) {
				ERROR("do not use assignment in if condition ($c)\n" . $herecurr);
			}

			# Find out what is on the end of the line after the
			# conditional.
			substr($s, 0, length($c)) = '';
			$s =~ s/\n.*//g;

			if (length($c) && $s !~ /^\s*({|;|\/\*.*\*\/)?\s*\\*\s*$/) {
				ERROR("trailing statements should be on next line\n" . $herecurr);
			}
		}

# if and else should not have general statements after it
		if ($line =~ /^.\s*(?:}\s*)?else\b(.*)/ &&
		    $1 !~ /^\s*(?:\sif|{|\\|$)/) {
			ERROR("trailing statements should be on next line\n" . $herecurr);
		}

		# Check for }<nl>else {, these must be at the same
		# indent level to be relevant to each other.
		if ($prevline=~/}\s*$/ and $line=~/^.\s*else\s*/ and
						$previndent == $indent) {
			ERROR("else should follow close brace '}'\n" . $hereprev);
		}

#studly caps, commented out until figure out how to distinguish between use of existing and adding new
#		if (($line=~/[\w_][a-z\d]+[A-Z]/) and !($line=~/print/)) {
#		    print "No studly caps, use _\n";
#		    print "$herecurr";
#		    $clean = 0;
#		}

#no spaces allowed after \ in define
		if ($line=~/\#define.*\\\s$/) {
			WARN("Whitepspace after \\ makes next lines useless\n" . $herecurr);
		}

#warn if <asm/foo.h> is #included and <linux/foo.h> is available (uses RAW line)
		if ($tree && $rawline =~ m{^.\#\s*include\s*\<asm\/(.*)\.h\>}) {
			my $checkfile = "$root/include/linux/$1.h";
			if (-f $checkfile && $1 ne 'irq.h') {
				CHK("Use #include <linux/$1.h> instead of <asm/$1.h>\n" .
					$herecurr);
			}
		}

# multi-statement macros should be enclosed in a do while loop, grab the
# first statement and ensure its the whole macro if its not enclosed
# in a known goot container
		if ($prevline =~ /\#define.*\\/ &&
		   $prevline !~/(?:do\s+{|\(\{|\{)/ &&
		   $line !~ /(?:do\s+{|\(\{|\{)/ &&
		   $line !~ /^.\s*$Declare\s/) {
			# Grab the first statement, if that is the entire macro
			# its ok.  This may start either on the #define line
			# or the one below.
			my $ln = $linenr;
			my $cnt = $realcnt;
			my $off = 0;

			# If the macro starts on the define line start
			# grabbing the statement after the identifier
			$prevline =~ m{^(.#\s*define\s*$Ident(?:\([^\)]*\))?\s*)(.*)\\\s*$};
			##print "1<$1> 2<$2>\n";
			if (defined $2 && $2 ne '') {
				$off = length($1);
				$ln--;
				$cnt++;
				while ($lines[$ln - 1] =~ /^-/) {
					$ln--;
					$cnt++;
				}
			}
			my @ctx = ctx_statement($ln, $cnt, $off);
			my $ctx_ln = $ln + $#ctx + 1;
			my $ctx = join("\n", @ctx);

			# Pull in any empty extension lines.
			while ($ctx =~ /\\$/ &&
			       $lines[$ctx_ln - 1] =~ /^.\s*(?:\\)?$/) {
				$ctx .= $lines[$ctx_ln - 1];
				$ctx_ln++;
			}

			if ($ctx =~ /\\$/) {
				if ($ctx =~ /;/) {
					ERROR("Macros with multiple statements should be enclosed in a do - while loop\n" . "$here\n$ctx\n");
				} else {
					ERROR("Macros with complex values should be enclosed in parenthesis\n" . "$here\n$ctx\n");
				}
			}
		}

# check for redundant bracing round if etc
		if ($line =~ /\b(if|while|for|else)\b/) {
			# Locate the end of the opening statement.
			my @control = ctx_statement($linenr, $realcnt, 0);
			my $nr = $linenr + (scalar(@control) - 1);
			my $cnt = $realcnt - (scalar(@control) - 1);

			my $off = $realcnt - $cnt;
			#print "$off: line<$line>end<" . $lines[$nr - 1] . ">\n";

			# If this is is a braced statement group check it
			if ($lines[$nr - 1] =~ /{\s*$/) {
				my ($lvl, @block) = ctx_block_level($nr, $cnt);

				my $stmt = join("\n", @block);
				# Drop the diff line leader.
				$stmt =~ s/\n./\n/g;
				# Drop the code outside the block.
				$stmt =~ s/(^[^{]*){\s*//;
				my $before = $1;
				$stmt =~ s/\s*}([^}]*$)//;
				my $after = $1;

				#print "block<" . join(' ', @block) . "><" . scalar(@block) . ">\n";
				#print "stmt<$stmt>\n\n";

				# Count the newlines, if there is only one
				# then the block should not have {}'s.
				my @lines = ($stmt =~ /\n/g);
				#print "lines<" . scalar(@lines) . ">\n";
				if ($lvl == 0 && scalar(@lines) == 0 &&
				    $stmt !~ /{/ && $stmt !~ /\bif\b/ &&
				    $before !~ /}/ && $after !~ /{/) {
				    	my $herectx = "$here\n" . join("\n", @control, @block[1 .. $#block]) . "\n";
				    	shift(@block);
					WARN("braces {} are not necessary for single statement blocks\n" . $herectx);
				}
			}
		}

# don't include deprecated include files (uses RAW line)
		for my $inc (@dep_includes) {
			if ($rawline =~ m@\#\s*include\s*\<$inc>@) {
				ERROR("Don't use <$inc>: see Documentation/feature-removal-schedule.txt\n" . $herecurr);
			}
		}

# don't use deprecated functions
		for my $func (@dep_functions) {
			if ($line =~ /\b$func\b/) {
				ERROR("Don't use $func(): see Documentation/feature-removal-schedule.txt\n" . $herecurr);
			}
		}

# no volatiles please
		my $asm_volatile = qr{\b(__asm__|asm)\s+(__volatile__|volatile)\b};
		if ($line =~ /\bvolatile\b/ && $line !~ /$asm_volatile/) {
			WARN("Use of volatile is usually wrong: see Documentation/volatile-considered-harmful.txt\n" . $herecurr);
		}

# SPIN_LOCK_UNLOCKED & RW_LOCK_UNLOCKED are deprecated
		if ($line =~ /\b(SPIN_LOCK_UNLOCKED|RW_LOCK_UNLOCKED)/) {
			ERROR("Use of $1 is deprecated: see Documentation/spinlocks.txt\n" . $herecurr);
		}

# warn about #if 0
		if ($line =~ /^.#\s*if\s+0\b/) {
			CHK("if this code is redundant consider removing it\n" .
				$herecurr);
		}

# check for needless kfree() checks
		if ($prevline =~ /\bif\s*\(([^\)]*)\)/) {
			my $expr = $1;
			if ($line =~ /\bkfree\(\Q$expr\E\);/) {
				WARN("kfree(NULL) is safe this check is probabally not required\n" . $hereprev);
			}
		}

# warn about #ifdefs in C files
#		if ($line =~ /^.#\s*if(|n)def/ && ($realfile =~ /\.c$/)) {
#			print "#ifdef in C files should be avoided\n";
#			print "$herecurr";
#			$clean = 0;
#		}

# warn about spacing in #ifdefs
		if ($line =~ /^.#\s*(ifdef|ifndef|elif)\s\s+/) {
			ERROR("exactly one space required after that #$1\n" . $herecurr);
		}

# check for spinlock_t definitions without a comment.
		if ($line =~ /^.\s*(struct\s+mutex|spinlock_t)\s+\S+;/) {
			my $which = $1;
			if (!ctx_has_comment($first_line, $linenr)) {
				CHK("$1 definition without comment\n" . $herecurr);
			}
		}
# check for memory barriers without a comment.
		if ($line =~ /\b(mb|rmb|wmb|read_barrier_depends|smp_mb|smp_rmb|smp_wmb|smp_read_barrier_depends)\(/) {
			if (!ctx_has_comment($first_line, $linenr)) {
				CHK("memory barrier without comment\n" . $herecurr);
			}
		}
# check of hardware specific defines
		if ($line =~ m@^.#\s*if.*\b(__i386__|__powerpc64__|__sun__|__s390x__)\b@ && $realfile !~ m@include/asm-@) {
			CHK("architecture specific defines should be avoided\n" .  $herecurr);
		}

# check the location of the inline attribute, that it is between
# storage class and type.
		if ($line =~ /\b$Type\s+$Inline\b/ ||
		    $line =~ /\b$Inline\s+$Storage\b/) {
			ERROR("inline keyword should sit between storage class and type\n" . $herecurr);
		}

# Check for __inline__ and __inline, prefer inline
		if ($line =~ /\b(__inline__|__inline)\b/) {
			WARN("plain inline is preferred over $1\n" . $herecurr);
		}

# check for new externs in .c files.
		if ($line =~ /^.\s*extern\s/ && ($realfile =~ /\.c$/)) {
			WARN("externs should be avoided in .c files\n" .  $herecurr);
		}

# checks for new __setup's
		if ($rawline =~ /\b__setup\("([^"]*)"/) {
			my $name = $1;

			if (!grep(/$name/, @setup_docs)) {
				CHK("__setup appears un-documented -- check Documentation/kernel-parameters.txt\n" . $herecurr);
			}
		}

# check for pointless casting of kmalloc return
		if ($line =~ /\*\s*\)\s*k[czm]alloc\b/) {
			WARN("unnecessary cast may hide bugs, see http://c-faq.com/malloc/mallocnocast.html\n" . $herecurr);
		}
	}

	# In mailback mode only produce a report in the negative, for
	# things that appear to be patches.
	if ($mailback && ($clean == 1 || !$is_patch)) {
		exit(0);
	}

	# This is not a patch, and we are are in 'no-patch' mode so
	# just keep quiet.
	if (!$chk_patch && !$is_patch) {
		exit(0);
	}

	if (!$is_patch) {
		ERROR("Does not appear to be a unified-diff format patch\n");
	}
	if ($is_patch && $chk_signoff && $signoff == 0) {
		ERROR("Missing Signed-off-by: line(s)\n");
	}

	print report_dump();
	if ($summary) {
		print "total: $cnt_error errors, $cnt_warn warnings, " .
			(($check)? "$cnt_chk checks, " : "") .
			"$cnt_lines lines checked\n";
		print "\n" if ($quiet == 0);
	}

	if ($clean == 1 && $quiet == 0) {
		print "Your patch has no obvious style problems and is ready for submission.\n"
	}
	if ($clean == 0 && $quiet == 0) {
		print "Your patch has style problems, please review.  If any of these errors\n";
		print "are false positives report them to the maintainer, see\n";
		print "CHECKPATCH in MAINTAINERS.\n";
	}
	return $clean;
}