Commit 7d2367af authored by Joe Perches's avatar Joe Perches Committed by Linus Torvalds
Browse files

checkpatch: suggest using min_t or max_t 



A common issue with min() or max() is using a cast on one or both of the
arguments when using min_t/max_t could be better.

Add cast detection to uses of min/max and suggest an appropriate use of
min_t or max_t instead.

Caveat:  This only works for min() or max() on a single line.
         It does not find min() or max() split across multiple lines.

This does find:
	min((u32)foo, bar);
But it does not find:
	max((unsigned long)foo,
	    bar);

Suggested-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarJoe Perches <joe@perches.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 27c46a25

scripts/checkpatch.pl

+35 −0
Original line number Diff line number Diff line
@@ -268,6 +268,20 @@ sub build_types { 
}

build_types();



our $match_balanced_parentheses = qr/(\((?:[^\(\)]+|(-1))*\))/;



our $Typecast	= qr{\s*(\(\s*$NonptrType\s*\)){0,1}\s*};

our $LvalOrFunc	= qr{($Lval)\s*($match_balanced_parentheses{0,1})\s*};



sub deparenthesize {

	my ($string) = @_;

	return "" if (!defined($string));

	$string =~ s@^\s*\(\s*@@g;

	$string =~ s@\s*\)\s*$@@g;

	$string =~ s@\s+@ @g;

	return $string;

}



$chk_signoff = 0 if ($file);



my @dep_includes = ();
@@ -2290,6 +2304,27 @@ sub process { 
			}

		}



# typecasts on min/max could be min_t/max_t

		if ($line =~ /^\+(?:.*?)\b(min|max)\s*\($Typecast{0,1}($LvalOrFunc)\s*,\s*$Typecast{0,1}($LvalOrFunc)\s*\)/) {

			if (defined $2 || defined $8) {

				my $call = $1;

				my $cast1 = deparenthesize($2);

				my $arg1 = $3;

				my $cast2 = deparenthesize($8);

				my $arg2 = $9;

				my $cast;



				if ($cast1 ne "" && $cast2 ne "") {

					$cast = "$cast1 or $cast2";

				} elsif ($cast1 ne "") {

					$cast = $cast1;

				} else {

					$cast = $cast2;

				}

				WARN("$call() should probably be ${call}_t($cast, $arg1, $arg2)\n" . $herecurr);

			}

		}



# Need a space before open parenthesis after if, while etc

		if ($line=~/\b(if|while|for|switch)\(/) {

			ERROR("space required before the open parenthesis '('\n" . $herecurr);

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