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checkpatch: suggest using min_t or max_t

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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: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Joe Perches 2011-07-25 17:13:22 -07:00 committed by Linus Torvalds
parent 27c46a2546
commit 7d2367af0b
1 changed files with 35 additions and 0 deletions
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35
scripts/checkpatch.pl
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@ -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);