From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753618AbbH0Rd3 (ORCPT ); Thu, 27 Aug 2015 13:33:29 -0400 Received: from smtprelay0193.hostedemail.com ([216.40.44.193]:50192 "EHLO smtprelay.hostedemail.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752497AbbH0Rd1 (ORCPT ); Thu, 27 Aug 2015 13:33:27 -0400 X-Session-Marker: 6A6F6540706572636865732E636F6D X-Spam-Summary: 2,0,0,,d41d8cd98f00b204,joe@perches.com,:::::::::,RULES_HIT:41:355:379:541:800:960:973:982:988:989:1260:1277:1311:1313:1314:1345:1359:1373:1437:1515:1516:1518:1534:1542:1593:1594:1711:1730:1747:1777:1792:2197:2199:2393:2559:2562:2828:3138:3139:3140:3141:3142:3353:3653:3865:3866:3867:3868:3871:3872:4605:5007:6261:7903:8957:9121:10004:10400:10848:11658:11914:12043:12291:12517:12519:12555:14394:21063:21080:21221,0,RBL:none,CacheIP:none,Bayesian:0.5,0.5,0.5,Netcheck:none,DomainCache:0,MSF:not bulk,SPF:fn,MSBL:0,DNSBL:none,Custom_rules:0:0:0 X-HE-Tag: copy33_74fd6c3188160 X-Filterd-Recvd-Size: 3241 Message-ID: <1440696802.11525.96.camel@perches.com> Subject: [PATCH] checkpatch: add constant comparison on left side test From: Joe Perches To: Andrew Morton Cc: Nicolas Morey Chaisemartin , Viresh Kumar , Dan Carpenter , LKML Date: Thu, 27 Aug 2015 10:33:22 -0700 In-Reply-To: <1440660159.11525.79.camel@perches.com> References: <1415905054.4223.7.camel@perches.com> <1440644737.11525.64.camel@perches.com> <975828790.5069815.1440659347329.JavaMail.zimbra@kalray.eu> <1440660159.11525.79.camel@perches.com> Content-Type: text/plain; charset="ISO-8859-1" X-Mailer: Evolution 3.12.11-0ubuntu3 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org "CONST variable" checks like: if (NULL != foo) and while (0 < bar(...)) where a constant (or what appears to be a constant like an upper case identifier) is on the left of a comparison are generally preferred to be written using the constant on the right side like: if (foo != NULL) and while (bar(...) > 0) Add a test for this. Add a --fix option too, but only do it when the code is immediately surrounded by parentheses to avoid misfixing things like "(0 < bar() + constant)" Signed-off-by: Joe Perches --- scripts/checkpatch.pl | 29 +++++++++++++++++++++++++++++ 1 file changed, 29 insertions(+) diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl index e14dcdb..5fca1da 100755 --- a/scripts/checkpatch.pl +++ b/scripts/checkpatch.pl @@ -4231,6 +4231,35 @@ sub process { } } +# comparisons with a constant or upper case identifier on the left +# avoid cases like "foo + BAR < baz" +# only fix matches surrounded by parentheses to avoid incorrect +# conversions like "FOO < baz() + 5" being "misfixed" to "baz() > FOO + 5" + if ($^V && $^V ge 5.10.0 && + $line =~ /^\+(.*)\b($Constant|[A-Z_][A-Z0-9_]*)\s*($Compare)\s*($LvalOrFunc)/) { + my $lead = $1; + my $const = $2; + my $comp = $3; + my $to = $4; + my $newcomp = $comp; + if ($lead !~ /$Operators\s*$/ && + $to !~ /^(?:Constant|[A-Z_][A-Z0-9_]*)$/ && + WARN("CONSTANT_COMPARISON", + "Comparisons should place the constant on the right side of the test\n" . $herecurr) && + $fix) { + if ($comp eq "<") { + $newcomp = ">"; + } elsif ($comp eq "<=") { + $newcomp = ">="; + } elsif ($comp eq ">") { + $newcomp = "<"; + } elsif ($comp eq ">=") { + $newcomp = "<="; + } + $fixed[$fixlinenr] =~ s/\(\s*\Q$const\E\s*$Compare\s*\Q$to\E\s*\)/($to $newcomp $const)/; + } + } + # Return of what appears to be an errno should normally be negative if ($sline =~ /\breturn(?:\s*\(+\s*|\s+)(E[A-Z]+)(?:\s*\)+\s*|\s*)[;:,]/) { my $name = $1;