From patchwork Fri Oct 16 02:49:00 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrew Morton X-Patchwork-Id: 11840759 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 06DA514B4 for ; Fri, 16 Oct 2020 02:49:05 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id B0288208C7 for ; Fri, 16 Oct 2020 02:49:04 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="kiXG9M5N" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B0288208C7 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 9C5EF940065; Thu, 15 Oct 2020 22:49:03 -0400 (EDT) Delivered-To: linux-mm-outgoing@kvack.org Received: by kanga.kvack.org (Postfix, from userid 40) id 94EE4940034; Thu, 15 Oct 2020 22:49:03 -0400 (EDT) X-Original-To: int-list-linux-mm@kvack.org X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 83E83940065; Thu, 15 Oct 2020 22:49:03 -0400 (EDT) X-Original-To: linux-mm@kvack.org X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0043.hostedemail.com [216.40.44.43]) by kanga.kvack.org (Postfix) with ESMTP id 5455A940034 for ; Thu, 15 Oct 2020 22:49:03 -0400 (EDT) Received: from smtpin22.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id F02F7181AEF00 for ; Fri, 16 Oct 2020 02:49:02 +0000 (UTC) X-FDA: 77376256524.22.place98_1714af527219 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin22.hostedemail.com (Postfix) with ESMTP id C7C8A18038E60 for ; Fri, 16 Oct 2020 02:49:02 +0000 (UTC) X-Spam-Summary: 1,0,0,5da028a3712f68d8,d41d8cd98f00b204,akpm@linux-foundation.org,,RULES_HIT:41:355:379:800:960:967:968:973:982:988:989:1260:1345:1359:1381:1431:1437:1534:1541:1711:1730:1747:1777:1792:2197:2199:2393:2525:2559:2563:2682:2685:2859:2902:2933:2937:2939:2942:2945:2947:2951:2954:3022:3138:3139:3140:3141:3142:3352:3653:3865:3867:3868:3872:3874:3934:3936:3938:3941:3944:3947:3950:3953:3956:3959:5007:6261:6653:7576:9025:9545:10004:11658:11914:12043:12048:12296:12297:12438:12517:12519:12555:12679:13069:13161:13229:13311:13357:13846:14093:14181:14384:14721:21080:21221:21451:21627:21939:30054:30070,0,RBL:198.145.29.99:@linux-foundation.org:.lbl8.mailshell.net-62.2.0.100 64.100.201.201;04y8jgzjq5n4cy65u7b5tmchs538tycjoit616zr63r3utfcrgbqym9mwczxpxd.d9hhjwyw1n6k8e9p76kwuckcgz5pxrkyz7n6jbaohbcwxbfqrte1rpgrpsfojbp.n-lbl8.mailshell.net-223.238.255.100,CacheIP:none,Bayesian:0.5,0.5,0.5,Netcheck:none,DomainCache:0,MSF:not bulk,SPF:fp,MSBL:0,DNSBL:neutral,Custom_rules:0:0:0,LFtim e:23,LUA X-HE-Tag: place98_1714af527219 X-Filterd-Recvd-Size: 3202 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf37.hostedemail.com (Postfix) with ESMTP for ; Fri, 16 Oct 2020 02:49:02 +0000 (UTC) Received: from localhost.localdomain (c-73-231-172-41.hsd1.ca.comcast.net [73.231.172.41]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 022352087D; Fri, 16 Oct 2020 02:49:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1602816541; bh=+zm8JEJDvdWTDvYHkQ5bHIwYYLcmpSp2CxNSfmGjWws=; h=Date:From:To:Subject:In-Reply-To:From; b=kiXG9M5NrbbXRXdX9LveyBaWtLGecVydxaunLwI3St1a4IdpqVOl/VA5CK5p09S1N emLqiax+hZWviK1o3ZfnMW00nd0iNIn66GnkACH4TlddqdVVsHImhSp0lZX8kBEx5M cLCNTzOkS0GVkIJ5K9nwCUQ1pJ1CKV3vk4WXoHPA= Date: Thu, 15 Oct 2020 19:49:00 -0700 From: Andrew Morton To: akpm@linux-foundation.org, efremov@linux.com, gustavoars@kernel.org, joe@perches.com, julia.lawall@inria.fr, keescook@chromium.org, linux-mm@kvack.org, mm-commits@vger.kernel.org, torvalds@linux-foundation.org Subject: [patch 127/156] checkpatch: warn on self-assignments Message-ID: <20201016024900.rKnqH0xK7%akpm@linux-foundation.org> In-Reply-To: <20201015192732.f448da14e9854c7cb7299956@linux-foundation.org> User-Agent: s-nail v14.8.16 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: From: Joe Perches Subject: checkpatch: warn on self-assignments The uninitialized_var() macro was removed recently via commit 63a0895d960a ("compiler: Remove uninitialized_var() macro") as it's not a particularly useful warning and its use can "paper over real bugs". Add a checkpatch test to warn on self-assignments as a means to avoid compiler warnings and as a back-door mechanism to reproduce the old uninitialized_var macro behavior. [akpm@linux-foundation.org: coding style fixes] Link: https://lkml.kernel.org/r/afc2cffdd315d3e4394af149278df9e8af7f49f4.camel@perches.com Signed-off-by: Joe Perches Cc: Kees Cook Cc: Gustavo A. R. Silva Cc: Denis Efremov Cc: Julia Lawall Signed-off-by: Andrew Morton --- scripts/checkpatch.pl | 11 +++++++++++ 1 file changed, 11 insertions(+) --- a/scripts/checkpatch.pl~checkpatch-warn-on-self-assignments +++ a/scripts/checkpatch.pl @@ -3899,6 +3899,17 @@ sub process { #ignore lines not being added next if ($line =~ /^[^\+]/); +# check for self assignments used to avoid compiler warnings +# e.g.: int foo = foo, *bar = NULL; +# struct foo bar = *(&(bar)); + if ($line =~ /^\+\s*(?:$Declare)?([A-Za-z_][A-Za-z\d_]*)\s*=/) { + my $var = $1; + if ($line =~ /^\+\s*(?:$Declare)?$var\s*=\s*(?:$var|\*\s*\(?\s*&\s*\(?\s*$var\s*\)?\s*\)?)\s*[;,]/) { + WARN("SELF_ASSIGNMENT", + "Do not use self-assignments to avoid compiler warnings\n" . $herecurr); + } + } + # check for dereferences that span multiple lines if ($prevline =~ /^\+.*$Lval\s*(?:\.|->)\s*$/ && $line =~ /^\+\s*(?!\#\s*(?!define\s+|if))\s*$Lval/) {