From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754798AbbL3Mdk (ORCPT ); Wed, 30 Dec 2015 07:33:40 -0500 Received: from mailout3.w1.samsung.com ([210.118.77.13]:57753 "EHLO mailout3.w1.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754699AbbL3Mdj (ORCPT ); Wed, 30 Dec 2015 07:33:39 -0500 X-AuditID: cbfec7f5-f79b16d000005389-85-5683cf2086ea Subject: Re: [PATCH v4] coccinelle: tests: unsigned value cannot be lesser than zero To: Julia Lawall References: <1451473583-15333-1-git-send-email-a.hajda@samsung.com> Cc: Bartlomiej Zolnierkiewicz , Marek Szyprowski , Gilles Muller , Nicolas Palix , Michal Marek , open list , "moderated list:COCCINELLE/Semantic Patches (SmPL)" Newsgroups: gmane.linux.kernel,gmane.comp.version-control.coccinelle From: Andrzej Hajda Message-id: <5683CF1A.1030109@samsung.com> Date: Wed, 30 Dec 2015 13:33:30 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.4.0 MIME-version: 1.0 In-reply-to: Content-type: text/plain; charset=windows-1252 Content-transfer-encoding: 7bit X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFnrHLMWRmVeSWpSXmKPExsVy+t/xa7oK55vDDA6eYrfYOGM9q8WPTavZ LGb/vMRksezBaUaLy7vmsFmsPXKX3WJO6yw2i2MvlzM5cHgcO9bK7LF3S5ZH35ZVjB7rt1xl 8Xi07D6Lx+dNcgFsUVw2Kak5mWWpRfp2CVwZj85tYSvYyVfx6usytgbGRdxdjJwcEgImEvfu PGCDsMUkLtxbD2RzcQgJLGWUePZ0DpTznFFi+dyXTCBVwgJhEo8vfGbpYuTgEBFQl+j9kAsS FhJoYpToPCMLUs8scIlJYsWvlywgCT4BF4mujh2MIDabgKbE3803wbbxCmhJdC3sBrNZBFQl lp+ZygoyU1QgQmLRjkyIEkGJH5PvgY3hFPCUmLPmIjNICbOAnsT9i1ogYWYBeYnNa94yT2AU nIWkYxZC1SwkVQsYmVcxiqaWJhcUJ6XnGukVJ+YWl+al6yXn525ihMTC1x2MS49ZHWIU4GBU 4uE9IdQcJsSaWFZcmXuIUYKDWUmEd8EmoBBvSmJlVWpRfnxRaU5q8SFGaQ4WJXHembvehwgJ pCeWpGanphakFsFkmTg4pRoYV8w68vrVDbP/zv6BTo/PM03zS+M9xtQjH1+XH3qZ6/N2sQNJ c9ov/si7OmdqdHmQ6J/nRnkZf/r1t/3TCQr7l5mmycN6zSRhgeUGIeUPyzQ4/Zbab98akD/X ubDfV/PIJ5a1EqzTpix4ahJ4R19+th1rCXeCWWTsr1sa9zOtfn9wCpWa2MKjxFKckWioxVxU nAgA7pKjHoECAAA= Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/30/2015 12:29 PM, Julia Lawall wrote: > > > On Wed, 30 Dec 2015, Andrzej Hajda wrote: > >> Unsigned expressions cannot be lesser than zero. Presence of comparisons >> 'unsigned (<|<=|>|>=) 0' often indicates a bug, usually wrong type of variable. >> The patch beside finding such comparisons tries to eliminate false positives, >> mainly by bypassing range checks. >> >> gcc can detect such comparisons also using -Wtype-limits switch, but it warns >> also in correct cases, making too much noise. >> >> Signed-off-by: Andrzej Hajda >> --- >> v4: added range check detection, added full check in case value holds a result >> of signed function >> v3: added bool type >> v2: added --all-includes option >> --- >> Hi Julia, >> >> This version adds range check detection, as a result false positives are almost >> fully eliminated. Most of kernel patches have been already sent and accepted, >> but some new bugs appeared since then. I will prepare bugfixes soon. >> >> I have enountered one issue, the patch does not detect range check in >> drivers/leds/leds-tca6507.c:716: >> if (ret != 0 || reg < 0 || reg >= NUM_LEDS) >> >> Simplified check, responsible for detectin range checks: >> @@ >> expression v, c; >> @@ >> >> * (\( v < 0 \| v <= 0 \)) || (\( v >= c \| v > c \)) >> >> Is it a bug or expected behavior? Maybe consequence of left-to-right associativity? > > Yes, it would be an associativity problem. Could you try with || ... > added to the right end of your pattern? That should allow it to let the > disjunctions appear anywhere at top level, but I'm not sure to what extent > it works when the pattern already contains a disjunction. You could also > try > > A || ... || B || ... > "A || ... || B" does the trick. Regards Andrzej