From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id ABC31C433DF for ; Thu, 4 Jun 2020 15:51:51 +0000 (UTC) Received: from isis.lip6.fr (isis.lip6.fr [132.227.60.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 38F0A20738 for ; Thu, 4 Jun 2020 15:51:51 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 38F0A20738 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=inria.fr Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=cocci-bounces@systeme.lip6.fr Received: from systeme.lip6.fr (systeme.lip6.fr [132.227.104.7]) by isis.lip6.fr (8.15.2/8.15.2) with ESMTP id 054FpmeP024005; Thu, 4 Jun 2020 17:51:48 +0200 (CEST) Received: from systeme.lip6.fr (systeme.lip6.fr [127.0.0.1]) by systeme.lip6.fr (Postfix) with ESMTP id 6141E7567; Thu, 4 Jun 2020 17:51:48 +0200 (CEST) Received: from isis.lip6.fr (isis.lip6.fr [132.227.60.2]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by systeme.lip6.fr (Postfix) with ESMTPS id BBAB85D47 for ; Thu, 4 Jun 2020 17:51:46 +0200 (CEST) Received: from mail3-relais-sop.national.inria.fr (mail3-relais-sop.national.inria.fr [192.134.164.104]) by isis.lip6.fr (8.15.2/8.15.2) with ESMTPS id 054FpimR004377 (version=TLSv1.2 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK) for ; Thu, 4 Jun 2020 17:51:44 +0200 (CEST) X-IronPort-AV: E=Sophos;i="5.73,472,1583190000"; d="scan'208";a="350605555" Received: from abo-173-121-68.mrs.modulonet.fr (HELO hadrien) ([85.68.121.173]) by mail3-relais-sop.national.inria.fr with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 04 Jun 2020 17:51:20 +0200 Date: Thu, 4 Jun 2020 17:51:19 +0200 (CEST) From: Julia Lawall X-X-Sender: jll@hadrien To: Denis Efremov In-Reply-To: Message-ID: References: <20200604140805.111613-1-efremov@linux.com> User-Agent: Alpine 2.21 (DEB 202 2017-01-01) MIME-Version: 1.0 X-Greylist: Sender IP whitelisted, Sender e-mail whitelisted, not delayed by milter-greylist-4.4.3 (isis.lip6.fr [132.227.60.2]); Thu, 04 Jun 2020 17:51:48 +0200 (CEST) X-Greylist: Sender passed SPF test, not delayed by milter-greylist-4.4.3 (isis.lip6.fr [132.227.60.2]); Thu, 04 Jun 2020 17:51:44 +0200 (CEST) X-Scanned-By: MIMEDefang 2.78 on 132.227.60.2 X-Scanned-By: MIMEDefang 2.78 on 132.227.60.2 Cc: cocci@systeme.lip6.fr, linux-kernel@vger.kernel.org Subject: Re: [Cocci] [PATCH] coccinelle: api: add kzfree script X-BeenThere: cocci@systeme.lip6.fr X-Mailman-Version: 2.1.13 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: cocci-bounces@systeme.lip6.fr Errors-To: cocci-bounces@systeme.lip6.fr On Thu, 4 Jun 2020, Denis Efremov wrote: > > > On 6/4/20 5:15 PM, Julia Lawall wrote: > > Did you try ... here but find that some subexpressions of E could be > > modified in between? > > Yes, I tried to use "... when != E = E1 when != &E" and results were bad. > Now, I've tried forall and when strict. Here are examples: > > // forall added > // Works well, suitable for v2. One additional catch in w1 driver. > @r depends on !patch && !(file in "lib/test_kasan.c") && !(file in "mm/slab_common.c") forall@ > expression *E; // pointer. Results are equal as if we use E. > position p; > @@ > > * memset(E, 0, ...); > ... when != E // Is it enough to match &E, E = E1? Yes. > * kfree(E)@p; > > //no forall, when strict > //results are bad, too many false positives > @r depends on !patch && !(file in "lib/test_kasan.c") && !(file in "mm/slab_common.c")@ > expression *E; > position p; > @@ > > * memset(E, 0, ...); > ... when != E // E is not enough here > when strict OK, it's reassonable. > * kfree(E)@p; > > I guess that the difference is that "forall" requires that whole pattern should occur on > every path, "when strict" states that kfree should be called on every path after memset. > This results in missed uses of E in loops and under conditions. How can I state in this > case that E should not occur at all (in all paths) in between memset, kfree even as a > subexpression? > > // Doesn't work well > ... when != E > when != if (...) { ... E ... } > when != for(...;...;...) { ... E ... } Could you send an example of some C code on which the result is not suitable? julia _______________________________________________ Cocci mailing list Cocci@systeme.lip6.fr https://systeme.lip6.fr/mailman/listinfo/cocci