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,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 309ECC4321A for ; Sat, 29 Jun 2019 07:49:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E5C2E214DA for ; Sat, 29 Jun 2019 07:49:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726879AbfF2HtG (ORCPT ); Sat, 29 Jun 2019 03:49:06 -0400 Received: from mail3-relais-sop.national.inria.fr ([192.134.164.104]:42778 "EHLO mail3-relais-sop.national.inria.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726796AbfF2HtG (ORCPT ); Sat, 29 Jun 2019 03:49:06 -0400 X-IronPort-AV: E=Sophos;i="5.63,430,1557180000"; d="scan'208";a="311853501" Received: from abo-12-105-68.mrs.modulonet.fr (HELO hadrien) ([85.68.105.12]) by mail3-relais-sop.national.inria.fr with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 29 Jun 2019 09:49:04 +0200 Date: Sat, 29 Jun 2019 09:49:04 +0200 (CEST) From: Julia Lawall X-X-Sender: jll@hadrien To: Markus Elfring cc: Wen Yang , linux-kernel@vger.kernel.org, cocci@systeme.lip6.fr, Yi Wang , Gilles Muller , Nicolas Palix , Michal Marek , Masahiro Yamada Subject: Re: [v2] coccinelle: semantic code search for missing of_node_put In-Reply-To: <76641efc-2e3e-8664-03b2-4eb82f01c275@web.de> Message-ID: References: <1561690732-20694-1-git-send-email-wen.yang99@zte.com.cn> <904b9362-cd01-ffc9-600b-0c48848617a0@web.de> <76641efc-2e3e-8664-03b2-4eb82f01c275@web.de> User-Agent: Alpine 2.21 (DEB 202 2017-01-01) MIME-Version: 1.0 Content-Type: multipart/mixed; boundary="8323329-766857525-1561794544=:2579" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This message is in MIME format. The first part should be readable text, while the remaining parts are likely unreadable without MIME-aware tools. --8323329-766857525-1561794544=:2579 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8BIT On Sat, 29 Jun 2019, Markus Elfring wrote: > >> +if (x == NULL || ...) S > >> +... when != e = (T)x > >> + when != true x == NULL > > > > I wonder if this code exclusion specification is really required > > after a null pointer was checked before. > > I would like to add another view for this implementation detail. > > The when constraint can express a software desire which can be reasonable > to some degree. You would like to be sure that a null pointer will not occur > after a corresponding check succeeded. He wants to be sure that the true branch through a NULL pointer check is not taken. > * But I feel unsure about the circumstances under which the Coccinelle software > can determine this aspect actually. > > * I find that it can eventually make sense only after the content of > the local variable (which is identified by “x”) was modified. > Thus I would find the exclusion of assignments more useful at this place. I assume that it was added because it was found to be useful. Please actually try things out before declaring them to be useless. julia --8323329-766857525-1561794544=:2579--