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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=ham 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 5BD4BC43381 for ; Sun, 17 Feb 2019 11:37:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 220CD21B69 for ; Sun, 17 Feb 2019 11:37:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728352AbfBQLhV (ORCPT ); Sun, 17 Feb 2019 06:37:21 -0500 Received: from mail2-relais-roc.national.inria.fr ([192.134.164.83]:12380 "EHLO mail2-relais-roc.national.inria.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726168AbfBQLhU (ORCPT ); Sun, 17 Feb 2019 06:37:20 -0500 X-IronPort-AV: E=Sophos;i="5.58,380,1544482800"; d="scan'208";a="369731283" Received: from abo-58-107-68.mrs.modulonet.fr (HELO hadrien) ([85.68.107.58]) by mail2-relais-roc.national.inria.fr with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 17 Feb 2019 12:37:18 +0100 Date: Sun, 17 Feb 2019 12:37:18 +0100 (CET) From: Julia Lawall X-X-Sender: jll@hadrien To: Markus Elfring cc: Wen Yang , Gilles Muller , Nicolas Palix , Michal Marek , Masahiro Yamada , Wen Yang , Cheng Shengyu , kernel-janitors@vger.kernel.org, LKML , Coccinelle Subject: Re: [PATCH v6] coccinelle: semantic code search for missing put_device() In-Reply-To: <8e7ba7c0-b7fe-a1f0-d28b-0c716ecbcfdb@web.de> Message-ID: References: <8e7ba7c0-b7fe-a1f0-d28b-0c716ecbcfdb@web.de> User-Agent: Alpine 2.21 (DEB 202 2017-01-01) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, 17 Feb 2019, Markus Elfring wrote: > > +@search exists@ > > +local idexpression id; > > +expression x,e,e1; > > +position p1,p2; > > +type T,T1,T2; > > +@@ > > + > > +id = of_find_device_by_node@p1(x) > > +... when != e = id > > I suggest to increase your software development attention also for > another implementation detail. > Source code analysis triggers challenges for safe data flow handling. > the semantic patch language supports search specifications for > the exclusion of specific assignments. > > Does this SmPL code contain a questionable order for the source > and target metavariables? > Can the following variant be more appropriate? > > + ... when != id = e This is possible, but I think unlikely. > > > > +if (id == NULL || ...) { ... return ...; } > > +... when != put_device(&id->dev) > > + when != platform_device_put(id) > > + when != of_dev_put(id) > > + when != if (id) { ... put_device(&id->dev) ... } > > + when != e1 = (T)id > > Would you like to avoid that the return value from the shown function call > gets overwritten in the variable before it was used once at least > (when a bit of extra C code is tolerated before a null pointer check)? Indeed there should be a put then too, but again, it seems unlikely. julia > > Regards, > Markus >