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=-3.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 2488AC433FF for ; Fri, 2 Aug 2019 03:13:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id ED558206A3 for ; Fri, 2 Aug 2019 03:13:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728170AbfHBDNK (ORCPT ); Thu, 1 Aug 2019 23:13:10 -0400 Received: from smtprelay0078.hostedemail.com ([216.40.44.78]:47735 "EHLO smtprelay.hostedemail.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726014AbfHBDNK (ORCPT ); Thu, 1 Aug 2019 23:13:10 -0400 Received: from filter.hostedemail.com (clb03-v110.bra.tucows.net [216.40.38.60]) by smtprelay05.hostedemail.com (Postfix) with ESMTP id B6B4B180295BD; Fri, 2 Aug 2019 03:13:08 +0000 (UTC) X-Session-Marker: 6A6F6540706572636865732E636F6D X-HE-Tag: bone24_5581e2d354449 X-Filterd-Recvd-Size: 2113 Received: from XPS-9350 (cpe-23-242-196-136.socal.res.rr.com [23.242.196.136]) (Authenticated sender: joe@perches.com) by omf16.hostedemail.com (Postfix) with ESMTPA; Fri, 2 Aug 2019 03:13:07 +0000 (UTC) Message-ID: Subject: Re: [PATCH v2 06/10] printk: Replace strncmp with str_has_prefix From: Joe Perches To: Chuhong Yuan Cc: Petr Mladek , Sergey Senozhatsky , Steven Rostedt , linux-kernel@vger.kernel.org Date: Thu, 01 Aug 2019 20:13:06 -0700 In-Reply-To: <20190802014718.8952-1-hslester96@gmail.com> References: <20190802014718.8952-1-hslester96@gmail.com> Content-Type: text/plain; charset="ISO-8859-1" User-Agent: Evolution 3.30.5-0ubuntu0.18.10.1 MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 2019-08-02 at 09:47 +0800, Chuhong Yuan wrote: > strncmp(str, const, len) is error-prone because len > is easy to have typo. > The example is the hard-coded len has counting error > or sizeof(const) forgets - 1. > So we prefer using newly introduced str_has_prefix > to substitute such strncmp. [] > diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c [] > @@ -118,18 +118,20 @@ static unsigned int __read_mostly devkmsg_log = DEVKMSG_LOG_MASK_DEFAULT; > > static int __control_devkmsg(char *str) > { > + size_t len; > + > if (!str) > return -EINVAL; > > - if (!strncmp(str, "on", 2)) { > + if ((len = str_has_prefix(str, "on"))) { > devkmsg_log = DEVKMSG_LOG_MASK_ON; > - return 2; > - } else if (!strncmp(str, "off", 3)) { > + return len; > + } else if ((len = str_has_prefix(str, "off"))) { > devkmsg_log = DEVKMSG_LOG_MASK_OFF; > - return 3; > - } else if (!strncmp(str, "ratelimit", 9)) { > + return len; > + } else if ((len = str_has_prefix(str, "ratelimit"))) { > devkmsg_log = DEVKMSG_LOG_MASK_DEFAULT; > - return 9; > + return len; > } > return -EINVAL; > } All of the else uses above could also be removed.