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=-9.3 required=3.0 tests=DKIM_ADSP_CUSTOM_MED, DKIM_INVALID,DKIM_SIGNED,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT 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 D259AC31E40 for ; Fri, 9 Aug 2019 07:10:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A77AC208C4 for ; Fri, 9 Aug 2019 07:10:41 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="mDpqdxWD" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2405768AbfHIHKk (ORCPT ); Fri, 9 Aug 2019 03:10:40 -0400 Received: from mail-pg1-f193.google.com ([209.85.215.193]:34008 "EHLO mail-pg1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2405700AbfHIHKk (ORCPT ); Fri, 9 Aug 2019 03:10:40 -0400 Received: by mail-pg1-f193.google.com with SMTP id n9so39176644pgc.1 for ; Fri, 09 Aug 2019 00:10:39 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=a5eAdforJPfI5AutgpY5E1bO5+BesI2S6rA/D6o6CCg=; b=mDpqdxWDR7UvCn1miherHFNhhyu2Kkby2aYHMvu/Z6T2H4gQWGSJfK6hIWYjRSBfQn KDyu0PLfk59UXPoaYBJ2xI1gqYX5k5UgZMgxshPGV3THmYfGTH3rf+vKRKdSHXSMJv77 4m/zBzvWu8+I0NqnXCGSL8xi6xIAShYizPpHugV6SoyAUtLntF0C75dw4YuDkmt7xYIT n072RcSqR9vMBpZzWyHWMBdv9Rko+v2uuUpJfyYx18I1xhtFPti0gIxyOMyn+PFUSgey Px+OGtHKtB0JH8RK/9AFfJlhCBeiD6Ba3S58ZpD7IrD+LSZTwEtBCUrNV68BCW7rMr9d CZeQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=a5eAdforJPfI5AutgpY5E1bO5+BesI2S6rA/D6o6CCg=; b=ZhsYHU0nTTPTjsLF4tRHJQ0ZBYdntsbOYWVUHlR5TJx3O9AFjrNdxYHmtSHG6GkV/J 37psQliZWsjOgrpRPxwX7fHiGmxIT65G4QTPUyMjSX1Jt3udnYa5dEcTkQuHmiKLVRbC zpSb7tDSuz5djDR4WS/z0pPU0I10vxmqsMs6Yn6DU67OWdNP4g6GDxTCdNS93TCryNra 2dm1tHQeJpuMhUHN1YynnjvrUqjwln4rsH/ijbBx2Q9G1xJfvcKfgaW4wNtiD0cOKMvZ 8hJ1b3CClzOqm11D4oITVTLNSmNB8WipukNvXmxSHqbjrjGJHjpSCyASHykr2KWR3baK EHZw== X-Gm-Message-State: APjAAAVPDiuaRJFeFjxZnPOmOWi4qkp440TZbzD+lCafviwxvpVvSriu kVokXVOOzLKMhVkgNTrOckc= X-Google-Smtp-Source: APXvYqxuZQXlgouixG8Pwov2oZwIMRepy53nKGcS1bzzPx5sYz+Mga8r1S/1irrQAxELbQPd1OBJHw== X-Received: by 2002:a65:43c2:: with SMTP id n2mr16339061pgp.110.1565334639457; Fri, 09 Aug 2019 00:10:39 -0700 (PDT) Received: from suzukaze.ipads-lab.se.sjtu.edu.cn ([89.31.126.54]) by smtp.gmail.com with ESMTPSA id k25sm82073711pgt.53.2019.08.09.00.10.37 (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Fri, 09 Aug 2019 00:10:38 -0700 (PDT) From: Chuhong Yuan Cc: Petr Mladek , Sergey Senozhatsky , Steven Rostedt , linux-kernel@vger.kernel.org, Chuhong Yuan Subject: [PATCH v4 4/8] printk: Replace strncmp with str_has_prefix Date: Fri, 9 Aug 2019 15:10:34 +0800 Message-Id: <20190809071034.17279-1-hslester96@gmail.com> X-Mailer: git-send-email 2.20.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit To: unlisted-recipients:; (no To-header on input) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 to make code better. Signed-off-by: Chuhong Yuan --- Changes in v4: - Eliminate assignments in if conditions. kernel/printk/braille.c | 15 +++++++++++---- kernel/printk/printk.c | 22 ++++++++++++++++------ 2 files changed, 27 insertions(+), 10 deletions(-) diff --git a/kernel/printk/braille.c b/kernel/printk/braille.c index 1d21ebacfdb8..17a9591e54ff 100644 --- a/kernel/printk/braille.c +++ b/kernel/printk/braille.c @@ -11,11 +11,18 @@ int _braille_console_setup(char **str, char **brl_options) { - if (!strncmp(*str, "brl,", 4)) { + size_t len; + + len = str_has_prefix(*str, "brl,"); + if (len) { *brl_options = ""; - *str += 4; - } else if (!strncmp(*str, "brl=", 4)) { - *brl_options = *str + 4; + *str += len; + return 0; + } + + len = str_has_prefix(*str, "brl="); + if (len) { + *brl_options = *str + len; *str = strchr(*brl_options, ','); if (!*str) { pr_err("need port name after brl=\n"); diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c index 1888f6a3b694..43a31015ec93 100644 --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -118,19 +118,29 @@ 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)) { + len = str_has_prefix(str, "on"); + if (len) { devkmsg_log = DEVKMSG_LOG_MASK_ON; - return 2; - } else if (!strncmp(str, "off", 3)) { + return len; + } + + len = str_has_prefix(str, "off"); + if (len) { devkmsg_log = DEVKMSG_LOG_MASK_OFF; - return 3; - } else if (!strncmp(str, "ratelimit", 9)) { + return len; + } + + len = str_has_prefix(str, "ratelimit"); + if (len) { devkmsg_log = DEVKMSG_LOG_MASK_DEFAULT; - return 9; + return len; } + return -EINVAL; } -- 2.20.1