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 533EBC433FF for ; Fri, 9 Aug 2019 07:10:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 27A19208C4 for ; Fri, 9 Aug 2019 07:10:59 +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="ExW1GuZ7" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2405791AbfHIHK5 (ORCPT ); Fri, 9 Aug 2019 03:10:57 -0400 Received: from mail-pg1-f196.google.com ([209.85.215.196]:36184 "EHLO mail-pg1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2405637AbfHIHK5 (ORCPT ); Fri, 9 Aug 2019 03:10:57 -0400 Received: by mail-pg1-f196.google.com with SMTP id l21so45391695pgm.3 for ; Fri, 09 Aug 2019 00:10:56 -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=HmVTzMroi4wKPHeymf1bmR1J99J9U+VX7aA5kNGTesM=; b=ExW1GuZ7EVry7wLfjaaBcxIuJkZtbypTeIQO5+tsrYw2aoD1hkftD+zza89I8E6a0f pwKHck5/S6YgLE/PXazozkfggA339pOqhQKDES/tmWhrEDiXOsfLZhXk9KKQyRUJ87Vd d+UWYeqeT0VRMYZWwDl6cTzRJB1n4JULsLiBv6LzF8+BZ2DKe9t78cIwzzqYb2wHvIj7 zc+KK/P4FZD63zDFH6lI4TuzrE5FKz3YY8DUmDxi1LrH4F7XuC2gqKF3y+2FpU17g7jp HeA8ClQmCxUXoZu6Ig0QRbFa3YUATrqQY6nxdI2N1P8i1hkN20iRh54BTZj+AZyy6lOa xyPw== 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=HmVTzMroi4wKPHeymf1bmR1J99J9U+VX7aA5kNGTesM=; b=tL4nuehXkN0pXyQYY8Be+p7DrjQ1O/1tcR7zifHauhPpGAKmK6WVl84GuUzjmjkowP enwQPH7gk2JXYA5CzmKYOP3PHmb8GY/U8NlVYNcCrE7+YQR8wAbaEBJUr556veYn8bwm YdKwiQ355g+xD62wwOVWpTQgmih5njzskRO4A5Fh+iWx8If4ItYwiI0XtiFDIwlJ97WC BiIunzVoDM6IaHU75K33SE5BNyFW+pN/3T1mXSzYLhN+mLIS9PJxPiiLQQSSOcp+kzCH oR+rWUqQP3eGypZDxP6NAhxu41/sy2EFXXZ/b0Y7KlCqB00MyoCZMSnFmbiHWWdVVl5u 4+Yw== X-Gm-Message-State: APjAAAUb6akHbJJi47odhbQGM8DkxcT/O6jgq/bZOWk0PIfKjaWpD5jL /jr4mY+/emrb0RLhob08JmE= X-Google-Smtp-Source: APXvYqzB4F+yS7f1sgEjUNcOjRCCmtgwl96RqnbPCksZpxp2Ya1m4QtKRIu6e88VZSMxmphd2yU8kg== X-Received: by 2002:aa7:9514:: with SMTP id b20mr20281567pfp.223.1565334656644; Fri, 09 Aug 2019 00:10:56 -0700 (PDT) Received: from suzukaze.ipads-lab.se.sjtu.edu.cn ([89.31.126.54]) by smtp.gmail.com with ESMTPSA id c26sm100738897pfr.172.2019.08.09.00.10.54 (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Fri, 09 Aug 2019 00:10:56 -0700 (PDT) From: Chuhong Yuan Cc: Ingo Molnar , Peter Zijlstra , linux-kernel@vger.kernel.org, Chuhong Yuan Subject: [PATCH v4 6/8] sched: Replace strncmp with str_has_prefix Date: Fri, 9 Aug 2019 15:10:51 +0800 Message-Id: <20190809071051.17387-1-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/sched/debug.c | 6 ++++-- kernel/sched/isolation.c | 11 +++++++---- 2 files changed, 11 insertions(+), 6 deletions(-) diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c index f7e4579e746c..a03900523e5d 100644 --- a/kernel/sched/debug.c +++ b/kernel/sched/debug.c @@ -102,10 +102,12 @@ static int sched_feat_set(char *cmp) { int i; int neg = 0; + size_t len; - if (strncmp(cmp, "NO_", 3) == 0) { + len = str_has_prefix(cmp, "NO_"); + if (len) { neg = 1; - cmp += 3; + cmp += len; } i = match_string(sched_feat_names, __SCHED_FEAT_NR, cmp); diff --git a/kernel/sched/isolation.c b/kernel/sched/isolation.c index ccb28085b114..ea2ead4b1906 100644 --- a/kernel/sched/isolation.c +++ b/kernel/sched/isolation.c @@ -141,16 +141,19 @@ __setup("nohz_full=", housekeeping_nohz_full_setup); static int __init housekeeping_isolcpus_setup(char *str) { unsigned int flags = 0; + size_t len; while (isalpha(*str)) { - if (!strncmp(str, "nohz,", 5)) { - str += 5; + len = str_has_prefix(str, "nohz,"); + if (len) { + str += len; flags |= HK_FLAG_TICK; continue; } - if (!strncmp(str, "domain,", 7)) { - str += 7; + len = str_has_prefix(str, "domain,"); + if (len) { + str += len; flags |= HK_FLAG_DOMAIN; continue; } -- 2.20.1