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=-8.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 00FC4C433E2 for ; Tue, 26 May 2020 21:57:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CD0DD20888 for ; Tue, 26 May 2020 21:57:24 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="uH/9ULXd" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2403820AbgEZV5Y (ORCPT ); Tue, 26 May 2020 17:57:24 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60448 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2390780AbgEZV5X (ORCPT ); Tue, 26 May 2020 17:57:23 -0400 Received: from mail-ej1-x642.google.com (mail-ej1-x642.google.com [IPv6:2a00:1450:4864:20::642]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1F889C061A0F for ; Tue, 26 May 2020 14:57:23 -0700 (PDT) Received: by mail-ej1-x642.google.com with SMTP id l27so3397825ejc.1 for ; Tue, 26 May 2020 14:57:23 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:reply-to:references:mime-version :content-disposition:in-reply-to:user-agent; bh=nBxgS/luVHAeXT0Vdy997lAaqi3EXhdBrjkjeD26BA4=; b=uH/9ULXdDZTF5dDETLzY5uKo11ZJgkabQ6hKp/LAKfnLibCI7YGSaFVDqlk6BjBBX+ 9v/qkm9HoW5ERyU8cnYq+T3gGpaz1ikJkfATPJtQVIDTBdqYBsGkFsEhmG9hClV037He 2OPG2HsI9DmjoRrNINLyx9TtDvM2zdJ3BUxz8ylIBFJ8a2QQHl1rVRsRp2IBf6t2/aAh tUYWxlsYkP2jMfWEPi39E46cwDIwXzsI1HF33yB5P0MsobmMUeSgWATR8V72uTb8yoa1 3Zbv2X4ugtZcY5E6x/RcDha64PX3dBPljeq+Pi8O/lpUACeSLFq0PTriONOiIjZHCjwl 4z7w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:reply-to :references:mime-version:content-disposition:in-reply-to:user-agent; bh=nBxgS/luVHAeXT0Vdy997lAaqi3EXhdBrjkjeD26BA4=; b=bNkPxfOk56brs99GiGdyXlodNLhTGI/MEsgAQHAzXVvHP32hU3+G6M0+5Lzgq6X+XN goLTJmaDMy/iwuxl+laBj4kwL5AnFfUzwMp5G4O00+DWPUZL4uk8VSIN18Jtj4XMp9ur m5Pq/3Xgs1VVOlKiL7U5hr1FcjzFMVbwAbaMBmogcyKn3BRqtgIns1sYzDyjTJX4UBLN 875MMnj0XsBMT2BXUCY7PIua3mIzebtj48fRNW9ZdmFZBN0qZL47KFjoG3Vz3HzWDV+2 i6wShq3V2GrPUS9o7vkBbQG9Xj8w8Kixxko42u01+7vsyud7aols5qn68/JaJXrjJ8fl GSDg== X-Gm-Message-State: AOAM5312DwyhP5pNAb0QM617iGkllO3wX+1Yn5TpmDB8HjUJplyIXgf9 1xnoeQNTjtqH/vqeQZi/BPg= X-Google-Smtp-Source: ABdhPJy7dXpaYaf6FVtHj8sPeZC8u66KiKuj3nr3xoEslObuORIp5/0XVhRvUzp7VVZpCNQmifl4hA== X-Received: by 2002:a17:906:b7cd:: with SMTP id fy13mr1249808ejb.133.1590530241865; Tue, 26 May 2020 14:57:21 -0700 (PDT) Received: from localhost ([185.92.221.13]) by smtp.gmail.com with ESMTPSA id s8sm964443edj.64.2020.05.26.14.57.20 (version=TLS1_2 cipher=ECDHE-ECDSA-CHACHA20-POLY1305 bits=256/256); Tue, 26 May 2020 14:57:20 -0700 (PDT) Date: Tue, 26 May 2020 21:57:20 +0000 From: Wei Yang To: Andy Shevchenko Cc: Wei Yang , akpm@linux-foundation.org, christian.brauner@ubuntu.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH] bitops: use the same mechanism for get_count_order[_long] Message-ID: <20200526215720.42rs547h2vq6xgl5@master> Reply-To: Wei Yang References: <20200525215958.21653-1-richard.weiyang@gmail.com> <20200526070457.GI1634618@smile.fi.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200526070457.GI1634618@smile.fi.intel.com> User-Agent: NeoMutt/20170113 (1.7.2) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, May 26, 2020 at 10:04:57AM +0300, Andy Shevchenko wrote: >On Mon, May 25, 2020 at 09:59:58PM +0000, Wei Yang wrote: >> These two functions share the same logic. > >So, same comment. Please, add test first, make sure it works on current kernel, >then after your patch applied, and send it as a series, thanks! > >P.S. W/o test code looks good, but based on my experience I'm very suspicious >about "small" changes that may lead to big issues. Hope you understand my point. > Sure, I see your point. >> Signed-off-by: Wei Yang >> --- >> include/linux/bitops.h | 8 +++----- >> 1 file changed, 3 insertions(+), 5 deletions(-) >> >> diff --git a/include/linux/bitops.h b/include/linux/bitops.h >> index 5b5609e81a84..80703ef27aee 100644 >> --- a/include/linux/bitops.h >> +++ b/include/linux/bitops.h >> @@ -188,12 +188,10 @@ static inline unsigned fls_long(unsigned long l) >> >> static inline int get_count_order(unsigned int count) >> { >> - int order; >> + if (count == 0) >> + return -1; >> >> - order = fls(count) - 1; >> - if (count & (count - 1)) >> - order++; >> - return order; >> + return fls(--count); >> } >> >> /** >> -- >> 2.23.0 >> > >-- >With Best Regards, >Andy Shevchenko > -- Wei Yang Help you, Help me