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=-4.5 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, FSL_HELO_FAKE,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS, URIBL_BLOCKED,USER_AGENT_MUTT 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 1BE02C04EB9 for ; Mon, 3 Dec 2018 09:15:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CF50221479 for ; Mon, 3 Dec 2018 09:15:28 +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="oc1RJ7AS" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org CF50221479 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726046AbeLCJPh (ORCPT ); Mon, 3 Dec 2018 04:15:37 -0500 Received: from mail-wr1-f67.google.com ([209.85.221.67]:40789 "EHLO mail-wr1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725874AbeLCJPg (ORCPT ); Mon, 3 Dec 2018 04:15:36 -0500 Received: by mail-wr1-f67.google.com with SMTP id p4so11262223wrt.7 for ; Mon, 03 Dec 2018 01:15:25 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=iQaEkHRaot1wBFKxlKh+ZrWlG+RRqLhA+1jrGGt8gFI=; b=oc1RJ7ASedxO4KYiamh3dO34V6Pe2aJj/8ofYGBvnutmi7b6z9Ep5fPQctW8vpI3y4 qtUlpvdV0CQh4YMM9+i1yZ3VKwOKIdDD/01XMJOySmEazlJgZ5R74nIyHlDpDljrsDgJ e9al/nVMWK7x9iBY2XqeYTjgNEqSJdKoFsmlCZtR0fIlHX4WNjbciuBPZFTbErpGnl/G GtDdnN99ESc9wSMIGH4BwY6sdt/LnAy/oZ1elNiXfDozr/P33dWh26jUe2G29z0e3U9k YPunzyol3AQnyDlzN6h2Vjuz/yaA10Xn5Cgs8MnvLfL61nQ93Lt3UE3eLKHW9j8DKQQg p5Zw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:date:from:to:cc:subject:message-id :references:mime-version:content-disposition:in-reply-to:user-agent; bh=iQaEkHRaot1wBFKxlKh+ZrWlG+RRqLhA+1jrGGt8gFI=; b=j9FGdMqZ46TI6XUbAJMyT2DH5Vtoq7NJ2CxwDp0LzgXKycmCCfb286JILvl1dGLuZv mYpjY8ojGzReuFNUxpkYwUVKqbJqNOSiQ/PmoKNNft++v9fIsfYQMvme44BPNs0nW+On D40YmZGQbFrf7rW9juoX4c64n/+4l0OvTfmoaOhTA/LWtIoPJ/dR1Of1upGWz5SlQGy0 9QolyQSD3Ola9TemYGU9E7bx4pRjOB+aEGFFtDmCfTEHVA/SwJ1X13fsYqLwbjqREmy3 QR8jxYIQjIwna6+oeXG9ueo1YlDxU8wxEFss+DKuG5//2ffBAoTJy1KGSIdWIy/TvxYL 5+ug== X-Gm-Message-State: AA+aEWazblYgwzP4NgVlYxKxGHs5u3NHIWV46vr1OHhH6Q//TlqaqqCr Tvt7g+wr6S+ubZVxQ/ntpns= X-Google-Smtp-Source: AFSGD/VPIYXPQG3O7+8BsG7Z7v5j1fi6Nj8lYLLRqtlcWOaFztIxikNApX+y8loeNaVc0gqWgaQ/rQ== X-Received: by 2002:adf:8264:: with SMTP id 91mr12679104wrb.312.1543828525112; Mon, 03 Dec 2018 01:15:25 -0800 (PST) Received: from gmail.com (2E8B0CD5.catv.pool.telekom.hu. [46.139.12.213]) by smtp.gmail.com with ESMTPSA id h4sm11655611wrt.66.2018.12.03.01.15.23 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Mon, 03 Dec 2018 01:15:24 -0800 (PST) Date: Mon, 3 Dec 2018 10:15:22 +0100 From: Ingo Molnar To: Wen Yang Cc: Thomas Gleixner , Konrad Rzeszutek Wilk , Josh Poimboeuf , linux-kernel@vger.kernel.org, zhong.weidong@zte.com.cn, "Peter Zijlstra (Intel)" , Peter Zijlstra , Mukesh Ojha , Peter Zijlstra Subject: Re: [PATCH] cpu: Bool tests don't need comparisons Message-ID: <20181203091522.GC2516@gmail.com> References: <20181201080444.9305-1-wen.yang99@zte.com.cn> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181201080444.9305-1-wen.yang99@zte.com.cn> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Wen Yang wrote: > This is the patch to the file cpu.c > which fixes the following coccinelle warning: > > WARNING: Comparison to bool > > Signed-off-by: Wen Yang > CC: Thomas Gleixner > CC: Ingo Molnar > CC: Konrad Rzeszutek Wilk > CC: Josh Poimboeuf > CC: "Peter Zijlstra (Intel)" > CC: Peter Zijlstra > CC: Mukesh Ojha > CC: linux-kernel@vger.kernel.org > --- > kernel/cpu.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/kernel/cpu.c b/kernel/cpu.c > index 91d5c38eb7e5..5bdd7e150a11 100644 > --- a/kernel/cpu.c > +++ b/kernel/cpu.c > @@ -1650,7 +1650,7 @@ int __cpuhp_state_add_instance_cpuslocked(enum cpuhp_state state, > lockdep_assert_cpus_held(); > > sp = cpuhp_get_step(state); > - if (sp->multi_instance == false) > + if (!sp->multi_instance) > return -EINVAL; > This is a *totally* bogus explanation. This is an equivalent pattern to '== 0' which is commonly used. The patch is still doing the right thing, but only accidentally, for another reason, it's because we are using ->multi_instance in an inconsistent fashion: kernel/cpu.c: if (!step->multi_instance) { kernel/cpu.c: if (sp->multi_instance == false) kernel/cpu.c: if (!sp->multi_instance) kernel/cpu.c: if (sp->multi_instance) { But that's really just by accident - if all usages were of the '== true/false' pattern then this wouldn't be necessary. Thanks, Ingo