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=-3.9 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,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 A1DDFC4727C for ; Tue, 29 Sep 2020 14:50:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1B9FF2076B for ; Tue, 29 Sep 2020 14:50:04 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="mGxGxYrO" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728942AbgI2OuD (ORCPT ); Tue, 29 Sep 2020 10:50:03 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40200 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727328AbgI2OuC (ORCPT ); Tue, 29 Sep 2020 10:50:02 -0400 Received: from merlin.infradead.org (merlin.infradead.org [IPv6:2001:8b0:10b:1231::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3D5FEC061755 for ; Tue, 29 Sep 2020 07:50:02 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=QfNS7kmBNQ3K4ORpreZAzPxbXwgj+XL6qIvXBNr08X4=; b=mGxGxYrOkYHUlLWtDhpJ8xBYx9 pW03Xet+BVe68mn0pBWEvEIyPLTM+nOqaZK6NrB1m9VOliWy8wN57iX1Qz4wQmLNwAMfy+RRlIAsl DR4/GKkinJWXw4N42fn/y3xqv8bf9WW+PCkpCvF+FaSbrxLRfOHjllw5mo0ps1CaJr0F4KqX6BK5J VB+UhLDubUktXzqkRmC4MSv7HYCSfuiSfjQsNoCSXX49oIC9CCDcG/aUEpVYhrZT0J3KT3rOmIudh 5PBdctEt1hGBi2WQbNfBWJyuVhXM506d6dKg/XteURiJAVeLkMP8KCwD2PS3GLRxApFaiUxWdLDyq zNSIEUHA==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1kNGx1-0006R1-PW; Tue, 29 Sep 2020 14:49:55 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 5ACA0300F7A; Tue, 29 Sep 2020 16:49:54 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id ED7F5210E84D0; Tue, 29 Sep 2020 16:49:53 +0200 (CEST) Date: Tue, 29 Sep 2020 16:49:53 +0200 From: Peter Zijlstra To: Steven Rostedt Cc: Paul McKenney , linux-kernel@vger.kernel.org, Thomas Gleixner , Ingo Molnar , kim.phillips@amd.com Subject: Re: [PATCH] rcu,ftrace: Fix ftrace recursion Message-ID: <20200929144953.GP2628@hirez.programming.kicks-ass.net> References: <20200929113340.GN2628@hirez.programming.kicks-ass.net> <20200929103620.06762622@gandalf.local.home> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200929103620.06762622@gandalf.local.home> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Sep 29, 2020 at 10:36:20AM -0400, Steven Rostedt wrote: > > +notrace bool rcu_is_watching(void) > > { > > bool ret; > > > > I think the patch I suggested is more suitable. Both, with only your patch we'd still take the pointless mcount call, which is then pure overhead.