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=-2.1 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 DF44BC2BA83 for ; Wed, 12 Feb 2020 15:02:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B7FFE2073C for ; Wed, 12 Feb 2020 15:02:39 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="iK5CEFVR" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728513AbgBLPCi (ORCPT ); Wed, 12 Feb 2020 10:02:38 -0500 Received: from bombadil.infradead.org ([198.137.202.133]:43304 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727231AbgBLPCh (ORCPT ); Wed, 12 Feb 2020 10:02:37 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.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=FaxeSXwVb9YdybUdnSUzUuefptnpP1pWk8I0wE1Oxzo=; b=iK5CEFVRW9fYTbRCi9CnjsGQfB uVCamwQdLUMJVwpRf1eQtmWuO9Qj/M/kZySXlUMYjzNM4uCxkJADTlqAcB7q4bjo4xF5ch9gbAkUm zPxzPqocEgc/coGG0VoB/fK9XoXmWH2JTNPhcAAOXflURp3evLfpjGP15o+fWaB+GUJ2lRzvUuG45 43y57IhbEJ/PAANBIhWtTNqN+xn9Aje5JVdp1HEA/khkpqbeWDf4S8/UMTZS74qMOjpm3gjf+MXa1 sZnoyTwWBt8UYDSQjczJnjR3MAAn33C4bu+3mgKweKYxehnoJ0OWcBRaLx3cz5IxPN/qfIXNs4+Ey bJDw3QLw==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1j1tWo-00061G-T4; Wed, 12 Feb 2020 15:02:15 +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 E0ADA30066E; Wed, 12 Feb 2020 16:00:22 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id DE4CF2032662E; Wed, 12 Feb 2020 16:02:11 +0100 (CET) Date: Wed, 12 Feb 2020 16:02:11 +0100 From: Peter Zijlstra To: Steven Rostedt Cc: linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, mingo@kernel.org, joel@joelfernandes.org, gregkh@linuxfoundation.org, gustavo@embeddedor.com, tglx@linutronix.de, paulmck@kernel.org, josh@joshtriplett.org, mathieu.desnoyers@efficios.com, jiangshanlai@gmail.com Subject: Re: [PATCH 4/8] sched,rcu,tracing: Mark preempt_count_{add,sub}() notrace Message-ID: <20200212150211.GS14897@hirez.programming.kicks-ass.net> References: <20200212093210.468391728@infradead.org> <20200212094107.838108888@infradead.org> <20200212092417.04c3da8c@gandalf.local.home> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200212092417.04c3da8c@gandalf.local.home> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Feb 12, 2020 at 09:24:17AM -0500, Steven Rostedt wrote: > On Wed, 12 Feb 2020 10:32:14 +0100 > Peter Zijlstra wrote: > > > Because of the requirement that no tracing happens until after we've > > incremented preempt_count, see nmi_enter() / trace_rcu_enter(), mark > > these functions as notrace. > > I actually depend on these function being traced. Why? They already have a tracepoint inside. > We do have > "preempt_enable_notrace()" and "preempt_disable_notrace()" for places > that shouldn't be traced. Can't we use those? (or simply > __preempt_count_add()) in the nmi_enter() code instead? (perhaps create > a preempt_count_add_notrace()). My initial patch has __preempt_count_add/sub() in, but then I figured someone would go complain the tracepoint would go missing.