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 EA836C352A3 for ; Tue, 11 Feb 2020 15:30:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BD6F1208C3 for ; Tue, 11 Feb 2020 15:30:12 +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="VUKw3Mu9" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729305AbgBKPaM (ORCPT ); Tue, 11 Feb 2020 10:30:12 -0500 Received: from bombadil.infradead.org ([198.137.202.133]:40102 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728294AbgBKPaL (ORCPT ); Tue, 11 Feb 2020 10:30:11 -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=xs1yi8tH5NlwpQTjZ5mWrKCjszSGc2Crjq6zFwHP5fM=; b=VUKw3Mu9CU7DXAAvFmKAUbkx3e 4Yp/jolurw1aMjjGZClbb0hlWAw02eoatGweEGv0/IyLTZjaboZ7RqegsOFaJgc0AnofCmXmZEVu5 mFvNTPOrsxPaEmGu7mSw3h6wZL+dtNjou3OzgP6dBDXHkYtF313+58eGXpAZAnL23Oj+eCfCudHUu djc+jBCwDWDwHVH4s2DgVOvxtEWxht91tkG+0e0Gbd0nyAomjrCWaOTDoRUzAAAxN0Cj91+RasqdW FIYNfc+pDlfESAkVhelzfHJdvOJRF4r1CAQjmh9fxCumgzxDiAtLF5xoddmEXW+o2VITkyC8onb3E xWfrraJQ==; 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 1j1XTw-0003ds-CQ; Tue, 11 Feb 2020 15:29:48 +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 78C7930066E; Tue, 11 Feb 2020 16:27:56 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 13C8220148940; Tue, 11 Feb 2020 16:29:45 +0100 (CET) Date: Tue, 11 Feb 2020 16:29:45 +0100 From: Peter Zijlstra To: Steven Rostedt Cc: LKML , Ingo Molnar , "Joel Fernandes (Google)" , Greg Kroah-Hartman , "Gustavo A. R. Silva" , Thomas Gleixner , "Paul E. McKenney" , Josh Triplett , Mathieu Desnoyers , Lai Jiangshan Subject: Re: [PATCH] tracing/perf: Move rcu_irq_enter/exit_irqson() to perf trace point hook Message-ID: <20200211152945.GW14946@hirez.programming.kicks-ass.net> References: <20200210170643.3544795d@gandalf.local.home> <20200211114954.GK14914@hirez.programming.kicks-ass.net> <20200211090503.68c0d70f@gandalf.local.home> <20200211150532.GU14914@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200211150532.GU14914@hirez.programming.kicks-ass.net> 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 Tue, Feb 11, 2020 at 04:05:32PM +0100, Peter Zijlstra wrote: > So we haz: > > | #define nmi_enter() \ > | do { \ > | arch_nmi_enter(); \ > > arm64 only, lets ignore for now > > | printk_nmi_enter(); \ > > notrace > > | lockdep_off(); \ > > notrace > > | ftrace_nmi_enter(); \ > > !notrace !!! > > | BUG_ON(in_nmi()); \ > | preempt_count_add(NMI_OFFSET + HARDIRQ_OFFSET);\ > > lets make this __preempt_count_add() ASAP ! preempt_count_add() first frobs the actual preempt_count and then does the trace, so that might just work. But it does need a notrace annotation, I'm thinking, because calling into the function tracer _before_ we do the preempt_count increment is irrecoverable crap. > | rcu_nmi_enter(); \ > > are you _really_ sure you want to go trace that ?!? > > | trace_hardirq_enter(); \ > | } while (0) > >