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=-2.4 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,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 042B0C2D0E5 for ; Sat, 28 Mar 2020 14:06:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CE1D5206E6 for ; Sat, 28 Mar 2020 14:06:40 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=joelfernandes.org header.i=@joelfernandes.org header.b="kShGLTXZ" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726449AbgC1OGk (ORCPT ); Sat, 28 Mar 2020 10:06:40 -0400 Received: from mail-qk1-f195.google.com ([209.85.222.195]:40302 "EHLO mail-qk1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726045AbgC1OGj (ORCPT ); Sat, 28 Mar 2020 10:06:39 -0400 Received: by mail-qk1-f195.google.com with SMTP id l25so14054098qki.7 for ; Sat, 28 Mar 2020 07:06:37 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=joelfernandes.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=yZlMnYD6JqijSy564Fn87fpjw+Y3itMay1NF67PRDIo=; b=kShGLTXZ9/1ypJmti9uE2QCKI+tWlrSzVk6cgWkeYRd4haLeUZDrDHXvwSS7rQX4Ji wVTTtAGngCgnEhumeW2mdSnS/tR8Ne2FzLgCTzixXqkN+4ASa3WRGMtz79anz4CpCKt1 ND7gKDEM+zwAcxtS1D0ASlVU0N9Tei5E1OWTI= 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:references :mime-version:content-disposition:in-reply-to:user-agent; bh=yZlMnYD6JqijSy564Fn87fpjw+Y3itMay1NF67PRDIo=; b=KehkmZoo3+/sO2hFX//2IIGzP959+IUc85089xxEdtRptRnf9Djgi78lGc+3Z+J3ND wXaer/V8ByMlAHDRt+hr7Ig6eugGHV/2LA+x+XFzV7gmG5Bxi2K56l55mai9c9qKoYTZ YU2j1givqi3H7/jRj3JYp9Y465wonWJMQqWnU6GSkQ6lEJ5eiLuN40uhYHbYoPo01tnU dBFsCiTNeXDS/KCsIX9AcA4dofgWNSZf/9TZytTe9JND3O61FyzVpRMVN7TSjERaX7GX rKvsdSNwQGLo8nIFspzNDVbFmh+NWU3y8GwkUHgezbWN1fSQI84AZ7xEJ6jaUEndALuy lvOw== X-Gm-Message-State: ANhLgQ078NjB0ojFjbuH7L/Ml1O1mfFkn+PD5imX3tddYE4agAQZertq 69NqRUFPqpcE1E0gF6xGeg6VcA== X-Google-Smtp-Source: ADFU+vvQLa1gK5s2WAC8iuBwK3tSpdtA4/uyjFRuaqfLuLFWmj6ncKwjq5JqYfByyZnjFVPq3a+4Fw== X-Received: by 2002:a37:9ec8:: with SMTP id h191mr4063670qke.260.1585404396878; Sat, 28 Mar 2020 07:06:36 -0700 (PDT) Received: from localhost ([2620:15c:6:12:9c46:e0da:efbf:69cc]) by smtp.gmail.com with ESMTPSA id w9sm5863186qkf.28.2020.03.28.07.06.35 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 28 Mar 2020 07:06:35 -0700 (PDT) Date: Sat, 28 Mar 2020 10:06:35 -0400 From: Joel Fernandes To: "Paul E. McKenney" Cc: Steven Rostedt , rcu@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-team@fb.com, mingo@kernel.org, jiangshanlai@gmail.com, dipankar@in.ibm.com, akpm@linux-foundation.org, mathieu.desnoyers@efficios.com, josh@joshtriplett.org, tglx@linutronix.de, peterz@infradead.org, dhowells@redhat.com, edumazet@google.com, fweisbec@gmail.com, oleg@redhat.com, Alexei Starovoitov , Andrii Nakryiko Subject: Re: [PATCH RFC v2 tip/core/rcu 14/22] rcu-tasks: Add an RCU Tasks Trace to simplify protection of tracing hooks Message-ID: <20200328140635.GA201808@google.com> References: <20200319001024.GA28798@paulmck-ThinkPad-P72> <20200319001100.24917-14-paulmck@kernel.org> <20200319154239.6d67877d@gandalf.local.home> <20200320002813.GL3199@paulmck-ThinkPad-P72> <20200319204838.1f78152a@gandalf.local.home> <20200320024152.GM3199@paulmck-ThinkPad-P72> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200320024152.GM3199@paulmck-ThinkPad-P72> User-Agent: Mutt/1.12.2 (2019-09-21) Sender: rcu-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: rcu@vger.kernel.org On Thu, Mar 19, 2020 at 07:41:53PM -0700, Paul E. McKenney wrote: > On Thu, Mar 19, 2020 at 08:48:38PM -0400, Steven Rostedt wrote: > > On Thu, 19 Mar 2020 17:28:13 -0700 > > "Paul E. McKenney" wrote: > > > > > Good point. If interrupts are disabled, it will need to use some > > > other mechanism. One approach is irqwork. Another is a timer. > > > > > > Suggestions? > > > > Ftrace and perf use irq_work, I would think that should work here too. > > Sounds good, will give it a go! And thank you for catching this! Since the the Tasks-RCU holdout thread is supposed to wake up periodically to scan holdout tasks anyway, can it not detect the end of the Trace-RCU grace period on its next wake up? Sorry if I missed something. thanks, - Joel