From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753189AbaEWPNE (ORCPT ); Fri, 23 May 2014 11:13:04 -0400 Received: from casper.infradead.org ([85.118.1.10]:50910 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751260AbaEWPND (ORCPT ); Fri, 23 May 2014 11:13:03 -0400 Date: Fri, 23 May 2014 17:12:52 +0200 From: Peter Zijlstra To: "Srivatsa S. Bhat" Cc: Frederic Weisbecker , tglx@linutronix.de, mingo@kernel.org, tj@kernel.org, rusty@rustcorp.com.au, akpm@linux-foundation.org, hch@infradead.org, mgorman@suse.de, riel@redhat.com, bp@suse.de, rostedt@goodmis.org, mgalbraith@suse.de, ego@linux.vnet.ibm.com, paulmck@linux.vnet.ibm.com, oleg@redhat.com, rjw@rjwysocki.net, linux-kernel@vger.kernel.org Subject: Re: [PATCH v6 2/3] CPU hotplug, stop-machine: Plug race-window that leads to "IPI-to-offline-CPU" Message-ID: <20140523151252.GE30445@twins.programming.kicks-ass.net> References: <20140523101134.17924.31463.stgit@srivatsabhat.in.ibm.com> <20140523101216.17924.62447.stgit@srivatsabhat.in.ibm.com> <20140523132250.GA1768@localhost.localdomain> <537F5F0F.5050802@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="HFKwn2g6R1ux/FzN" Content-Disposition: inline In-Reply-To: <537F5F0F.5050802@linux.vnet.ibm.com> User-Agent: Mutt/1.5.21 (2012-12-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --HFKwn2g6R1ux/FzN Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Fri, May 23, 2014 at 08:15:35PM +0530, Srivatsa S. Bhat wrote: > >> + * During CPU offline, we don't want the other CPUs to send > >> + * IPIs to the active_cpu (the outgoing CPU) *after* it has > >> + * disabled interrupts (because, then it will notice the IPIs > >> + * only after it has gone offline). We can prevent this by > >> + * making the other CPUs disable their interrupts first - that > >> + * way, they will run the stop-machine code with interrupts > >> + * disabled, and hence won't send IPIs after that point. That's complete nonsense, you can send IPIs all you want with interrupts disabled. --HFKwn2g6R1ux/FzN Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.12 (GNU/Linux) iQIcBAEBAgAGBQJTf2VtAAoJEHZH4aRLwOS6qrIP/RJV36pvvkDjsNCZIxogeITj KX2G+LHCXIgMAjlgHbWIGcs7+aV2lHi2jht1A27ezbshYLJ+TsdZHBHM1dUpaFVg Nd3fiv64f7BO6dSeho4k1vAAsttZmEKA1HC5kulUBDU84CQR3e1Pb0+uJ5bOev1g 7lny5pQB67ltl8vyHwz8lZ+AkWz/Pk8cp84fRDXbTgXjlQTs2wyZ1m2gYusTVwmV 56biMG0gK7IlZ6QwFlhQpm0GfOm8mwo4/HaWfpd2xf9vRbtvdrreLMzSuwaO7eaH B5tta4M/ru78YBk95k4uWsWfs5lT9yinB09p3J8pznnWKylCqyTBeQqCeDA0uQiH JTfKzAz4hr0XPkeQci1AaiJd9hTC5zdyLo8CbZEd8+ZOiPeN2kylzvONXORw1fIj avGc14aDw1vYyTeAQ/XHq6NYkC0e0jXaj2x0SYEEXoY+Q5dQ7HM39Ab4lYpqkdfZ +YFsxXuZjfN1bHpy4dyLXY+1Ra6clBiCWFI+Kb7rkA/GycyXkUnvBk9h77fAuGCR aZJpEYLI+sm+jEWJtE5EYNPenS4j1PiZ9Aq+6TJ4/M+tQbgvaXv4vRlWAb3Q82eD m6TJbqsaAB3I9d0i/7oOWEmKx9USLn2C9xoVJzfKn7gW2MpYqjRc+D2X6MnE/5QZ x/qhL4koa0KVadfQ8g3Y =pkxY -----END PGP SIGNATURE----- --HFKwn2g6R1ux/FzN--