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=-5.8 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,URIBL_BLOCKED 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 77BC2C433E6 for ; Thu, 21 Jan 2021 14:59:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 30BC3239D4 for ; Thu, 21 Jan 2021 14:59:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732009AbhAUO7W (ORCPT ); Thu, 21 Jan 2021 09:59:22 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58764 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731816AbhAUO6V (ORCPT ); Thu, 21 Jan 2021 09:58:21 -0500 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 44B72C061786 for ; Thu, 21 Jan 2021 06:57:31 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.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=e8eyXWv9TNfB8rTh4a0YjdR85qyV5f8Yl1cBULzvB1A=; b=SirJxrLF4Q45UKXQW8vX2OaUoo dt5iIN9oMNbsr1xkkcMB3aVi8+ExgY6q1468WgnHos9mQ8nI3i4gQ8IifT2hTvBhUdlY8IEfRSp2K RSK7xY09cocu+8qT6oQShk9rnnf4Tioal6P0Msn73xKCmFvSudHZhW0Tpf7PTwWXy/zLFtFyrWWlG LdAfP1Kn5VsTXA3c7IXrjPa2AoPikecfz9IqJtO98JTMbMkqvwrwbHfyzRc82tvMrTKqfbzqiGi8B M9mUtMEoiDTGL/NRrXTM7OF0/MqkQImg3ZGbrfXUMgtgx7nce2j1U87OgW69H7uuErdxIktagIkFm TU+CwntA==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.94 #2 (Red Hat Linux)) id 1l2bOV-00HAtT-2v; Thu, 21 Jan 2021 14:57:14 +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 293EF303A02; Thu, 21 Jan 2021 15:57:04 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id E71BD2028F0C2; Thu, 21 Jan 2021 15:57:03 +0100 (CET) Date: Thu, 21 Jan 2021 15:57:03 +0100 From: Peter Zijlstra To: vincent.donnefort@arm.com Cc: tglx@linutronix.de, linux-kernel@vger.kernel.org, valentin.schneider@arm.com Subject: Re: [PATCH 4/4] cpu/hotplug: Fix CPU down rollback Message-ID: References: <1610385047-92151-1-git-send-email-vincent.donnefort@arm.com> <1610385047-92151-5-git-send-email-vincent.donnefort@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1610385047-92151-5-git-send-email-vincent.donnefort@arm.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jan 11, 2021 at 05:10:47PM +0000, vincent.donnefort@arm.com wrote: > From: Vincent Donnefort > > After the AP brought itself down to CPUHP_TEARDOWN_CPU, the BP will finish > the job. The steps left are as followed: > > +--------------------+ > | CPUHP_TEARDOWN_CPU | -> If fails state is CPUHP_TEARDOWN_CPU > +--------------------+ > | ATOMIC STATES | -> Cannot Fail > +--------------------+ > | CPUHP_BRINGUP_CPU | -> Cannot fail > +--------------------+ > | ... | > | ... | -> Can fail and rollback These are the PREPARE/DEAD states, right? It would be _really_ daft for a DEAD notifier to fail. But yeah, I suppose that if it does, it will indeed end up in CPUHP_AP_ONLINE_IDLE. Do we want to WARN when a DEAD notifier fails?