From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S936779Ab3DHKsI (ORCPT ); Mon, 8 Apr 2013 06:48:08 -0400 Received: from hydra.sisk.pl ([212.160.235.94]:54057 "EHLO hydra.sisk.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933985Ab3DHKsG (ORCPT ); Mon, 8 Apr 2013 06:48:06 -0400 From: "Rafael J. Wysocki" To: chenhc@lemote.com Cc: Greg KH , Andrew Morton , linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, Fuxin Zhang , stable@vger.kernel.org Subject: Re: [PATCH] PM/reboot: call syscore_shutdown() after disable_nonboot_cpus() Date: Mon, 08 Apr 2013 12:55:48 +0200 Message-ID: <11388244.eyJZJtFod3@vostro.rjw.lan> User-Agent: KMail/4.9.5 (Linux/3.9.0-rc4+; KDE/4.9.5; x86_64; ; ) In-Reply-To: <6c971a50f7639f17b1c419b6a885409b.squirrel@mail.lemote.com> References: <1365300854-3133-1-git-send-email-chenhc@lemote.com> <2582863.XOOaeZz0rz@vostro.rjw.lan> <6c971a50f7639f17b1c419b6a885409b.squirrel@mail.lemote.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="utf-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Monday, April 08, 2013 10:51:45 AM chenhc@lemote.com wrote: > > On Sunday, April 07, 2013 08:29:32 AM Greg KH wrote: > >> On Sun, Apr 07, 2013 at 10:46:00AM +0200, Rafael J. Wysocki wrote: > >> > On Sunday, April 07, 2013 10:14:14 AM Huacai Chen wrote: > >> > > As commit 40dc166c (PM / Core: Introduce struct syscore_ops for core > >> > > subsystems PM) say, syscore_ops operations should be carried with > >> one > >> > > CPU on-line and interrupts disabled. However, after commit f96972f2d > >> > > (kernel/sys.c: call disable_nonboot_cpus() in kernel_restart()), > >> > > syscore_shutdown() is called before disable_nonboot_cpus(), so break > >> > > the rules. We have a MIPS machine with a 8259A PIC, and there is an > >> > > external timer (HPET) linked at 8259A. Since 8259A has been shutdown > >> > > too early (by syscore_shutdown()), disable_nonboot_cpus() runs > >> without > >> > > timer interrupt, so it hangs and reboot fails. This patch call > >> > > syscore_shutdown() a little later (after disable_nonboot_cpus()) to > >> > > avoid reboot failure, this is the same way as poweroff does. > >> > > > >> > > BTW, add disable_nonboot_cpus() in kernel_halt() for consistency. > >> > > > >> > > Signed-off-by: Huacai Chen > >> > > Cc: > >> > > >> > While I agree with the changes, I'm not sure if I'm the right > >> maintainer, > >> > as this isn't really PM code. > >> > > >> > Andrew, should I take this? > >> > >> Andrew is on vacation for a few weeks, so you might need to take this > >> through your tree. > > > > OK > > > > But, it looks like we should actually disable interrupts on the remaining > > CPU after we've called disable_nonboot_cpus() so that the > > syscore_shutdown() > > assumptions are satisfied which the patch doesn't do. > > > > Chen (I apologize if that's not the right part of your full name to use > > here), > > do you think that's not necessary and if so, then for what reason? > > Reboot and poweroff are both OK after I move syscore_shutdown(), I also don't > know whether we should disable interrupts. Since you are the author of > commit 40dc166c (PM / Core: Introduce struct syscore_ops for core subsystems > PM), please tell me why syscore_shutdown() need interrupt disabled? Well, the syscore_ callbacks generally do things that may go wrong when an interrupt comes in while they are being done. At least that's what happens for the suspend/resume syscore_ callbacks, but I'm not really sure about the shutdown ones. I suppose we can leave it as is for the time being. At least I'm not aware of any problems related to that. Thanks, Rafael -- I speak only for myself. Rafael J. Wysocki, Intel Open Source Technology Center.