From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S936438Ab3DHOaD (ORCPT ); Mon, 8 Apr 2013 10:30:03 -0400 Received: from mail.lemote.com ([222.92.8.138]:52229 "EHLO mail.lemote.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S935372Ab3DHOaA (ORCPT ); Mon, 8 Apr 2013 10:30:00 -0400 Message-ID: <3557860596dc88c320d7a477a268052f.squirrel@mail.lemote.com> In-Reply-To: <11388244.eyJZJtFod3@vostro.rjw.lan> References: <1365300854-3133-1-git-send-email-chenhc@lemote.com> <2582863.XOOaeZz0rz@vostro.rjw.lan> <6c971a50f7639f17b1c419b6a885409b.squirrel@mail.lemote.com> <11388244.eyJZJtFod3@vostro.rjw.lan> Date: Mon, 8 Apr 2013 22:29:46 +0800 Subject: Re: [PATCH] PM/reboot: call syscore_shutdown() after disable_nonboot_cpus() From: chenhc@lemote.com To: "Rafael J. Wysocki" Cc: "Greg KH" , "Andrew Morton" , linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, "Fuxin Zhang" , stable@vger.kernel.org User-Agent: SquirrelMail/1.4.22 MIME-Version: 1.0 Content-Type: text/plain;charset=gb2312 Content-Transfer-Encoding: 8bit X-Priority: 3 (Normal) Importance: Normal 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. OK, linux-3.0, 3.2 and 3.4 -stable branch also need this patch because they also have merged the commit f96972f2d (kernel/sys.c: call disable_nonboot_cpus() in kernel_restart()) > > Thanks, > Rafael > > > -- > I speak only for myself. > Rafael J. Wysocki, Intel Open Source Technology Center. >