From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753749Ab3AYBNJ (ORCPT ); Thu, 24 Jan 2013 20:13:09 -0500 Received: from LGEMRELSE1Q.lge.com ([156.147.1.111]:52380 "EHLO LGEMRELSE1Q.lge.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750970Ab3AYBNF (ORCPT ); Thu, 24 Jan 2013 20:13:05 -0500 X-AuditID: 9c93016f-b7b70ae000000e36-7a-5101dc1dfc05 Date: Fri, 25 Jan 2013 10:13:03 +0900 From: Joonsoo Kim To: Bjorn Helgaas Cc: "H. Peter Anvin" , linux-kernel@vger.kernel.org, x86@kernel.org, Thomas Gleixner , Ingo Molnar Subject: Re: [PATCH] x86, reboot: skip reboot_fixups in early boot phase Message-ID: <20130125011303.GA3401@lge.com> References: <1356702623-9430-1-git-send-email-js1304@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) X-Brightmail-Tracker: AAAAAA== Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, Bjorn. On Thu, Jan 24, 2013 at 10:45:13AM -0700, Bjorn Helgaas wrote: > On Fri, Dec 28, 2012 at 6:50 AM, Joonsoo Kim wrote: > > During early boot phase, PCI bus subsystem is not yet initialized. > > If panic is occured in early boot phase and panic_timeout is set, > > code flow go into emergency_restart() and hit mach_reboot_fixups(), then > > encounter another panic. When second panic, we can't hold a panic_lock, so > > code flow go into panic_smp_self_stop() which prevent system to restart. > > > > For avoid second panic, skip reboot_fixups in early boot phase. > > It makes panic_timeout works in early boot phase. > > > > Cc: Thomas Gleixner > > Cc: Ingo Molnar > > Cc: "H. Peter Anvin" > > Signed-off-by: Joonsoo Kim > > > > diff --git a/arch/x86/kernel/reboot_fixups_32.c b/arch/x86/kernel/reboot_fixups_32.c > > index c8e41e9..b9b8ec9 100644 > > --- a/arch/x86/kernel/reboot_fixups_32.c > > +++ b/arch/x86/kernel/reboot_fixups_32.c > > @@ -89,6 +89,10 @@ void mach_reboot_fixups(void) > > if (in_interrupt()) > > return; > > > > + /* During early boot phase, PCI is not yet initialized */ > > + if (system_state == SYSTEM_BOOTING) > > + return; > > + > > for (i=0; i < ARRAY_SIZE(fixups_table); i++) { > > cur = &(fixups_table[i]); > > dev = pci_get_device(cur->vendor, cur->device, NULL); > > I guess you're saying that if we call pci_get_device() too early, it > panics? Did you figure out why that happens? > > If we call pci_get_device() before PCI has been initialized, it would > be good if it just returned NULL, indicating that we didn't find any > matching device. I looked briefly, and I thought that's what would > happen, but apparently I'm missing something. In bus_find_device(), klist_iter_init_node() is called with @bus->p->klist_device. Before initialization, bus->p is NULL, so panic is occured. > Bjorn > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/