On Thu, Jan 24, 2013 at 9:14 PM, Greg Kroah-Hartman <gre...@linuxfoundation.org> wrote: > On Thu, Jan 24, 2013 at 07:59:01PM -0700, Bjorn Helgaas wrote: >> [+cc Greg for driver core] >> >> On Fri, Jan 25, 2013 at 10:13:03AM +0900, Joonsoo Kim wrote: >> > 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 <js1...@gmail.com> 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 <t...@linutronix.de> >> > > > Cc: Ingo Molnar <mi...@redhat.com> >> > > > Cc: "H. Peter Anvin" <h...@zytor.com> >> > > > Signed-off-by: Joonsoo Kim <js1...@gmail.com> >> > > > >> > > > 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. >> >> I see. pci_bus_type.p is initialized by __bus_register() in this path: >> >> pci_driver_init # postcore_initcall >> bus_register(&pci_bus_type) >> __bus_register >> priv = kzalloc(sizeof(struct subsys_private)) >> bus->p = priv >> klist_init(&priv->klist_devices, klist_devices_get, klist_devices_put) >> >> I was hoping we could statically initialize the klist, but that doesn't >> seem likely. >> >> But I wonder if we could do something like the following. If we could, >> then callers wouldn't have to worry about whether or not the bus has been >> initialized. > > <snip> > > I have no objection to that patch, but really, someone wants to call > pci_find_device() before PCI is initialized? Can't that be fixed > instead, as that is the root problem, not the driver core. > > But, to paper over your subsystem's bugs, I guess I can take it :)
The caller is in the native_machine_emergency_restart() path. Joonsoo's original patch does what I think you're suggesting: >> > > > + /* 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 think it's sort of ugly to check system_state before using pci_get_device(), and there's not really an obvious connection between system_state and PCI initialization. But if you prefer that, Joonsoo's original patch is fine with me. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/