On 06/14/2013 10:12 PM, Rafael J. Wysocki wrote: > On Friday, June 14, 2013 09:57:15 PM Jiang Liu wrote: >> On 06/14/2013 08:23 PM, Rafael J. Wysocki wrote: >>> On Thursday, June 13, 2013 09:59:44 PM Rafael J. Wysocki wrote: >>>> On Friday, June 14, 2013 12:32:25 AM Jiang Liu wrote: >>>>> Current ACPI glue logic expects that physical devices are destroyed >>>>> before destroying companion ACPI devices, otherwise it will break the >>>>> ACPI unbind logic and cause following warning messages: >>>>> [ 185.026073] usb usb5: Oops, 'acpi_handle' corrupt >>>>> [ 185.035150] pci 0000:1b:00.0: Oops, 'acpi_handle' corrupt >>>>> [ 185.035515] pci 0000:18:02.0: Oops, 'acpi_handle' corrupt >>>>> [ 180.013656] port1: Oops, 'acpi_handle' corrupt >>>>> Please refer to https://bugzilla.kernel.org/attachment.cgi?id=104321 >>>>> for full log message. >>>> >>>> So my question is, did we have this problem before commit 3b63aaa70e1? >>>> >>>> If we did, then when did it start? Or was it present forever? >>>> >>>>> Above warning messages are caused by following scenario: >>>>> 1) acpi_dock_notifier_call() queues a task (T1) onto kacpi_hotplug_wq >>>>> 2) kacpi_hotplug_wq handles T1, which invokes acpi_dock_deferred_cb() >>>>> ->dock_notify()-> handle_eject_request()->hotplug_dock_devices() >>>>> 3) hotplug_dock_devices() first invokes registered hotplug callbacks to >>>>> destroy physical devices, then destroys all affected ACPI devices. >>>>> Everything seems perfect until now. But the acpiphp dock notification >>>>> handler will queue another task (T2) onto kacpi_hotplug_wq to really >>>>> destroy affected physical devices. >>>> >>>> Would not the solution be to modify it so that it didn't spawn the other >>>> task (T2), but removed the affected physical devices synchronously? >>>> >>>>> 4) kacpi_hotplug_wq finishes T1, and all affected ACPI devices have >>>>> been destroyed. >>>>> 5) kacpi_hotplug_wq handles T2, which destroys all affected physical >>>>> devices. >>>>> >>>>> So it breaks ACPI glue logic's expection because ACPI devices are destroyed >>>>> in step 3 and physical devices are destroyed in step 5. >>>>> >>>>> Signed-off-by: Jiang Liu <jiang.liu@xxxxxxxxxx> >>>>> Reported-by: Alexander E. Patrakov <patrakov@xxxxxxxxx> >>>>> Cc: Bjorn Helgaas <bhelgaas@xxxxxxxxxx> >>>>> Cc: Yinghai Lu <yinghai@xxxxxxxxxx> >>>>> Cc: "Rafael J. Wysocki" <rafael.j.wysocki@xxxxxxxxx> >>>>> Cc: linux-pci@xxxxxxxxxxxxxxx >>>>> Cc: linux-kernel@xxxxxxxxxxxxxxx >>>>> Cc: stable@xxxxxxxxxxxxxxx >>>>> --- >>>>> Hi Bjorn and Rafael, >>>>> The recursive lock changes haven't been tested yet, need help >>>>> from Alexander for testing. >>>> >>>> Well, let's just say I'm not a fan of recursive locks. Is that unavoidable >>>> here? >>> >>> What about the appended patch (on top of [1/9], untested)? >>> >>> Rafael >> It should have similar effect as patch 2/9, and it will encounter the >> same deadlock scenario as 2/9 too. > > And why exactly? > > I'm looking at acpiphp_disable_slot() and I'm not seeing where the > problematic lock is taken. Similarly for power_off_slot(). > > It should take the ACPI scan lock, but that's a different matter. > > Thanks, > Rafael The deadlock scenario is the same: hotplug_dock_devices() mutex_lock(&ds->hp_lock) dd->ops->handler() destroy pci bus unregister_hotplug_dock_device() mutex_lock(&ds->hp_lock) > > >>> --- >>> drivers/pci/hotplug/acpiphp_glue.c | 13 ++++++++++++- >>> 1 file changed, 12 insertions(+), 1 deletion(-) >>> >>> Index: linux-pm/drivers/pci/hotplug/acpiphp_glue.c >>> =================================================================== >>> --- linux-pm.orig/drivers/pci/hotplug/acpiphp_glue.c >>> +++ linux-pm/drivers/pci/hotplug/acpiphp_glue.c >>> @@ -145,9 +145,20 @@ static int post_dock_fixups(struct notif >>> return NOTIFY_OK; >>> } >>> >>> +static void handle_dock_event_func(acpi_handle handle, u32 event, void *context) >>> +{ >>> + if (event == ACPI_NOTIFY_EJECT_REQUEST) { >>> + struct acpiphp_func *func = context; >>> + >>> + if (!acpiphp_disable_slot(func->slot)) >>> + acpiphp_eject_slot(func->slot); >>> + } else { >>> + handle_hotplug_event_func(handle, event, context); >>> + } >>> +} >>> >>> static const struct acpi_dock_ops acpiphp_dock_ops = { >>> - .handler = handle_hotplug_event_func, >>> + .handler = handle_dock_event_func, >>> }; >>> >>> /* Check whether the PCI device is managed by native PCIe hotplug driver */ >>> >> -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
