linux-kernel - Re: [BUGFIX 2/9] ACPIPHP: fix device destroying order issue when handling dock notification

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Date:	Fri, 14 Jun 2013 14:23:34 +0200
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Jiang Liu <jiang.liu@...wei.com>
Cc:	Bjorn Helgaas <bhelgaas@...gle.com>,
	Yinghai Lu <yinghai@...nel.org>,
	"Alexander E . Patrakov" <patrakov@...il.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Yijing Wang <wangyijing@...wei.com>,
	Jiang Liu <liuj97@...il.com>, linux-pci@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	"Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
	stable@...r.kernel.org
Subject: Re: [BUGFIX 2/9] ACPIPHP: fix device destroying order issue when handling dock notification

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@...wei.com>
> > Reported-by: Alexander E. Patrakov <patrakov@...il.com>
> > Cc: Bjorn Helgaas <bhelgaas@...gle.com>
> > Cc: Yinghai Lu <yinghai@...nel.org>
> > Cc: "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>
> > Cc: linux-pci@...r.kernel.org
> > Cc: linux-kernel@...r.kernel.org
> > Cc: stable@...r.kernel.org
> > ---
> > 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


---
 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 */

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