linux-kernel - Re: [3.11.4] Thunderbolt/PCI unplug oops in pci_pme_list

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Date:	Wed, 16 Oct 2013 14:21:23 -0600
From:	Bjorn Helgaas <bhelgaas@...gle.com>
To:	Matthew Garrett <mjg59@...f.ucam.org>
Cc:	Andreas Noever <andreas.noever@...il.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"Rafael J. Wysocki" <rjw@...k.pl>,
	"linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
	Mika Westerberg <mika.westerberg@...ux.intel.com>,
	"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
Subject: Re: [3.11.4] Thunderbolt/PCI unplug oops in pci_pme_list_scan

On Tue, Oct 15, 2013 at 03:44:52AM +0100, Matthew Garrett wrote:
> On Mon, Oct 14, 2013 at 05:50:38PM -0600, Bjorn Helgaas wrote:
> > [+cc Rafael, Mika, Kirill, linux-pci]
> > 
> > On Mon, Oct 14, 2013 at 4:47 PM, Andreas Noever
> > <andreas.noever@...il.com> wrote:
> > > When I unplug the Thunderbolt ethernet adapter on my MacBookPro Linux
> > > crashes a few seconds later. Using
> > > echo 1 > /sys/bus/pci/devices/0000:08:00.0/remove
> > > to remove a bridge two levels above the device triggers the fault immediately:
> > 
> > There have been significant changes in acpiphp related to Thunderbolt
> > since v3.11.
> 
> Apple don't expose Thunderbolt via ACPI, so it appears as native PCIe. 
> I'd be surprised if acpiphp makes a difference here.

Yeah, you're right; I wasn't paying attention.

We save a pci_dev pointer in the pci_pme_list, which of course has a
longer lifetime than the pci_dev itself, but we don't acquire a reference
on it, so I suspect the pci_dev got released before we got around to
doing the pci_pme_list_scan().

Andreas, can you try the patch below?  It's against v3.12-rc2, but it
should apply to v3.11, too.

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index ad7fc72..8b0a2f3 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -1580,6 +1580,7 @@ static void pci_pme_list_scan(struct work_struct *work)
 				pci_pme_wakeup(pme_dev->dev, NULL);
 			} else {
 				list_del(&pme_dev->list);
+				pci_dev_put(pme_dev->dev);
 				kfree(pme_dev);
 			}
 		}
@@ -1640,7 +1641,7 @@ void pci_pme_active(struct pci_dev *dev, bool enable)
 					  GFP_KERNEL);
 			if (!pme_dev)
 				goto out;
-			pme_dev->dev = dev;
+			pme_dev->dev = pci_dev_get(dev);
 			mutex_lock(&pci_pme_list_mutex);
 			list_add(&pme_dev->list, &pci_pme_list);
 			if (list_is_singular(&pci_pme_list))
@@ -1652,6 +1653,7 @@ void pci_pme_active(struct pci_dev *dev, bool enable)
 			list_for_each_entry(pme_dev, &pci_pme_list, list) {
 				if (pme_dev->dev == dev) {
 					list_del(&pme_dev->list);
+					pci_dev_put(pme_dev->dev);
 					kfree(pme_dev);
 					break;
 				}
--
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