From: Mauro Carvalho Chehab <mchehab@redhat.com>
Date: Tue, 23 Nov 2010 17:34:05 -0500
Subject: [edac] i7core_edac: fix PCI refcounting on reloads
Message-id: <20101123153405.6dafed54@pedra>
Patchwork-id: 29582
O-Subject: [PATCH RHEL5 27/29] BZ#:651869 i7core_edac: Avoid PCI refcount to
	reach zero on successive load/reload
Bugzilla: 651869
RH-Acked-by: Aristeu Rozanski <aris@redhat.com>

Changeset: a3e1541637f2096ab31af311c53eaeb0853650d3

That's a nasty bug that took me a lot of time to track, and whose
solution took just one line to solve. The best fragrances and the worse
poisons are shipped on the smalest bottles.

The drivers/pci/quick.c implements the pci_get_device function. The normal
behavior is that you call it, the function returns you a pdev pointer
and increment pdev->kobj.kref.refcount of the pci device. However,
if you want to keep searching an object, you need to pass the previous
pdev function to the search.

When you use a not null pointer to pdev "from" field, pci_get_device
will decrement pdev->kobj.kref.refcount, assuming that the driver won't
be using the previous pdev.

The solution is simple: we just need to call pci_dev_get() manually,
for the pdev's that the driver will actually use.

Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
Signed-off-by: Jarod Wilson <jarod@redhat.com>

diff --git a/drivers/edac/i7core_edac.c b/drivers/edac/i7core_edac.c
index b69c51f..9561551 100644
--- a/drivers/edac/i7core_edac.c
+++ b/drivers/edac/i7core_edac.c
@@ -1396,6 +1396,13 @@ static int i7core_get_onedevice(struct pci_dev **prev,
 		dev_descr->func,
 		PCI_VENDOR_ID_INTEL, dev_descr->dev_id);
 
+	/*
+	 * As stated on drivers/pci/search.c, the reference count for
+	 * @from is always decremented if it is not %NULL. So, as we need
+	 * to get all devices up to null, we need to do a get for the device
+	 */
+	pci_dev_get(pdev);
+
 	*prev = pdev;
 
 	return 0;