commit ac245f57c5837207208a0cee9f56b299666b52f2
Author: Matthew Wilcox <matthew@wil.cx>
Date:   Mon Oct 20 19:13:08 2008 -0600

    PCI: Fix reference counting bug
    
    pci_get_subsys() will decrement the reference count of the device that
    it starts searching from.  Unfortunately, the pci_find_device() interface
    will already have decremented the reference count of the device earlier,
    so the device will end up losing all reference counts and be freed.
    
    We can fix this by incrementing the reference count of the device to
    start searching from before calling pci_get_subsys().
    
    Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
    Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

diff --git a/drivers/pci/search.c b/drivers/pci/search.c
index 4edfc47..5af8bd5 100644
--- a/drivers/pci/search.c
+++ b/drivers/pci/search.c
@@ -166,6 +166,7 @@ struct pci_dev *pci_find_device(unsigned int vendor, unsigned int device,
 {
 	struct pci_dev *pdev;
 
+	pci_dev_get(from);
 	pdev = pci_get_subsys(vendor, device, PCI_ANY_ID, PCI_ANY_ID, from);
 	pci_dev_put(pdev);
 	return pdev;
@@ -270,12 +271,8 @@ static struct pci_dev *pci_get_dev_by_id(const struct pci_device_id *id,
 	struct pci_dev *pdev = NULL;
 
 	WARN_ON(in_interrupt());
-	if (from) {
-		/* FIXME
-		 * take the cast off, when bus_find_device is made const.
-		 */
-		dev_start = (struct device *)&from->dev;
-	}
+	if (from)
+		dev_start = &from->dev;
 	dev = bus_find_device(&pci_bus_type, dev_start, (void *)id,
 			      match_pci_dev_by_id);
 	if (dev)