[PATCH] pci: Don't crash when reading mpss from root complex

[Benjamin Herrenschmidt]

In pcie_find_smpss(), we have the following statement:

 	if (dev->is_hotplug_bridge && (!list_is_singular(&dev->bus->devices) ||
	    dev->bus->self->pcie_type != PCI_EXP_TYPE_ROOT_PORT))

The problem is that at least on my machine, this gets called for the
root complex (virtual P2P bridge), and dev->bus->self is NULL since
the parent bus for this is not itself anchor to a PCI device.

This adds the necessary NULL check.

Signed-off-by: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/pci/probe.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 8473727..09d1c0f 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -1351,7 +1351,8 @@ static int pcie_find_smpss(struct pci_dev *dev, void *data)
 	 * will occur as normal.
 	 */
 	if (dev->is_hotplug_bridge && (!list_is_singular(&dev->bus->devices) ||
-	    dev->bus->self->pcie_type != PCI_EXP_TYPE_ROOT_PORT))
+	     (dev->bus->self &&
+	      dev->bus->self->pcie_type != PCI_EXP_TYPE_ROOT_PORT)))
 		*smpss = 0;
 
 	if (*smpss > dev->pcie_mpss)
-- 
1.7.4.1






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