[04/38] pci: Dont crash when reading mpss from root complex

Greg KH
2011-10-11T17:03:32Z

From: Benjamin Herrenschmidt <benh@kernel.crashing.org>

commit 1a4b1a41b8a3d5256019854e851beed063b34344 upstream.

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@kernel.crashing.org>
Acked-by: Jon Mason <mason@myri.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
drivers/pci/probe.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -1352,7 +1352,8 @@ static int pcie_find_smpss(struct pci_de
* 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)