PCI: Allow pci_resize_resource() for devices on root bus

When resizing a BAR, pci_reassign_bridge_resources() is invoked to bring
the bridge windows of parent bridges in line with the new BAR assignment.

This assumes the device whose BAR is being resized lives on a subordinate
bus, but this is not necessarily the case. A device may live on the root
bus, in which case dev->bus->self is NULL, and passing a NULL pci_dev
pointer to pci_reassign_bridge_resources() will cause it to crash.

So let's make the call to pci_reassign_bridge_resources() conditional on
whether dev->bus->self is non-NULL in the first place.

Fixes: 8bb705e3e79d84e7 ("PCI: Add pci_resize_resource() for resizing BARs")
Link: https://lore.kernel.org/r/20200421162256.26887-1-ardb@kernel.org
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Christian König <christian.koenig@amd.com>

diff --git a/drivers/pci/setup-res.c b/drivers/pci/setup-res.c
index d8ca40a..d21fa04 100644 (file)
--- a/drivers/pci/setup-res.c
+++ b/drivers/pci/setup-res.c
@@ -439,10 +439,11 @@ int pci_resize_resource(struct pci_dev *dev, int resno, int size)
        res->end = res->start + pci_rebar_size_to_bytes(size) - 1;
 
        /* Check if the new config works by trying to assign everything. */
-       ret = pci_reassign_bridge_resources(dev->bus->self, res->flags);
-       if (ret)
-               goto error_resize;
-
+       if (dev->bus->self) {
+               ret = pci_reassign_bridge_resources(dev->bus->self, res->flags);
+               if (ret)
+                       goto error_resize;
+       }
        return 0;
 
 error_resize: