x86/ioapic: Ignore root bridges without a companion ACPI device

Some PCI root bridges don't have a corresponding ACPI device.
This can be the case on some old platforms. Don't call acpi_ioapic_add()
on these bridges because they can't support ioapic hotplug.

Reported-and-tested-by: Borislav Petkov <[email protected]>
Signed-off-by: Rui Wang <[email protected]>
Reviewed-by: Borislav Petkov <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>

diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c
index ec538d3d2bd5d82a928d0ee99082a581f180fbc6..f30ca75b5b6c7e20055e881776c44eaf50acbe0a 100644 (file)
--- a/drivers/pci/setup-bus.c
+++ b/drivers/pci/setup-bus.c
@@ -1855,7 +1855,10 @@ void __init pci_assign_unassigned_resources(void)
 
        list_for_each_entry(root_bus, &pci_root_buses, node) {
                pci_assign_unassigned_root_bus_resources(root_bus);
-               acpi_ioapic_add(ACPI_HANDLE(root_bus->bridge));
+
+               /* Make sure the root bridge has a companion ACPI device: */
+               if (ACPI_HANDLE(root_bus->bridge))
+                       acpi_ioapic_add(ACPI_HANDLE(root_bus->bridge));
        }
 }