From dc4fdaf0e4839109169d8261814813816951c75f Mon Sep 17 00:00:00 2001 From: "Rafael J. Wysocki" Date: Thu, 28 May 2015 01:39:53 +0200 Subject: [PATCH] PCI / ACPI: Do not set ACPI companions for host bridges with parents Commit 97badf873ab6 (device property: Make it possible to use secondary firmware nodes) uncovered a bug in the x86 (and ia64) PCI host bridge initialization code that assumes bridge->bus->sysdata to always point to a struct pci_sysdata object which need not be the case (in particular, the Xen PCI frontend driver sets it to point to a different data type). If it is not the case, an incorrect pointer (or a piece of data that is not a pointer at all) will be passed to ACPI_COMPANION_SET() and that may cause interesting breakage to happen going forward. To work around this problem use the observation that the ACPI host bridge initialization always passes NULL as parent to pci_create_root_bus(), so if pcibios_root_bridge_prepare() sees a non-NULL parent of the bridge, it should not attempt to set an ACPI companion for it, because that means that pci_create_root_bus() has been called by someone else. Fixes: 97badf873ab6 (device property: Make it possible to use secondary firmware nodes) Reported-and-tested-by: Sander Eikelenboom Signed-off-by: Rafael J. Wysocki Acked-by: Bjorn Helgaas --- Reading git-format-patch failed