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PCI / ACPI fix for v4.1-rc6 

This fixes a bug uncovered by a recent driver core change that
 modified the implementation of the ACPI_COMPANION_SET() macro to
 strictly rely on its second argument to be either NULL or a valid
 pointer to struct acpi_device.
 
 As it turns out, pcibios_root_bridge_prepare() on x86 and ia64
 works with the assumption that the only code path calling
 pci_create_root_bus() is pci_acpi_scan_root() and therefore
 the sysdata argument passed to it will always match the
 expectations of pcibios_root_bridge_prepare().  That need not
 be the case, however, and in particular it is not the case for
 the Xen pcifront driver that passes a pointer to its own private
 data strcture as sysdata to pci_scan_bus_parented() which then
 passes it to pci_create_root_bus() and it ends up being used
 incorrectly by pcibios_root_bridge_prepare().
 
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Merge tag 'acpi-pci-4.1-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm

Pull PCI / ACPI fix from Rafael Wysocki:
 "This fixes a bug uncovered by a recent driver core change that
  modified the implementation of the ACPI_COMPANION_SET() macro to
  strictly rely on its second argument to be either NULL or a valid
  pointer to struct acpi_device.

  As it turns out, pcibios_root_bridge_prepare() on x86 and ia64 works
  with the assumption that the only code path calling pci_create_root_bus()
  is pci_acpi_scan_root() and therefore the sysdata argument passed to
  it will always match the expectations of pcibios_root_bridge_prepare().

  That need not be the case, however, and in particular it is not the
  case for the Xen pcifront driver that passes a pointer to its own
  private data strcture as sysdata to pci_scan_bus_parented() which then
  passes it to pci_create_root_bus() and it ends up being used incorrectly
  by pcibios_root_bridge_prepare()"

* tag 'acpi-pci-4.1-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
  PCI / ACPI: Do not set ACPI companions for host bridges with parents
This commit is contained in:
Linus Torvalds 2015-05-29 17:09:39 -07:00
parent 1be44e234b dc4fdaf0e4
commit aaa20fc233
2 changed files with 20 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

13
arch/ia64/pci/pci.c
View File

@ -478,9 +478,16 @@ struct pci_bus *pci_acpi_scan_root(struct acpi_pci_root *root)
int pcibios_root_bridge_prepare(struct pci_host_bridge *bridge) int pcibios_root_bridge_prepare(struct pci_host_bridge *bridge)
{ {
struct pci_controller *controller = bridge->bus->sysdata; /*
* We pass NULL as parent to pci_create_root_bus(), so if it is not NULL
ACPI_COMPANION_SET(&bridge->dev, controller->companion); * here, pci_create_root_bus() has been called by someone else and
* sysdata is likely to be different from what we expect. Let it go in
* that case.
*/
if (!bridge->dev.parent) {
struct pci_controller *controller = bridge->bus->sysdata;
ACPI_COMPANION_SET(&bridge->dev, controller->companion);
}
return 0; return 0;
} }

13
arch/x86/pci/acpi.c
View File

@ -482,9 +482,16 @@ struct pci_bus *pci_acpi_scan_root(struct acpi_pci_root *root)
int pcibios_root_bridge_prepare(struct pci_host_bridge *bridge) int pcibios_root_bridge_prepare(struct pci_host_bridge *bridge)
{ {
struct pci_sysdata *sd = bridge->bus->sysdata; /*
* We pass NULL as parent to pci_create_root_bus(), so if it is not NULL
ACPI_COMPANION_SET(&bridge->dev, sd->companion); * here, pci_create_root_bus() has been called by someone else and
* sysdata is likely to be different from what we expect. Let it go in
* that case.
*/
if (!bridge->dev.parent) {
struct pci_sysdata *sd = bridge->bus->sysdata;
ACPI_COMPANION_SET(&bridge->dev, sd->companion);
}
return 0; return 0;
} }