PCI: Assign resources before drivers claim devices (pci_scan_root_bus())

Previously, pci_scan_root_bus() created a root PCI bus, enumerated the
devices on it, and called pci_bus_add_devices(), which made the devices
available for drivers to claim them.

Most callers assigned resources to devices after pci_scan_root_bus()
returns, which may be after drivers have claimed the devices.  This is
incorrect; the PCI core should not change device resources while a driver
is managing the device.

Remove pci_bus_add_devices() from pci_scan_root_bus() and do it after any
resource assignment in the callers.

Note that ARM's pci_common_init_dev() already called pci_bus_add_devices()
after pci_scan_root_bus(), so we only need to remove the first call:

  pci_common_init_dev
    pcibios_init_hw
      pci_scan_root_bus
        pci_bus_add_devices        # first call
    pci_bus_assign_resources
    pci_bus_add_devices            # second call

[bhelgaas: changelog, drop "root_bus" var in alpha common_init_pci(),
return failure earlier in mn10300, add "return" in x86 pcibios_scan_root(),
return early if xtensa platform_pcibios_fixup() fails]
Signed-off-by: Yijing Wang <[email protected]>
Signed-off-by: Bjorn Helgaas <[email protected]>
CC: Richard Henderson <[email protected]>
CC: Ivan Kokshaysky <[email protected]>
CC: Matt Turner <[email protected]>
CC: David Howells <[email protected]>
CC: Tony Luck <[email protected]>
CC: Michal Simek <[email protected]>
CC: Ralf Baechle <[email protected]>
CC: Koichi Yasutake <[email protected]>
CC: Sebastian Ott <[email protected]>
CC: "David S. Miller" <[email protected]>
CC: Chris Metcalf <[email protected]>
CC: Chris Zankel <[email protected]>
CC: Max Filippov <[email protected]>
CC: Thomas Gleixner <[email protected]>

2 files changed, 4 insertions, 0 deletions

diff --git a/arch/tile/kernel/pci.c b/arch/tile/kernel/pci.c
index 325df47f114d..9475a74cd53a 100644
--- a/arch/tile/kernel/pci.c
+++ b/arch/tile/kernel/pci.c
@@ -339,6 +339,8 @@ int __init pcibios_init(void)
 			struct pci_bus *next_bus;
 			struct pci_dev *dev;
 
+			pci_bus_add_devices(root_bus);
+
 			list_for_each_entry(dev, &root_bus->devices, bus_list) {
 				/*
 				 * Find the PCI host controller, ie. the 1st
diff --git a/arch/tile/kernel/pci_gx.c b/arch/tile/kernel/pci_gx.c
index 2c95f37ebbed..b1df847d0686 100644
--- a/arch/tile/kernel/pci_gx.c
+++ b/arch/tile/kernel/pci_gx.c
@@ -1030,6 +1030,8 @@ int __init pcibios_init(void)
 alloc_mem_map_failed:
 			break;
 		}
+
+		pci_bus_add_devices(root_bus);
 	}
 
 	return 0;