Use PCI bus lock to protect concurrent PCI device hotplug operations.

Signed-off-by: Jiang Liu <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: "H. Peter Anvin" <[email protected]>
Cc: [email protected]
Cc: Len Brown <[email protected]>
Cc: "Rafael J. Wysocki" <[email protected]>
Cc: Yinghai Lu <[email protected]>
Cc: Feng Tang <[email protected]>
Cc: [email protected]
Cc: [email protected]
---
 arch/ia64/pci/pci.c     |  2 +-
 arch/x86/pci/acpi.c     |  3 ++-
 drivers/acpi/pci_root.c | 14 ++++++++------
 drivers/pci/Kconfig     |  2 +-
 4 files changed, 12 insertions(+), 9 deletions(-)

diff --git a/arch/ia64/pci/pci.c b/arch/ia64/pci/pci.c
index de1474f..6e91e87 100644
--- a/arch/ia64/pci/pci.c
+++ b/arch/ia64/pci/pci.c
@@ -384,7 +384,7 @@ struct pci_bus *pci_acpi_scan_root(struct acpi_pci_root 
*root)
        }
 
        pci_scan_child_bus(pbus);
-       return pbus;
+       return pci_bus_get(pbus);
 
 out3:
        kfree(controller->window);
diff --git a/arch/x86/pci/acpi.c b/arch/x86/pci/acpi.c
index b972f04..6dddc06 100644
--- a/arch/x86/pci/acpi.c
+++ b/arch/x86/pci/acpi.c
@@ -534,7 +534,7 @@ struct pci_bus *pci_acpi_scan_root(struct acpi_pci_root 
*root)
                 */
                memcpy(bus->sysdata, sd, sizeof(*sd));
                kfree(info);
-               pci_bus_put(bus);
+               BUG_ON(pci_bus_lock(bus, PCI_BUS_STATE_REMOVED - 1, true) < 0);
        } else {
                probe_pci_root_info(info, device, busnum, domain);
 
@@ -561,6 +561,7 @@ struct pci_bus *pci_acpi_scan_root(struct acpi_pci_root 
*root)
                        pci_set_host_bridge_release(
                                to_pci_host_bridge(bus->bridge),
                                release_pci_root_info, info);
+                       pci_bus_get(bus);
                } else {
                        pci_free_resource_list(&resources);
                        __release_pci_root_info(info);
diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
index 21dda5a..eb01cc7 100644
--- a/drivers/acpi/pci_root.c
+++ b/drivers/acpi/pci_root.c
@@ -535,6 +535,7 @@ static int acpi_pci_root_add(struct acpi_device *device,
        }
 
        pci_bus_add_devices(root->bus);
+       pci_bus_unlock(root->bus, true);
        return 1;
 
 end:
@@ -546,13 +547,14 @@ static void acpi_pci_root_remove(struct acpi_device 
*device)
 {
        struct acpi_pci_root *root = acpi_driver_data(device);
 
-       pci_stop_root_bus(root->bus);
-
-       device_set_run_wake(root->bus->bridge, false);
-       pci_acpi_remove_bus_pm_notifier(device);
-
-       pci_remove_root_bus(root->bus);
+       if (pci_bus_lock(root->bus, PCI_BUS_STATE_REMOVED - 1, true) == 0) {
+               pci_stop_root_bus(root->bus);
+               device_set_run_wake(root->bus->bridge, false);
+               pci_acpi_remove_bus_pm_notifier(device);
+               pci_remove_root_bus(root->bus);
+       }
 
+       pci_bus_put(root->bus);
        kfree(root);
 }
 
diff --git a/drivers/pci/Kconfig b/drivers/pci/Kconfig
index 92e69bd..5ae3504 100644
--- a/drivers/pci/Kconfig
+++ b/drivers/pci/Kconfig
@@ -121,4 +121,4 @@ config PCI_LABEL
        select NLS
 
 config PCI_BUS_LOCK
-       def_bool n
+       def_bool y if (X86 || IA64)
-- 
1.8.1.2

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