[RFC PATCH v1 19/22] PCI/x86: enable PCI bus lock mechanism for x86 platforms

[Jiang Liu <liuj97@gmail.com>]

This patch turns on PCI bus lock mechanism for x86 platforms. It also
enhances x86 specific PCI implementation to support PCI bus lock.

Signed-off-by: Jiang Liu <liuj97@gmail.com>
---
 arch/x86/pci/acpi.c   |    6 +++++-
 arch/x86/pci/common.c |   12 ++++++++++++
 drivers/pci/Kconfig   |    3 +--
 3 files changed, 18 insertions(+), 3 deletions(-)

diff --git a/arch/x86/pci/acpi.c b/arch/x86/pci/acpi.c
index 2bb885a..c68dbdf 100644
--- a/arch/x86/pci/acpi.c
+++ b/arch/x86/pci/acpi.c
@@ -414,7 +414,8 @@ struct pci_bus * __devinit pci_acpi_scan_root(struct acpi_pci_root *root)
 	 * Maybe the desired pci bus has been already scanned. In such case
 	 * it is unnecessary to scan the pci bus with the given domain,busnum.
 	 */
-	bus = pci_find_bus(domain, busnum);
+	bus = __pci_get_and_lock_bus(domain, busnum,
+				     PCI_BUS_STATE_STOPPING - 1);
 	if (bus) {
 		/*
 		 * If the desired bus exits, the content of bus->sysdata will
@@ -449,6 +450,7 @@ struct pci_bus * __devinit pci_acpi_scan_root(struct acpi_pci_root *root)
 			pci_free_resource_list(&resources);
 			__release_pci_root_info(info);
 		}
+		pci_bus_get(bus);
 	}
 
 	/* After the PCI-E bus has been walked and all devices discovered,
@@ -475,6 +477,8 @@ struct pci_bus * __devinit pci_acpi_scan_root(struct acpi_pci_root *root)
 #endif
 	}
 
+	pci_unlock_and_put_bus(bus);
+
 	return bus;
 }
 
diff --git a/arch/x86/pci/common.c b/arch/x86/pci/common.c
index 0ad990a..8b7ae63 100644
--- a/arch/x86/pci/common.c
+++ b/arch/x86/pci/common.c
@@ -667,6 +667,18 @@ struct pci_bus * __devinit pci_scan_bus_with_sysdata(int busno)
 	return pci_scan_bus_on_node(busno, &pci_root_ops, -1);
 }
 
+static DEFINE_MUTEX(pci_root_bus_mutex);
+
+void arch_pci_lock_host_bridge_hotplug(void)
+{
+	mutex_lock(&pci_root_bus_mutex);
+}
+
+void arch_pci_unlock_host_bridge_hotplug(void)
+{
+	mutex_unlock(&pci_root_bus_mutex);
+}
+
 /*
  * NUMA info for PCI busses
  *
diff --git a/drivers/pci/Kconfig b/drivers/pci/Kconfig
index a6df8b1..1bbe924 100644
--- a/drivers/pci/Kconfig
+++ b/drivers/pci/Kconfig
@@ -122,5 +122,4 @@ config PCI_LABEL
 	select NLS
 
 config PCI_BUS_LOCK
-	bool
-	default n
+	def_bool y if X86
-- 
1.7.9.5