PCI/ACPI: Protect acpi_pci_drivers list with mutex

Use mutex to protect global acpi_pci_drivers list against PCI
host bridge hotplug operations.

Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Taku Izumi <izumi.taku@jp.fujitsu.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

1 files changed, 19 insertions, 17 deletions

diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
index 4bec13d9c2bf..d710585e4a7f 100644
--- a/drivers/acpi/pci_root.c
+++ b/drivers/acpi/pci_root.c
@@ -27,7 +27,7 @@
 #include <linux/module.h>
 #include <linux/init.h>
 #include <linux/types.h>
-#include <linux/spinlock.h>
+#include <linux/mutex.h>
 #include <linux/pm.h>
 #include <linux/pm_runtime.h>
 #include <linux/pci.h>
@@ -71,6 +71,8 @@ static struct acpi_driver acpi_pci_root_driver = {
                 },
 };
 
+/* Lock to protect both acpi_pci_roots and acpi_pci_drivers lists */
+static DEFINE_MUTEX(acpi_pci_root_lock);
 static LIST_HEAD(acpi_pci_roots);
 static LIST_HEAD(acpi_pci_drivers);
 
@@ -81,34 +83,30 @@ int acpi_pci_register_driver(struct acpi_pci_driver *driver)
         int n = 0;
         struct acpi_pci_root *root;
 
+        mutex_lock(&acpi_pci_root_lock);
         list_add_tail(&driver->node, &acpi_pci_drivers);
-
-        if (!driver->add)
-                return 0;
-
-        list_for_each_entry(root, &acpi_pci_roots, node) {
-                driver->add(root->device->handle);
-                n++;
-        }
+        if (driver->add)
+                list_for_each_entry(root, &acpi_pci_roots, node) {
+                        driver->add(root->device->handle);
+                        n++;
+                }
+        mutex_unlock(&acpi_pci_root_lock);
 
         return n;
 }
-
 EXPORT_SYMBOL(acpi_pci_register_driver);
 
 void acpi_pci_unregister_driver(struct acpi_pci_driver *driver)
 {
         struct acpi_pci_root *root;
 
+        mutex_lock(&acpi_pci_root_lock);
         list_del(&driver->node);
-
-        if (!driver->remove)
-                return;
-
-        list_for_each_entry(root, &acpi_pci_roots, node)
-                driver->remove(root->device->handle);
+        if (driver->remove)
+                list_for_each_entry(root, &acpi_pci_roots, node)
+                        driver->remove(root->device->handle);
+        mutex_unlock(&acpi_pci_root_lock);
 }
-
 EXPORT_SYMBOL(acpi_pci_unregister_driver);
 
 acpi_handle acpi_get_pci_rootbridge_handle(unsigned int seg, unsigned int bus)
@@ -628,9 +626,11 @@ static int acpi_pci_root_start(struct acpi_device *device)
         struct acpi_pci_root *root = acpi_driver_data(device);
         struct acpi_pci_driver *driver;
 
+        mutex_lock(&acpi_pci_root_lock);
         list_for_each_entry(driver, &acpi_pci_drivers, node)
                 if (driver->add)
                         driver->add(device->handle);
+        mutex_unlock(&acpi_pci_root_lock);
 
         pci_bus_add_devices(root->bus);
 
@@ -642,9 +642,11 @@ static int acpi_pci_root_remove(struct acpi_device *device, int type)
         struct acpi_pci_root *root = acpi_driver_data(device);
         struct acpi_pci_driver *driver;
 
+        mutex_lock(&acpi_pci_root_lock);
         list_for_each_entry(driver, &acpi_pci_drivers, node)
                 if (driver->remove)
                         driver->remove(root->device->handle);
+        mutex_unlock(&acpi_pci_root_lock);
 
         device_set_run_wake(root->bus->bridge, false);
         pci_acpi_remove_bus_pm_notifier(device);