ACPI: convert acpi_device_lock spinlock to mutex

Convert acpi_device_lock to a mutex to avoid
a potential race upon access to /proc/acpi/wakeup

Delete the lock entirely in wakeup.c
since it is not necessary (and can not sleep)

Found-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>

1 files changed, 7 insertions, 7 deletions

diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
index 20c23c049207..e63f2febad84 100644
--- a/drivers/acpi/scan.c
+++ b/drivers/acpi/scan.c
@@ -24,7 +24,7 @@ extern struct acpi_device *acpi_root;
 
 static LIST_HEAD(acpi_device_list);
 static LIST_HEAD(acpi_bus_id_list);
-DEFINE_SPINLOCK(acpi_device_lock);
+DEFINE_MUTEX(acpi_device_lock);
 LIST_HEAD(acpi_wakeup_device_list);
 
 struct acpi_device_bus_id{
@@ -500,7 +500,7 @@ static int acpi_device_register(struct acpi_device *device,
                 return -ENOMEM;
         }
 
-        spin_lock(&acpi_device_lock);
+        mutex_lock(&acpi_device_lock);
         /*
          * Find suitable bus_id and instance number in acpi_bus_id_list
          * If failed, create one and link it into acpi_bus_id_list
@@ -528,7 +528,7 @@ static int acpi_device_register(struct acpi_device *device,
                 list_add_tail(&device->g_list, &acpi_device_list);
         if (device->wakeup.flags.valid)
                 list_add_tail(&device->wakeup_list, &acpi_wakeup_device_list);
-        spin_unlock(&acpi_device_lock);
+        mutex_unlock(&acpi_device_lock);
 
         if (device->parent)
                 device->dev.parent = &parent->dev;
@@ -549,20 +549,20 @@ static int acpi_device_register(struct acpi_device *device,
         device->removal_type = ACPI_BUS_REMOVAL_NORMAL;
         return 0;
   end:
-        spin_lock(&acpi_device_lock);
+        mutex_lock(&acpi_device_lock);
         if (device->parent) {
                 list_del(&device->node);
                 list_del(&device->g_list);
         } else
                 list_del(&device->g_list);
         list_del(&device->wakeup_list);
-        spin_unlock(&acpi_device_lock);
+        mutex_unlock(&acpi_device_lock);
         return result;
 }
 
 static void acpi_device_unregister(struct acpi_device *device, int type)
 {
-        spin_lock(&acpi_device_lock);
+        mutex_lock(&acpi_device_lock);
         if (device->parent) {
                 list_del(&device->node);
                 list_del(&device->g_list);
@@ -570,7 +570,7 @@ static void acpi_device_unregister(struct acpi_device *device, int type)
                 list_del(&device->g_list);
 
         list_del(&device->wakeup_list);
-        spin_unlock(&acpi_device_lock);
+        mutex_unlock(&acpi_device_lock);
 
         acpi_detach_data(device->handle, acpi_bus_data_handler);