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-rw-r--r--drivers/acpi/video.c41
1 files changed, 35 insertions, 6 deletions
diff --git a/drivers/acpi/video.c b/drivers/acpi/video.c
index 1bdfb37377e3..a63566ba230b 100644
--- a/drivers/acpi/video.c
+++ b/drivers/acpi/video.c
@@ -76,6 +76,7 @@ MODULE_LICENSE("GPL");
static int brightness_switch_enabled = 1;
module_param(brightness_switch_enabled, bool, 0644);
+static int register_count = 0;
static int acpi_video_bus_add(struct acpi_device *device);
static int acpi_video_bus_remove(struct acpi_device *device, int type);
static int acpi_video_resume(struct acpi_device *device);
@@ -2318,6 +2319,13 @@ static int __init intel_opregion_present(void)
int acpi_video_register(void)
{
int result = 0;
+ if (register_count) {
+ /*
+ * if the function of acpi_video_register is already called,
+ * don't register the acpi_vide_bus again and return no error.
+ */
+ return 0;
+ }
acpi_video_dir = proc_mkdir(ACPI_VIDEO_CLASS, acpi_root_dir);
if (!acpi_video_dir)
@@ -2329,10 +2337,35 @@ int acpi_video_register(void)
return -ENODEV;
}
+ /*
+ * When the acpi_video_bus is loaded successfully, increase
+ * the counter reference.
+ */
+ register_count = 1;
+
return 0;
}
EXPORT_SYMBOL(acpi_video_register);
+void acpi_video_unregister(void)
+{
+ if (!register_count) {
+ /*
+ * If the acpi video bus is already unloaded, don't
+ * unload it again and return directly.
+ */
+ return;
+ }
+ acpi_bus_unregister_driver(&acpi_video_bus);
+
+ remove_proc_entry(ACPI_VIDEO_CLASS, acpi_root_dir);
+
+ register_count = 0;
+
+ return;
+}
+EXPORT_SYMBOL(acpi_video_unregister);
+
/*
* This is kind of nasty. Hardware using Intel chipsets may require
* the video opregion code to be run first in order to initialise
@@ -2350,16 +2383,12 @@ static int __init acpi_video_init(void)
return acpi_video_register();
}
-void acpi_video_exit(void)
+static void __exit acpi_video_exit(void)
{
-
- acpi_bus_unregister_driver(&acpi_video_bus);
-
- remove_proc_entry(ACPI_VIDEO_CLASS, acpi_root_dir);
+ acpi_video_unregister();
return;
}
-EXPORT_SYMBOL(acpi_video_exit);
module_init(acpi_video_init);
module_exit(acpi_video_exit);