diff options
| -rw-r--r-- | drivers/acpi/acpi_video.c | 43 |
1 files changed, 21 insertions, 22 deletions
diff --git a/drivers/acpi/acpi_video.c b/drivers/acpi/acpi_video.c index efa0ab553aa3..5b877a127167 100644 --- a/drivers/acpi/acpi_video.c +++ b/drivers/acpi/acpi_video.c @@ -82,6 +82,7 @@ static int disable_backlight_sysfs_if = -1; module_param(disable_backlight_sysfs_if, int, 0444); static int register_count; +static DEFINE_MUTEX(register_count_mutex); static struct mutex video_list_lock; static struct list_head video_bus_head; static int acpi_video_bus_add(struct acpi_device *device); @@ -1964,14 +1965,15 @@ static int __init intel_opregion_present(void) int acpi_video_register(void) { - int ret; + int ret = 0; + mutex_lock(®ister_count_mutex); 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; + goto leave; } mutex_init(&video_list_lock); @@ -1981,7 +1983,7 @@ int acpi_video_register(void) ret = acpi_bus_register_driver(&acpi_video_bus); if (ret) - return ret; + goto leave; /* * When the acpi_video_bus is loaded successfully, increase @@ -1989,24 +1991,20 @@ int acpi_video_register(void) */ register_count = 1; - return 0; +leave: + mutex_unlock(®ister_count_mutex); + return ret; } 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; + mutex_lock(®ister_count_mutex); + if (register_count) { + acpi_bus_unregister_driver(&acpi_video_bus); + register_count = 0; } - acpi_bus_unregister_driver(&acpi_video_bus); - - register_count = 0; - - return; + mutex_unlock(®ister_count_mutex); } EXPORT_SYMBOL(acpi_video_unregister); @@ -2014,13 +2012,14 @@ void acpi_video_unregister_backlight(void) { struct acpi_video_bus *video; - if (!register_count) - return; - - mutex_lock(&video_list_lock); - list_for_each_entry(video, &video_bus_head, entry) - acpi_video_bus_unregister_backlight(video); - mutex_unlock(&video_list_lock); + mutex_lock(®ister_count_mutex); + if (register_count) { + mutex_lock(&video_list_lock); + list_for_each_entry(video, &video_bus_head, entry) + acpi_video_bus_unregister_backlight(video); + mutex_unlock(&video_list_lock); + } + mutex_unlock(®ister_count_mutex); } EXPORT_SYMBOL(acpi_video_unregister_backlight); |