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ACPI / video: driver must be registered before checking for keypresses
acpi_video_handles_brightness_key_presses() may use an uninitialized mutex. The error has been reported by lockdep: DEBUG_LOCKS_WARN_ON(l->magic != l). The function assumes that the video driver has been registered before being called. As explained in the comment of acpi_video_init(), the registration of the video class may be defered and thus may not take place in the init function of the module. Use completion mechanisms to make sure that acpi_video_handles_brightness_key_presses() wait for the completion of acpi_video_register() before using the mutex. Also get rid of register_count since task completion can replace it. Signed-off-by: Adrien Schildknecht <adrien+dev@schischi.me> Reviewed-by: Hans de Goede <hdegoede@redhat.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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49eb520822
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aecbd9b1bf
1 changed files with 14 additions and 13 deletions
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@ -90,8 +90,8 @@ module_param(device_id_scheme, bool, 0444);
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static bool only_lcd = false;
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static bool only_lcd = false;
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module_param(only_lcd, bool, 0444);
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module_param(only_lcd, bool, 0444);
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static int register_count;
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static DECLARE_COMPLETION(register_done);
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static DEFINE_MUTEX(register_count_mutex);
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static DEFINE_MUTEX(register_done_mutex);
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static struct mutex video_list_lock;
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static struct mutex video_list_lock;
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static struct list_head video_bus_head;
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static struct list_head video_bus_head;
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static int acpi_video_bus_add(struct acpi_device *device);
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static int acpi_video_bus_add(struct acpi_device *device);
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@ -2049,8 +2049,8 @@ int acpi_video_register(void)
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{
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{
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int ret = 0;
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int ret = 0;
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mutex_lock(®ister_count_mutex);
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mutex_lock(®ister_done_mutex);
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if (register_count) {
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if (completion_done(®ister_done)) {
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/*
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/*
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* if the function of acpi_video_register is already called,
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* if the function of acpi_video_register is already called,
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* don't register the acpi_vide_bus again and return no error.
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* don't register the acpi_vide_bus again and return no error.
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@ -2071,22 +2071,22 @@ int acpi_video_register(void)
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* When the acpi_video_bus is loaded successfully, increase
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* When the acpi_video_bus is loaded successfully, increase
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* the counter reference.
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* the counter reference.
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*/
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*/
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register_count = 1;
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complete(®ister_done);
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leave:
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leave:
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mutex_unlock(®ister_count_mutex);
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mutex_unlock(®ister_done_mutex);
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return ret;
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return ret;
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}
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}
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EXPORT_SYMBOL(acpi_video_register);
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EXPORT_SYMBOL(acpi_video_register);
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void acpi_video_unregister(void)
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void acpi_video_unregister(void)
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{
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{
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mutex_lock(®ister_count_mutex);
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mutex_lock(®ister_done_mutex);
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if (register_count) {
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if (completion_done(®ister_done)) {
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acpi_bus_unregister_driver(&acpi_video_bus);
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acpi_bus_unregister_driver(&acpi_video_bus);
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register_count = 0;
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reinit_completion(®ister_done);
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}
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}
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mutex_unlock(®ister_count_mutex);
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mutex_unlock(®ister_done_mutex);
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}
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}
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EXPORT_SYMBOL(acpi_video_unregister);
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EXPORT_SYMBOL(acpi_video_unregister);
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@ -2094,20 +2094,21 @@ void acpi_video_unregister_backlight(void)
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{
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{
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struct acpi_video_bus *video;
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struct acpi_video_bus *video;
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mutex_lock(®ister_count_mutex);
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mutex_lock(®ister_done_mutex);
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if (register_count) {
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if (completion_done(®ister_done)) {
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mutex_lock(&video_list_lock);
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mutex_lock(&video_list_lock);
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list_for_each_entry(video, &video_bus_head, entry)
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list_for_each_entry(video, &video_bus_head, entry)
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acpi_video_bus_unregister_backlight(video);
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acpi_video_bus_unregister_backlight(video);
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mutex_unlock(&video_list_lock);
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mutex_unlock(&video_list_lock);
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}
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}
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mutex_unlock(®ister_count_mutex);
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mutex_unlock(®ister_done_mutex);
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}
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}
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bool acpi_video_handles_brightness_key_presses(void)
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bool acpi_video_handles_brightness_key_presses(void)
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{
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{
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bool have_video_busses;
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bool have_video_busses;
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wait_for_completion(®ister_done);
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mutex_lock(&video_list_lock);
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mutex_lock(&video_list_lock);
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have_video_busses = !list_empty(&video_bus_head);
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have_video_busses = !list_empty(&video_bus_head);
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mutex_unlock(&video_list_lock);
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mutex_unlock(&video_list_lock);
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