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authorAdrien Schildknecht <adrien+dev@schischi.me>2016-01-04 23:22:28 +0100
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2016-01-05 13:38:50 +0100
commitaecbd9b1bff6afbe349921b406b99d285b412820 (patch)
tree002e2aea096bdb9c1f335f37bfe2ff7c19547c37 /drivers/acpi
parent49eb5208220a9eef7529decbdefd95e4b94a928b (diff)
downloadop-kernel-dev-aecbd9b1bff6afbe349921b406b99d285b412820.zip
op-kernel-dev-aecbd9b1bff6afbe349921b406b99d285b412820.tar.gz
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>
Diffstat (limited to 'drivers/acpi')
-rw-r--r--drivers/acpi/acpi_video.c27
1 files changed, 14 insertions, 13 deletions
diff --git a/drivers/acpi/acpi_video.c b/drivers/acpi/acpi_video.c
index 80b13d4..06a006f 100644
--- a/drivers/acpi/acpi_video.c
+++ b/drivers/acpi/acpi_video.c
@@ -90,8 +90,8 @@ module_param(device_id_scheme, bool, 0444);
static bool only_lcd = false;
module_param(only_lcd, bool, 0444);
-static int register_count;
-static DEFINE_MUTEX(register_count_mutex);
+static DECLARE_COMPLETION(register_done);
+static DEFINE_MUTEX(register_done_mutex);
static struct mutex video_list_lock;
static struct list_head video_bus_head;
static int acpi_video_bus_add(struct acpi_device *device);
@@ -2049,8 +2049,8 @@ int acpi_video_register(void)
{
int ret = 0;
- mutex_lock(&register_count_mutex);
- if (register_count) {
+ mutex_lock(&register_done_mutex);
+ if (completion_done(&register_done)) {
/*
* if the function of acpi_video_register is already called,
* don't register the acpi_vide_bus again and return no error.
@@ -2071,22 +2071,22 @@ int acpi_video_register(void)
* When the acpi_video_bus is loaded successfully, increase
* the counter reference.
*/
- register_count = 1;
+ complete(&register_done);
leave:
- mutex_unlock(&register_count_mutex);
+ mutex_unlock(&register_done_mutex);
return ret;
}
EXPORT_SYMBOL(acpi_video_register);
void acpi_video_unregister(void)
{
- mutex_lock(&register_count_mutex);
- if (register_count) {
+ mutex_lock(&register_done_mutex);
+ if (completion_done(&register_done)) {
acpi_bus_unregister_driver(&acpi_video_bus);
- register_count = 0;
+ reinit_completion(&register_done);
}
- mutex_unlock(&register_count_mutex);
+ mutex_unlock(&register_done_mutex);
}
EXPORT_SYMBOL(acpi_video_unregister);
@@ -2094,20 +2094,21 @@ void acpi_video_unregister_backlight(void)
{
struct acpi_video_bus *video;
- mutex_lock(&register_count_mutex);
- if (register_count) {
+ mutex_lock(&register_done_mutex);
+ if (completion_done(&register_done)) {
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(&register_count_mutex);
+ mutex_unlock(&register_done_mutex);
}
bool acpi_video_handles_brightness_key_presses(void)
{
bool have_video_busses;
+ wait_for_completion(&register_done);
mutex_lock(&video_list_lock);
have_video_busses = !list_empty(&video_bus_head);
mutex_unlock(&video_list_lock);
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