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ACPI: video: Remove acpi_video_set_dmi_backlight_type() 

acpi_video_set_dmi_backlight_type() is troublesome because it may end
up getting called after other backlight drivers have already called
acpi_video_get_backlight_type() resulting in the other drivers
already being registered even though they should not.

In case of the acpi_video backlight, acpi_video_set_dmi_backlight_type()
actually calls acpi_video_unregister_backlight() since that is often
probed earlier, leading to userspace seeing the acpi_video0 class
device being briefly available, leading to races in userspace where
udev probe-rules try to access the device and it is already gone.

All callers have been fixed to no longer call it, so remove
acpi_video_set_dmi_backlight_type() now.

This means we now also no longer need acpi_video_unregister_backlight()
for the remove acpi_video backlight after it was wrongly registered hack,
so remove that too.

Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
This commit is contained in:
Hans de Goede 2022-06-20 11:49:57 +02:00
parent 8991d7d9ad
commit 77ab9d4d44
3 changed files with 0 additions and 30 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
drivers/acpi/acpi_video.c
View File

@ -2296,16 +2296,6 @@ void acpi_video_register_backlight(void)
}
EXPORT_SYMBOL(acpi_video_register_backlight);
void acpi_video_unregister_backlight(void)
{
struct acpi_video_bus *video;
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);
}
bool acpi_video_handles_brightness_key_presses(void)
{
return may_report_brightness_keys &&

16
drivers/acpi/video_detect.c
View File

@ -38,8 +38,6 @@
#include <linux/workqueue.h>
#include <acpi/video.h>
void acpi_video_unregister_backlight(void);
static enum acpi_backlight_type acpi_backlight_cmdline = acpi_backlight_undef;
static enum acpi_backlight_type acpi_backlight_dmi = acpi_backlight_undef;
@ -817,17 +815,3 @@ bool acpi_video_backlight_use_native(void)
return __acpi_video_get_backlight_type(true) == acpi_backlight_native;
}
EXPORT_SYMBOL(acpi_video_backlight_use_native);
/*
* Set the preferred backlight interface type based on DMI info.
* This function allows DMI blacklists to be implemented by external
* platform drivers instead of putting a big blacklist in video_detect.c
*/
void acpi_video_set_dmi_backlight_type(enum acpi_backlight_type type)
{
acpi_backlight_dmi = type;
/* Remove acpi-video backlight interface if it is no longer desired */
if (acpi_video_get_backlight_type() != acpi_backlight_video)
acpi_video_unregister_backlight();
}
EXPORT_SYMBOL(acpi_video_set_dmi_backlight_type);

4
include/acpi/video.h
View File

@ -60,7 +60,6 @@ extern int acpi_video_get_edid(struct acpi_device *device, int type,
int device_id, void **edid);
extern enum acpi_backlight_type acpi_video_get_backlight_type(void);
extern bool acpi_video_backlight_use_native(void);
extern void acpi_video_set_dmi_backlight_type(enum acpi_backlight_type type);
/*
* Note: The value returned by acpi_video_handles_brightness_key_presses()
* may change over time and should not be cached.
@ -86,9 +85,6 @@ static inline bool acpi_video_backlight_use_native(void)
{
return true;
}
static inline void acpi_video_set_dmi_backlight_type(enum acpi_backlight_type type)
{
}
static inline bool acpi_video_handles_brightness_key_presses(void)
{
return false;