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Subject[patch 5/6] Convert to use mutexes instead of semaphores
Backlight: convert to use mutexes instead of semaphores

Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
---
drivers/video/backlight/backlight.c | 89 +++++++++++++++++++++++-------------
drivers/video/backlight/lcd.c | 73 +++++++++++++++++++++--------
include/linux/backlight.h | 2
include/linux/lcd.h | 2
4 files changed, 112 insertions(+), 54 deletions(-)
Index: work/drivers/video/backlight/backlight.c
===================================================================
--- work.orig/drivers/video/backlight/backlight.c
+++ work/drivers/video/backlight/backlight.c
@@ -16,20 +16,23 @@

static ssize_t backlight_show_power(struct class_device *cdev, char *buf)
{
- int rc = -ENXIO;
+ int rc;
struct backlight_device *bd = to_backlight_device(cdev);

- down(&bd->sem);
- if (bd->props)
- rc = sprintf(buf, "%d\n", bd->props->power);
- up(&bd->sem);
+ rc = mutex_lock_interruptible(&bd->mutex);
+ if (rc)
+ return rc;
+
+ rc = bd->props ? sprintf(buf, "%d\n", bd->props->power) : -ENXIO;
+
+ mutex_unlock(&bd->mutex);

return rc;
}

static ssize_t backlight_store_power(struct class_device *cdev, const char *buf, size_t count)
{
- int rc = -ENXIO;
+ int rc;
char *endp;
struct backlight_device *bd = to_backlight_device(cdev);
int power = simple_strtoul(buf, &endp, 0);
@@ -40,35 +43,43 @@ static ssize_t backlight_store_power(str
if (size != count)
return -EINVAL;

- down(&bd->sem);
+ rc = mutex_lock_interruptible(&bd->mutex);
+ if (rc)
+ return rc;
+
if (bd->props) {
pr_debug("backlight: set power to %d\n", power);
bd->props->power = power;
if (bd->props->update_status)
bd->props->update_status(bd);
rc = count;
- }
- up(&bd->sem);
+ } else
+ rc = -ENXIO;
+
+ mutex_unlock(&bd->mutex);

return rc;
}

static ssize_t backlight_show_brightness(struct class_device *cdev, char *buf)
{
- int rc = -ENXIO;
+ int rc;
struct backlight_device *bd = to_backlight_device(cdev);

- down(&bd->sem);
- if (bd->props)
- rc = sprintf(buf, "%d\n", bd->props->brightness);
- up(&bd->sem);
+ rc = mutex_lock_interruptible(&bd->mutex);
+ if (rc)
+ return rc;
+
+ rc = bd->props ? sprintf(buf, "%d\n", bd->props->brightness) : -ENXIO;
+
+ mutex_unlock(&bd->mutex);

return rc;
}

static ssize_t backlight_store_brightness(struct class_device *cdev, const char *buf, size_t count)
{
- int rc = -ENXIO;
+ int rc;
char *endp;
struct backlight_device *bd = to_backlight_device(cdev);
int brightness = simple_strtoul(buf, &endp, 0);
@@ -79,7 +90,10 @@ static ssize_t backlight_store_brightnes
if (size != count)
return -EINVAL;

- down(&bd->sem);
+ rc = mutex_lock_interruptible(&bd->mutex);
+ if (rc)
+ return rc;
+
if (bd->props) {
if (brightness > bd->props->max_brightness)
rc = -EINVAL;
@@ -91,21 +105,26 @@ static ssize_t backlight_store_brightnes
bd->props->update_status(bd);
rc = count;
}
- }
- up(&bd->sem);
+ } else
+ rc = -ENXIO;
+
+ mutex_unlock(&bd->mutex);

return rc;
}

static ssize_t backlight_show_max_brightness(struct class_device *cdev, char *buf)
{
- int rc = -ENXIO;
+ int rc;
struct backlight_device *bd = to_backlight_device(cdev);

- down(&bd->sem);
- if (bd->props)
- rc = sprintf(buf, "%d\n", bd->props->max_brightness);
- up(&bd->sem);
+ rc = mutex_lock_interruptible(&bd->mutex);
+ if (rc)
+ return rc;
+
+ rc = bd->props ? sprintf(buf, "%d\n", bd->props->max_brightness) : -ENXIO;
+
+ mutex_unlock(&bd->mutex);

return rc;
}
@@ -113,13 +132,19 @@ static ssize_t backlight_show_max_bright
static ssize_t backlight_show_actual_brightness(struct class_device *cdev,
char *buf)
{
- int rc = -ENXIO;
+ int rc;
struct backlight_device *bd = to_backlight_device(cdev);

- down(&bd->sem);
+ rc = mutex_lock_interruptible(&bd->mutex);
+ if (rc)
+ return rc;
+
if (bd->props && bd->props->get_brightness)
rc = sprintf(buf, "%d\n", bd->props->get_brightness(bd));
- up(&bd->sem);
+ else
+ rc = -ENXIO;
+
+ mutex_unlock(&bd->mutex);

return rc;
}
@@ -161,7 +186,8 @@ static int fb_notifier_callback(struct n
return 0;

bd = container_of(self, struct backlight_device, fb_notif);
- down(&bd->sem);
+
+ mutex_lock(&bd->mutex);
if (bd->props) {
if (!bd->props->check_fb ||
bd->props->check_fb(evdata->info)) {
@@ -170,7 +196,8 @@ static int fb_notifier_callback(struct n
bd->props->update_status(bd);
}
}
- up(&bd->sem);
+ mutex_unlock(&bd->mutex);
+
return 0;
}

@@ -198,7 +225,7 @@ struct backlight_device *backlight_devic
if (!new_bd)
return ERR_PTR(-ENOMEM);

- init_MUTEX(&new_bd->sem);
+ mutex_init(&new_bd->mutex);
new_bd->props = bp;
new_bd->class_dev.class = &backlight_class;
strlcpy(new_bd->class_dev.class_id, name, KOBJ_NAME_LEN);
@@ -235,7 +262,7 @@ void backlight_device_unregister(struct

pr_debug("backlight_device_unregister: name=%s\n", bd->class_dev.class_id);

- down(&bd->sem);
+ mutex_lock(&bd->mutex);
if (bd->props && bd->props->update_status) {
bd->props->brightness = 0;
bd->props->power = 0;
@@ -243,7 +270,7 @@ void backlight_device_unregister(struct
}

bd->props = NULL;
- up(&bd->sem);
+ mutex_unlock(&bd->mutex);

fb_unregister_client(&bd->fb_notif);
class_device_unregister(&bd->class_dev);
Index: work/drivers/video/backlight/lcd.c
===================================================================
--- work.orig/drivers/video/backlight/lcd.c
+++ work/drivers/video/backlight/lcd.c
@@ -16,20 +16,26 @@

static ssize_t lcd_show_power(struct class_device *cdev, char *buf)
{
- int rc = -ENXIO;
+ int rc;
struct lcd_device *ld = to_lcd_device(cdev);

- down(&ld->sem);
+ rc = mutex_lock_interruptible(&ld->mutex);
+ if (rc)
+ return rc;
+
if (ld->props && ld->props->get_power)
rc = sprintf(buf, "%d\n", ld->props->get_power(ld));
- up(&ld->sem);
+ else
+ rc = -ENXIO;
+
+ mutex_unlock(&ld->mutex);

return rc;
}

static ssize_t lcd_store_power(struct class_device *cdev, const char *buf, size_t count)
{
- int rc = -ENXIO;
+ int rc;
char *endp;
struct lcd_device *ld = to_lcd_device(cdev);
int power = simple_strtoul(buf, &endp, 0);
@@ -40,33 +46,44 @@ static ssize_t lcd_store_power(struct cl
if (size != count)
return -EINVAL;

- down(&ld->sem);
+ rc = mutex_lock_interruptible(&ld->mutex);
+ if (rc)
+ return rc;
+
if (ld->props && ld->props->set_power) {
pr_debug("lcd: set power to %d\n", power);
ld->props->set_power(ld, power);
rc = count;
- }
- up(&ld->sem);
+ } else
+ rc = -ENXIO;
+
+ mutex_unlock(&ld->mutex);

return rc;
}

static ssize_t lcd_show_contrast(struct class_device *cdev, char *buf)
{
- int rc = -ENXIO;
+ int rc;
struct lcd_device *ld = to_lcd_device(cdev);

- down(&ld->sem);
+ rc = mutex_lock_interruptible(&ld->mutex);
+ if (rc)
+ return rc;
+
if (ld->props && ld->props->get_contrast)
rc = sprintf(buf, "%d\n", ld->props->get_contrast(ld));
- up(&ld->sem);
+ else
+ rc = -ENXIO;
+
+ mutex_unlock(&ld->mutex);

return rc;
}

static ssize_t lcd_store_contrast(struct class_device *cdev, const char *buf, size_t count)
{
- int rc = -ENXIO;
+ int rc;
char *endp;
struct lcd_device *ld = to_lcd_device(cdev);
int contrast = simple_strtoul(buf, &endp, 0);
@@ -77,13 +94,18 @@ static ssize_t lcd_store_contrast(struct
if (size != count)
return -EINVAL;

- down(&ld->sem);
+ rc = mutex_lock_interruptible(&ld->mutex);
+ if (rc)
+ return rc;
+
if (ld->props && ld->props->set_contrast) {
pr_debug("lcd: set contrast to %d\n", contrast);
ld->props->set_contrast(ld, contrast);
rc = count;
- }
- up(&ld->sem);
+ } else
+ rc = -ENXIO;
+
+ mutex_unlock(&ld->mutex);

return rc;
}
@@ -93,10 +115,16 @@ static ssize_t lcd_show_max_contrast(str
int rc = -ENXIO;
struct lcd_device *ld = to_lcd_device(cdev);

- down(&ld->sem);
+ rc = mutex_lock_interruptible(&ld->mutex);
+ if (rc)
+ return rc;
+
if (ld->props)
rc = sprintf(buf, "%d\n", ld->props->max_contrast);
- up(&ld->sem);
+ else
+ rc = -ENXIO;
+
+ mutex_unlock(&ld->mutex);

return rc;
}
@@ -104,6 +132,7 @@ static ssize_t lcd_show_max_contrast(str
static void lcd_class_release(struct class_device *dev)
{
struct lcd_device *ld = to_lcd_device(dev);
+
kfree(ld);
}

@@ -135,11 +164,13 @@ static int fb_notifier_callback(struct n
return 0;

ld = container_of(self, struct lcd_device, fb_notif);
- down(&ld->sem);
+
+ mutex_lock(&ld->mutex);
if (ld->props)
if (!ld->props->check_fb || ld->props->check_fb(evdata->info))
ld->props->set_power(ld, *(int *)evdata->data);
- up(&ld->sem);
+ mutex_unlock(&ld->mutex);
+
return 0;
}

@@ -166,7 +197,7 @@ struct lcd_device *lcd_device_register(c
if (!new_ld)
return ERR_PTR(-ENOMEM);

- init_MUTEX(&new_ld->sem);
+ mutex_init(&new_ld->mutex);
new_ld->props = lp;
new_ld->class_dev.class = &lcd_class;
strlcpy(new_ld->class_dev.class_id, name, KOBJ_NAME_LEN);
@@ -203,9 +234,9 @@ void lcd_device_unregister(struct lcd_de

pr_debug("lcd_device_unregister: name=%s\n", ld->class_dev.class_id);

- down(&ld->sem);
+ mutex_lock(&ld->mutex);
ld->props = NULL;
- up(&ld->sem);
+ mutex_unlock(&ld->mutex);

fb_unregister_client(&ld->fb_notif);
class_device_unregister(&ld->class_dev);
Index: work/include/linux/backlight.h
===================================================================
--- work.orig/include/linux/backlight.h
+++ work/include/linux/backlight.h
@@ -41,7 +41,7 @@ struct backlight_device {
/* This protects the 'props' field. If 'props' is NULL, the driver that
registered this device has been unloaded, and if class_get_devdata()
points to something in the body of that driver, it is also invalid. */
- struct semaphore sem;
+ struct mutex mutex;
/* If this is NULL, the backing module is unloaded */
struct backlight_properties *props;
/* The framebuffer notifier block */
Index: work/include/linux/lcd.h
===================================================================
--- work.orig/include/linux/lcd.h
+++ work/include/linux/lcd.h
@@ -36,7 +36,7 @@ struct lcd_device {
/* This protects the 'props' field. If 'props' is NULL, the driver that
registered this device has been unloaded, and if class_get_devdata()
points to something in the body of that driver, it is also invalid. */
- struct semaphore sem;
+ struct mutex mutex;
/* If this is NULL, the backing module is unloaded */
struct lcd_properties *props;
/* The framebuffer notifier block */
-
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