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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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