On Mon, Oct 20, 2014 at 6:01 PM, Bryan Wu <coolo...@gmail.com> wrote:
> On Mon, Sep 22, 2014 at 8:21 AM, Jacek Anaszewski
> <j.anaszew...@samsung.com> wrote:
>> Add a mechanism for locking LED subsystem sysfs interface.
>> This patch prepares ground for addition of LED Flash Class
>> extension, whose API will be integrated with V4L2 Flash API.
>> Such a fusion enforces introducing a locking scheme, which
>> will secure consistent access to the LED Flash Class device.
>>
>> The mechanism being introduced allows for disabling LED
>> subsystem sysfs interface by calling led_sysfs_disable function
>> and enabling it by calling led_sysfs_enable. The functions
>> alter the LED_SYSFS_DISABLE flag state and must be called
>> under mutex lock. The state of the lock is checked with use
>> of led_sysfs_is_disabled function. Such a design allows for
>> providing immediate feedback to the user space on whether
>> the LED Flash Class device is available or is under V4L2 Flash
>> sub-device control.
>>
>
> I'm good with this and will merge it soon.
>
Just merged it into my tree.
Thanks,
-Bryan
>> Signed-off-by: Jacek Anaszewski <j.anaszew...@samsung.com>
>> Acked-by: Kyungmin Park <kyungmin.p...@samsung.com>
>> Cc: Bryan Wu <coolo...@gmail.com>
>> Cc: Richard Purdie <rpur...@rpsys.net>
>> ---
>> drivers/leds/led-class.c | 19 ++++++++++++++++---
>> drivers/leds/led-core.c | 18 ++++++++++++++++++
>> drivers/leds/led-triggers.c | 16 +++++++++++++---
>> include/linux/leds.h | 32 ++++++++++++++++++++++++++++++++
>> 4 files changed, 79 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c
>> index 2e124aa2..a39ca8f 100644
>> --- a/drivers/leds/led-class.c
>> +++ b/drivers/leds/led-class.c
>> @@ -39,17 +39,27 @@ static ssize_t brightness_store(struct device *dev,
>> {
>> struct led_classdev *led_cdev = dev_get_drvdata(dev);
>> unsigned long state;
>> - ssize_t ret = -EINVAL;
>> + ssize_t ret;
>> +
>> + mutex_lock(&led_cdev->led_access);
>> +
>> + if (led_sysfs_is_disabled(led_cdev)) {
>> + ret = -EBUSY;
>> + goto unlock;
>> + }
>>
>> ret = kstrtoul(buf, 10, &state);
>> if (ret)
>> - return ret;
>> + goto unlock;
>>
>> if (state == LED_OFF)
>> led_trigger_remove(led_cdev);
>> __led_set_brightness(led_cdev, state);
>>
>> - return size;
>> + ret = size;
>> +unlock:
>> + mutex_unlock(&led_cdev->led_access);
>> + return ret;
>> }
>> static DEVICE_ATTR_RW(brightness);
>>
>> @@ -213,6 +223,7 @@ int led_classdev_register(struct device *parent, struct
>> led_classdev *led_cdev)
>> #ifdef CONFIG_LEDS_TRIGGERS
>> init_rwsem(&led_cdev->trigger_lock);
>> #endif
>> + mutex_init(&led_cdev->led_access);
>> /* add to the list of leds */
>> down_write(&leds_list_lock);
>> list_add_tail(&led_cdev->node, &leds_list);
>> @@ -266,6 +277,8 @@ void led_classdev_unregister(struct led_classdev
>> *led_cdev)
>> down_write(&leds_list_lock);
>> list_del(&led_cdev->node);
>> up_write(&leds_list_lock);
>> +
>> + mutex_destroy(&led_cdev->led_access);
>> }
>> EXPORT_SYMBOL_GPL(led_classdev_unregister);
>>
>> diff --git a/drivers/leds/led-core.c b/drivers/leds/led-core.c
>> index 0d15aa9..cca86ab 100644
>> --- a/drivers/leds/led-core.c
>> +++ b/drivers/leds/led-core.c
>> @@ -142,3 +142,21 @@ int led_update_brightness(struct led_classdev *led_cdev)
>> return ret;
>> }
>> EXPORT_SYMBOL(led_update_brightness);
>> +
>> +/* Caller must ensure led_cdev->led_access held */
>> +void led_sysfs_disable(struct led_classdev *led_cdev)
>> +{
>> + lockdep_assert_held(&led_cdev->led_access);
>> +
>> + led_cdev->flags |= LED_SYSFS_DISABLE;
>> +}
>> +EXPORT_SYMBOL_GPL(led_sysfs_disable);
>> +
>> +/* Caller must ensure led_cdev->led_access held */
>> +void led_sysfs_enable(struct led_classdev *led_cdev)
>> +{
>> + lockdep_assert_held(&led_cdev->led_access);
>> +
>> + led_cdev->flags &= ~LED_SYSFS_DISABLE;
>> +}
>> +EXPORT_SYMBOL_GPL(led_sysfs_enable);
>> diff --git a/drivers/leds/led-triggers.c b/drivers/leds/led-triggers.c
>> index c3734f1..e8b1120 100644
>> --- a/drivers/leds/led-triggers.c
>> +++ b/drivers/leds/led-triggers.c
>> @@ -37,6 +37,14 @@ ssize_t led_trigger_store(struct device *dev, struct
>> device_attribute *attr,
>> char trigger_name[TRIG_NAME_MAX];
>> struct led_trigger *trig;
>> size_t len;
>> + int ret = count;
>> +
>> + mutex_lock(&led_cdev->led_access);
>> +
>> + if (led_sysfs_is_disabled(led_cdev)) {
>> + ret = -EBUSY;
>> + goto unlock;
>> + }
>>
>> trigger_name[sizeof(trigger_name) - 1] = '\0';
>> strncpy(trigger_name, buf, sizeof(trigger_name) - 1);
>> @@ -47,7 +55,7 @@ ssize_t led_trigger_store(struct device *dev, struct
>> device_attribute *attr,
>>
>> if (!strcmp(trigger_name, "none")) {
>> led_trigger_remove(led_cdev);
>> - return count;
>> + goto unlock;
>> }
>>
>> down_read(&triggers_list_lock);
>> @@ -58,12 +66,14 @@ ssize_t led_trigger_store(struct device *dev, struct
>> device_attribute *attr,
>> up_write(&led_cdev->trigger_lock);
>>
>> up_read(&triggers_list_lock);
>> - return count;
>> + goto unlock;
>> }
>> }
>> up_read(&triggers_list_lock);
>>
>> - return -EINVAL;
>> +unlock:
>> + mutex_unlock(&led_cdev->led_access);
>> + return ret;
>> }
>> EXPORT_SYMBOL_GPL(led_trigger_store);
>>
>> diff --git a/include/linux/leds.h b/include/linux/leds.h
>> index f8b2f58..44c8a98 100644
>> --- a/include/linux/leds.h
>> +++ b/include/linux/leds.h
>> @@ -13,6 +13,7 @@
>> #define __LINUX_LEDS_H_INCLUDED
>>
>> #include <linux/list.h>
>> +#include <linux/mutex.h>
>> #include <linux/rwsem.h>
>> #include <linux/spinlock.h>
>> #include <linux/timer.h>
>> @@ -42,6 +43,7 @@ struct led_classdev {
>> #define LED_BLINK_ONESHOT (1 << 17)
>> #define LED_BLINK_ONESHOT_STOP (1 << 18)
>> #define LED_BLINK_INVERT (1 << 19)
>> +#define LED_SYSFS_DISABLE (1 << 20)
>>
>> /* Set LED brightness level */
>> /* Must not sleep, use a workqueue if needed */
>> @@ -85,6 +87,9 @@ struct led_classdev {
>> /* true if activated - deactivate routine uses it to do cleanup */
>> bool activated;
>> #endif
>> +
>> + /* Ensures consistent access to the LED Flash Class device */
>> + struct mutex led_access;
>> };
>>
>> extern int led_classdev_register(struct device *parent,
>> @@ -151,6 +156,33 @@ extern void led_set_brightness(struct led_classdev
>> *led_cdev,
>> */
>> extern int led_update_brightness(struct led_classdev *led_cdev);
>>
>> +/**
>> + * led_sysfs_disable - disable LED sysfs interface
>> + * @led_cdev: the LED to set
>> + *
>> + * Disable the led_cdev's sysfs interface.
>> + */
>> +extern void led_sysfs_disable(struct led_classdev *led_cdev);
>> +
>> +/**
>> + * led_sysfs_enable - enable LED sysfs interface
>> + * @led_cdev: the LED to set
>> + *
>> + * Enable the led_cdev's sysfs interface.
>> + */
>> +extern void led_sysfs_enable(struct led_classdev *led_cdev);
>> +
>> +/**
>> + * led_sysfs_is_disabled - check if LED sysfs interface is disabled
>> + * @led_cdev: the LED to query
>> + *
>> + * Returns: true if the led_cdev's sysfs interface is disabled.
>> + */
>> +static inline bool led_sysfs_is_disabled(struct led_classdev *led_cdev)
>> +{
>> + return led_cdev->flags & LED_SYSFS_DISABLE;
>> +}
>> +
>> /*
>> * LED Triggers
>> */
>> --
>> 1.7.9.5
>>
--
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