| Message ID | 1408542118-32723-3-git-send-email-j.anaszewski@samsung.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Wed, Aug 20, 2014 at 6:41 AM, Jacek Anaszewski <j.anaszewski@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_lock function > and enabling it by calling led_sysfs_unlock. The functions > alter the LED_SYSFS_LOCK flag state and must be called > under mutex lock. The state of the lock is checked with use > of led_sysfs_is_locked 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. > > Signed-off-by: Jacek Anaszewski <j.anaszewski@samsung.com> > Acked-by: Kyungmin Park <kyungmin.park@samsung.com> > Cc: Bryan Wu <cooloney@gmail.com> > Cc: Richard Purdie <rpurdie@rpsys.net> > --- > drivers/leds/led-class.c | 23 ++++++++++++++++++++--- > drivers/leds/led-core.c | 18 ++++++++++++++++++ > drivers/leds/led-triggers.c | 15 ++++++++++++--- > include/linux/leds.h | 32 ++++++++++++++++++++++++++++++++ > 4 files changed, 82 insertions(+), 6 deletions(-) > > diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c > index 6f82a76..0bc0ba9 100644 > --- a/drivers/leds/led-class.c > +++ b/drivers/leds/led-class.c > @@ -39,17 +39,31 @@ 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; > + > +#ifdef CONFIG_V4L2_FLASH_LED_CLASS Can we remove this #ifdef? Following code looks good to the common LED class. > + mutex_lock(&led_cdev->led_lock); Can we choose more meaningful name instead of led_lock here? Then use led_sysfs_enable() instead of led_sysfs_unlock() led_sysfs_disable instead of led_sysfs_lock() led_sysfs_is_disabled instead of led_sysfs_is_locked() And the flag LED_SYSFS_LOCK -> LED_SYSFS_DISABLE I was just confused by the name lock and unlock and mutex lock. The idea looks good to me. Thanks, -Bryan > + > + if (led_sysfs_is_locked(led_cdev)) { > + ret = -EBUSY; > + goto unlock; > + } > +#endif > > 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: > +#ifdef CONFIG_V4L2_FLASH_LED_CLASS > + mutex_unlock(&led_cdev->led_lock); > +#endif > + return ret; > } > static DEVICE_ATTR_RW(brightness); > > @@ -215,6 +229,7 @@ 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_lock); > /* add to the list of leds */ > down_write(&leds_list_lock); > list_add_tail(&led_cdev->node, &leds_list); > @@ -266,6 +281,8 @@ 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_lock); > } > EXPORT_SYMBOL_GPL(led_classdev_unregister); > > diff --git a/drivers/leds/led-core.c b/drivers/leds/led-core.c > index 466ce5a..4649ea5 100644 > --- a/drivers/leds/led-core.c > +++ b/drivers/leds/led-core.c > @@ -143,3 +143,21 @@ int led_update_brightness(struct led_classdev *led_cdev) > return ret; > } > EXPORT_SYMBOL(led_update_brightness); > + > +/* Caller must ensure led_cdev->led_lock held */ > +void led_sysfs_lock(struct led_classdev *led_cdev) > +{ > + lockdep_assert_held(&led_cdev->led_lock); > + > + led_cdev->flags |= LED_SYSFS_LOCK; > +} > +EXPORT_SYMBOL_GPL(led_sysfs_lock); > + > +/* Caller must ensure led_cdev->led_lock held */ > +void led_sysfs_unlock(struct led_classdev *led_cdev) > +{ > + lockdep_assert_held(&led_cdev->led_lock); > + > + led_cdev->flags &= ~LED_SYSFS_LOCK; > +} > +EXPORT_SYMBOL_GPL(led_sysfs_unlock); > diff --git a/drivers/leds/led-triggers.c b/drivers/leds/led-triggers.c > index c3734f1..d391a5d 100644 > --- a/drivers/leds/led-triggers.c > +++ b/drivers/leds/led-triggers.c > @@ -37,6 +37,11 @@ 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; > + > +#ifdef CONFIG_V4L2_FLASH_LED_CLASS > + mutex_lock(&led_cdev->led_lock); > +#endif > > trigger_name[sizeof(trigger_name) - 1] = '\0'; > strncpy(trigger_name, buf, sizeof(trigger_name) - 1); > @@ -47,7 +52,7 @@ 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 exit_unlock; > } > > down_read(&triggers_list_lock); > @@ -58,12 +63,16 @@ 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 exit_unlock; > } > } > up_read(&triggers_list_lock); > > - return -EINVAL; > +exit_unlock: > +#ifdef CONFIG_V4L2_FLASH_LED_CLASS > + mutex_unlock(&led_cdev->led_lock); > +#endif > + return ret; > } > EXPORT_SYMBOL_GPL(led_trigger_store); > > diff --git a/include/linux/leds.h b/include/linux/leds.h > index cc85b16..ef343f1 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/workqueue.h> > @@ -41,6 +42,7 @@ 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_LOCK (1 << 20) > > /* Set LED brightness level */ > /* Must not sleep, use a workqueue if needed */ > @@ -84,6 +86,9 @@ 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_lock; > }; > > extern int led_classdev_register(struct device *parent, > @@ -150,6 +155,33 @@ extern void led_set_brightness(struct led_classdev *led_cdev, > */ > extern int led_update_brightness(struct led_classdev *led_cdev); > > +/** > + * led_sysfs_lock - lock LED sysfs interface > + * @led_cdev: the LED to set > + * > + * Lock the LED's sysfs interface > + */ > +extern void led_sysfs_lock(struct led_classdev *led_cdev); > + > +/** > + * led_sysfs_unlock - unlock LED sysfs interface > + * @led_cdev: the LED to set > + * > + * Unlock the LED's sysfs interface > + */ > +extern void led_sysfs_unlock(struct led_classdev *led_cdev); > + > +/** > + * led_sysfs_is_locked > + * @led_cdev: the LED to query > + * > + * Returns: true if the sysfs interface of the led is locked > + */ > +static inline bool led_sysfs_is_locked(struct led_classdev *led_cdev) > +{ > + return led_cdev->flags & LED_SYSFS_LOCK; > +} > + > /* > * LED Triggers > */ > -- > 1.7.9.5 > -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Hi Bryan, Thanks for a review. On 09/12/2014 03:11 AM, Bryan Wu wrote: > On Wed, Aug 20, 2014 at 6:41 AM, Jacek Anaszewski > <j.anaszewski@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_lock function >> and enabling it by calling led_sysfs_unlock. The functions >> alter the LED_SYSFS_LOCK flag state and must be called >> under mutex lock. The state of the lock is checked with use >> of led_sysfs_is_locked 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. >> >> Signed-off-by: Jacek Anaszewski <j.anaszewski@samsung.com> >> Acked-by: Kyungmin Park <kyungmin.park@samsung.com> >> Cc: Bryan Wu <cooloney@gmail.com> >> Cc: Richard Purdie <rpurdie@rpsys.net> >> --- >> drivers/leds/led-class.c | 23 ++++++++++++++++++++--- >> drivers/leds/led-core.c | 18 ++++++++++++++++++ >> drivers/leds/led-triggers.c | 15 ++++++++++++--- >> include/linux/leds.h | 32 ++++++++++++++++++++++++++++++++ >> 4 files changed, 82 insertions(+), 6 deletions(-) >> >> diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c >> index 6f82a76..0bc0ba9 100644 >> --- a/drivers/leds/led-class.c >> +++ b/drivers/leds/led-class.c >> @@ -39,17 +39,31 @@ 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; >> + >> +#ifdef CONFIG_V4L2_FLASH_LED_CLASS > > Can we remove this #ifdef? Following code looks good to the common LED class. Sure. >> + mutex_lock(&led_cdev->led_lock); > > Can we choose more meaningful name instead of led_lock here? > Then use led_sysfs_enable() instead of led_sysfs_unlock() > led_sysfs_disable instead of led_sysfs_lock() > led_sysfs_is_disabled instead of led_sysfs_is_locked() > > And the flag LED_SYSFS_LOCK -> LED_SYSFS_DISABLE > > I was just confused by the name lock and unlock and mutex lock. > > The idea looks good to me. Indeed, this naming will be more intuitive. Regards, Jacek -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c index 6f82a76..0bc0ba9 100644 --- a/drivers/leds/led-class.c +++ b/drivers/leds/led-class.c @@ -39,17 +39,31 @@ 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; + +#ifdef CONFIG_V4L2_FLASH_LED_CLASS + mutex_lock(&led_cdev->led_lock); + + if (led_sysfs_is_locked(led_cdev)) { + ret = -EBUSY; + goto unlock; + } +#endif 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: +#ifdef CONFIG_V4L2_FLASH_LED_CLASS + mutex_unlock(&led_cdev->led_lock); +#endif + return ret; } static DEVICE_ATTR_RW(brightness); @@ -215,6 +229,7 @@ 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_lock); /* add to the list of leds */ down_write(&leds_list_lock); list_add_tail(&led_cdev->node, &leds_list); @@ -266,6 +281,8 @@ 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_lock); } EXPORT_SYMBOL_GPL(led_classdev_unregister); diff --git a/drivers/leds/led-core.c b/drivers/leds/led-core.c index 466ce5a..4649ea5 100644 --- a/drivers/leds/led-core.c +++ b/drivers/leds/led-core.c @@ -143,3 +143,21 @@ int led_update_brightness(struct led_classdev *led_cdev) return ret; } EXPORT_SYMBOL(led_update_brightness); + +/* Caller must ensure led_cdev->led_lock held */ +void led_sysfs_lock(struct led_classdev *led_cdev) +{ + lockdep_assert_held(&led_cdev->led_lock); + + led_cdev->flags |= LED_SYSFS_LOCK; +} +EXPORT_SYMBOL_GPL(led_sysfs_lock); + +/* Caller must ensure led_cdev->led_lock held */ +void led_sysfs_unlock(struct led_classdev *led_cdev) +{ + lockdep_assert_held(&led_cdev->led_lock); + + led_cdev->flags &= ~LED_SYSFS_LOCK; +} +EXPORT_SYMBOL_GPL(led_sysfs_unlock); diff --git a/drivers/leds/led-triggers.c b/drivers/leds/led-triggers.c index c3734f1..d391a5d 100644 --- a/drivers/leds/led-triggers.c +++ b/drivers/leds/led-triggers.c @@ -37,6 +37,11 @@ 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; + +#ifdef CONFIG_V4L2_FLASH_LED_CLASS + mutex_lock(&led_cdev->led_lock); +#endif trigger_name[sizeof(trigger_name) - 1] = '\0'; strncpy(trigger_name, buf, sizeof(trigger_name) - 1); @@ -47,7 +52,7 @@ 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 exit_unlock; } down_read(&triggers_list_lock); @@ -58,12 +63,16 @@ 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 exit_unlock; } } up_read(&triggers_list_lock); - return -EINVAL; +exit_unlock: +#ifdef CONFIG_V4L2_FLASH_LED_CLASS + mutex_unlock(&led_cdev->led_lock); +#endif + return ret; } EXPORT_SYMBOL_GPL(led_trigger_store); diff --git a/include/linux/leds.h b/include/linux/leds.h index cc85b16..ef343f1 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/workqueue.h> @@ -41,6 +42,7 @@ 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_LOCK (1 << 20) /* Set LED brightness level */ /* Must not sleep, use a workqueue if needed */ @@ -84,6 +86,9 @@ 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_lock; }; extern int led_classdev_register(struct device *parent, @@ -150,6 +155,33 @@ extern void led_set_brightness(struct led_classdev *led_cdev, */ extern int led_update_brightness(struct led_classdev *led_cdev); +/** + * led_sysfs_lock - lock LED sysfs interface + * @led_cdev: the LED to set + * + * Lock the LED's sysfs interface + */ +extern void led_sysfs_lock(struct led_classdev *led_cdev); + +/** + * led_sysfs_unlock - unlock LED sysfs interface + * @led_cdev: the LED to set + * + * Unlock the LED's sysfs interface + */ +extern void led_sysfs_unlock(struct led_classdev *led_cdev); + +/** + * led_sysfs_is_locked + * @led_cdev: the LED to query + * + * Returns: true if the sysfs interface of the led is locked + */ +static inline bool led_sysfs_is_locked(struct led_classdev *led_cdev) +{ + return led_cdev->flags & LED_SYSFS_LOCK; +} + /* * LED Triggers */