| Message ID | 20240820155407.32729-1-ddrokosov@salutedevices.com |
|---|---|
| State | Superseded |
| Headers | show |
| Series | [v1] leds: introduce ordered workqueue for leds events instead of system_wq | expand |
INTENTIONAL TOP POST: This is going to need more time on the list and hopefully draws the attention of some potentially affected users / to-be testers. > This allows to setup ordered workqueue for leds events. This may be > useful, because default 'system_wq' does not guarantee execution order > of each work_struct, thus for several brightness update requests (for > multiple leds), real brightness switch could be in random order. > > Yes, for sysfs-based leds we have flush_work() call inside > brightness_store() operation, but it's blocking call, so userspace > caller can be blocked at a long time, which means leds animation stream > can be broken. > > Ordered workqueue has the same behaviour as system_wq + flush_work(), > but all scheduled works are async and userspace caller is not blocked, > which it better for userspace animation scheduling. > > Signed-off-by: Alexey Romanov <avromanov@salutedevices.com> > Signed-off-by: Dmitry Rokosov <ddrokosov@salutedevices.com> > --- > drivers/leds/led-class.c | 12 +++++++++++- > drivers/leds/led-core.c | 6 +++--- > include/linux/leds.h | 1 + > 3 files changed, 15 insertions(+), 4 deletions(-) > > diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c > index ba1be15cfd8e..fba12471cf1f 100644 > --- a/drivers/leds/led-class.c > +++ b/drivers/leds/led-class.c > @@ -25,6 +25,8 @@ > static DEFINE_MUTEX(leds_lookup_lock); > static LIST_HEAD(leds_lookup_list); > > +static struct workqueue_struct *leds_wq; > + > static ssize_t brightness_show(struct device *dev, > struct device_attribute *attr, char *buf) > { > @@ -57,7 +59,6 @@ static ssize_t brightness_store(struct device *dev, > if (state == LED_OFF) > led_trigger_remove(led_cdev); > led_set_brightness(led_cdev, state); > - flush_work(&led_cdev->set_brightness_work); > > ret = size; > unlock: > @@ -549,6 +550,8 @@ int led_classdev_register_ext(struct device *parent, > > led_update_brightness(led_cdev); > > + led_cdev->wq = leds_wq; > + > led_init_core(led_cdev); > > #ifdef CONFIG_LEDS_TRIGGERS > @@ -667,12 +670,19 @@ EXPORT_SYMBOL_GPL(devm_led_classdev_unregister); > > static int __init leds_init(void) > { > + leds_wq = alloc_ordered_workqueue("leds", 0); > + if (!leds_wq) { > + pr_err("failed to create leds ordered workqueue\n"); > + return -ENOMEM; > + } > + > return class_register(&leds_class); > } > > static void __exit leds_exit(void) > { > class_unregister(&leds_class); > + destroy_workqueue(leds_wq); > } > > subsys_initcall(leds_init); > diff --git a/drivers/leds/led-core.c b/drivers/leds/led-core.c > index 89c9806cc97f..9769ac49be20 100644 > --- a/drivers/leds/led-core.c > +++ b/drivers/leds/led-core.c > @@ -266,7 +266,7 @@ void led_blink_set_nosleep(struct led_classdev *led_cdev, unsigned long delay_on > led_cdev->delayed_delay_on = delay_on; > led_cdev->delayed_delay_off = delay_off; > set_bit(LED_SET_BLINK, &led_cdev->work_flags); > - schedule_work(&led_cdev->set_brightness_work); > + queue_work(led_cdev->wq, &led_cdev->set_brightness_work); > return; > } > > @@ -297,7 +297,7 @@ void led_set_brightness(struct led_classdev *led_cdev, unsigned int brightness) > */ > if (!brightness) { > set_bit(LED_BLINK_DISABLE, &led_cdev->work_flags); > - schedule_work(&led_cdev->set_brightness_work); > + queue_work(led_cdev->wq, &led_cdev->set_brightness_work); > } else { > set_bit(LED_BLINK_BRIGHTNESS_CHANGE, > &led_cdev->work_flags); > @@ -333,7 +333,7 @@ void led_set_brightness_nopm(struct led_classdev *led_cdev, unsigned int value) > set_bit(LED_SET_BRIGHTNESS_OFF, &led_cdev->work_flags); > } > > - schedule_work(&led_cdev->set_brightness_work); > + queue_work(led_cdev->wq, &led_cdev->set_brightness_work); > } > EXPORT_SYMBOL_GPL(led_set_brightness_nopm); > > diff --git a/include/linux/leds.h b/include/linux/leds.h > index 6300313c46b7..7c9f1cb12ab9 100644 > --- a/include/linux/leds.h > +++ b/include/linux/leds.h > @@ -169,6 +169,7 @@ struct led_classdev { > int new_blink_brightness; > void (*flash_resume)(struct led_classdev *led_cdev); > > + struct workqueue_struct *wq; /* LED workqueue */ > struct work_struct set_brightness_work; > int delayed_set_value; > unsigned long delayed_delay_on; > -- > 2.43.0 > >
On Thu, 22 Aug 2024, Lee Jones wrote: > INTENTIONAL TOP POST: > > This is going to need more time on the list and hopefully draws the > attention of some potentially affected users / to-be testers. Another call for users to test this before I review/apply it. Plan is to rotate it in to -next just after -rc1 has been released. That should give it quite a few weeks in -next for people to test. > > This allows to setup ordered workqueue for leds events. This may be > > useful, because default 'system_wq' does not guarantee execution order > > of each work_struct, thus for several brightness update requests (for > > multiple leds), real brightness switch could be in random order. > > > > Yes, for sysfs-based leds we have flush_work() call inside > > brightness_store() operation, but it's blocking call, so userspace > > caller can be blocked at a long time, which means leds animation stream > > can be broken. > > > > Ordered workqueue has the same behaviour as system_wq + flush_work(), > > but all scheduled works are async and userspace caller is not blocked, > > which it better for userspace animation scheduling. > > > > Signed-off-by: Alexey Romanov <avromanov@salutedevices.com> > > Signed-off-by: Dmitry Rokosov <ddrokosov@salutedevices.com> > > --- > > drivers/leds/led-class.c | 12 +++++++++++- > > drivers/leds/led-core.c | 6 +++--- > > include/linux/leds.h | 1 + > > 3 files changed, 15 insertions(+), 4 deletions(-) > > > > diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c > > index ba1be15cfd8e..fba12471cf1f 100644 > > --- a/drivers/leds/led-class.c > > +++ b/drivers/leds/led-class.c > > @@ -25,6 +25,8 @@ > > static DEFINE_MUTEX(leds_lookup_lock); > > static LIST_HEAD(leds_lookup_list); > > > > +static struct workqueue_struct *leds_wq; > > + > > static ssize_t brightness_show(struct device *dev, > > struct device_attribute *attr, char *buf) > > { > > @@ -57,7 +59,6 @@ static ssize_t brightness_store(struct device *dev, > > if (state == LED_OFF) > > led_trigger_remove(led_cdev); > > led_set_brightness(led_cdev, state); > > - flush_work(&led_cdev->set_brightness_work); > > > > ret = size; > > unlock: > > @@ -549,6 +550,8 @@ int led_classdev_register_ext(struct device *parent, > > > > led_update_brightness(led_cdev); > > > > + led_cdev->wq = leds_wq; > > + > > led_init_core(led_cdev); > > > > #ifdef CONFIG_LEDS_TRIGGERS > > @@ -667,12 +670,19 @@ EXPORT_SYMBOL_GPL(devm_led_classdev_unregister); > > > > static int __init leds_init(void) > > { > > + leds_wq = alloc_ordered_workqueue("leds", 0); > > + if (!leds_wq) { > > + pr_err("failed to create leds ordered workqueue\n"); > > + return -ENOMEM; > > + } > > + > > return class_register(&leds_class); > > } > > > > static void __exit leds_exit(void) > > { > > class_unregister(&leds_class); > > + destroy_workqueue(leds_wq); > > } > > > > subsys_initcall(leds_init); > > diff --git a/drivers/leds/led-core.c b/drivers/leds/led-core.c > > index 89c9806cc97f..9769ac49be20 100644 > > --- a/drivers/leds/led-core.c > > +++ b/drivers/leds/led-core.c > > @@ -266,7 +266,7 @@ void led_blink_set_nosleep(struct led_classdev *led_cdev, unsigned long delay_on > > led_cdev->delayed_delay_on = delay_on; > > led_cdev->delayed_delay_off = delay_off; > > set_bit(LED_SET_BLINK, &led_cdev->work_flags); > > - schedule_work(&led_cdev->set_brightness_work); > > + queue_work(led_cdev->wq, &led_cdev->set_brightness_work); > > return; > > } > > > > @@ -297,7 +297,7 @@ void led_set_brightness(struct led_classdev *led_cdev, unsigned int brightness) > > */ > > if (!brightness) { > > set_bit(LED_BLINK_DISABLE, &led_cdev->work_flags); > > - schedule_work(&led_cdev->set_brightness_work); > > + queue_work(led_cdev->wq, &led_cdev->set_brightness_work); > > } else { > > set_bit(LED_BLINK_BRIGHTNESS_CHANGE, > > &led_cdev->work_flags); > > @@ -333,7 +333,7 @@ void led_set_brightness_nopm(struct led_classdev *led_cdev, unsigned int value) > > set_bit(LED_SET_BRIGHTNESS_OFF, &led_cdev->work_flags); > > } > > > > - schedule_work(&led_cdev->set_brightness_work); > > + queue_work(led_cdev->wq, &led_cdev->set_brightness_work); > > } > > EXPORT_SYMBOL_GPL(led_set_brightness_nopm); > > > > diff --git a/include/linux/leds.h b/include/linux/leds.h > > index 6300313c46b7..7c9f1cb12ab9 100644 > > --- a/include/linux/leds.h > > +++ b/include/linux/leds.h > > @@ -169,6 +169,7 @@ struct led_classdev { > > int new_blink_brightness; > > void (*flash_resume)(struct led_classdev *led_cdev); > > > > + struct workqueue_struct *wq; /* LED workqueue */ > > struct work_struct set_brightness_work; > > int delayed_set_value; > > unsigned long delayed_delay_on; > > -- > > 2.43.0 > > > > > > -- > Lee Jones [李琼斯]
On Tue, Sep 03, 2024 at 03:01:19PM +0100, Lee Jones wrote: > On Tue, 20 Aug 2024, Dmitry Rokosov wrote: > > > This allows to setup ordered workqueue for leds events. This may be > > useful, because default 'system_wq' does not guarantee execution order > > of each work_struct, thus for several brightness update requests (for > > multiple leds), real brightness switch could be in random order. > > > > Yes, for sysfs-based leds we have flush_work() call inside > > brightness_store() operation, but it's blocking call, so userspace > > caller can be blocked at a long time, which means leds animation stream > > can be broken. > > > > Ordered workqueue has the same behaviour as system_wq + flush_work(), > > but all scheduled works are async and userspace caller is not blocked, > > which it better for userspace animation scheduling. > > > > Signed-off-by: Alexey Romanov <avromanov@salutedevices.com> > > Signed-off-by: Dmitry Rokosov <ddrokosov@salutedevices.com> > > --- > > drivers/leds/led-class.c | 12 +++++++++++- > > drivers/leds/led-core.c | 6 +++--- > > include/linux/leds.h | 1 + > > 3 files changed, 15 insertions(+), 4 deletions(-) > > > > diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c > > index ba1be15cfd8e..fba12471cf1f 100644 > > --- a/drivers/leds/led-class.c > > +++ b/drivers/leds/led-class.c > > @@ -25,6 +25,8 @@ > > static DEFINE_MUTEX(leds_lookup_lock); > > static LIST_HEAD(leds_lookup_list); > > > > +static struct workqueue_struct *leds_wq; > > Does this _have_ to be global? > Unfortunately, yes, it has. Each LED described in the DTS, for example, is represented as led_cdev. We do not have a led_device or a similar structure to represent the entire LED device (the controller that integrates all LEDs and manages them). One option is to move leds_wq to the driver’s private data. However, from my perspective, this is a more complicated solution, especially considering that we have the ability to create a global leds_wq variable in the core implementation, which can resolve the described issue entirely. > Isn't there a suitable data structure that we can store it in? > > > static ssize_t brightness_show(struct device *dev, > > struct device_attribute *attr, char *buf) > > { > > @@ -57,7 +59,6 @@ static ssize_t brightness_store(struct device *dev, > > if (state == LED_OFF) > > led_trigger_remove(led_cdev); > > led_set_brightness(led_cdev, state); > > - flush_work(&led_cdev->set_brightness_work); > > > > ret = size; > > unlock: > > @@ -549,6 +550,8 @@ int led_classdev_register_ext(struct device *parent, > > > > led_update_brightness(led_cdev); > > > > + led_cdev->wq = leds_wq; > > + > > led_init_core(led_cdev); > > > > #ifdef CONFIG_LEDS_TRIGGERS > > @@ -667,12 +670,19 @@ EXPORT_SYMBOL_GPL(devm_led_classdev_unregister); > > > > static int __init leds_init(void) > > { > > + leds_wq = alloc_ordered_workqueue("leds", 0); > > + if (!leds_wq) { > > + pr_err("failed to create leds ordered workqueue\n"); > > Nit: "LEDs" > Okay, I will send v2 patch today with fixed this line. > > + return -ENOMEM; > > + } > > + > > return class_register(&leds_class); > > } > > > > static void __exit leds_exit(void) > > { > > class_unregister(&leds_class); > > + destroy_workqueue(leds_wq); > > } > > > > subsys_initcall(leds_init); > > diff --git a/drivers/leds/led-core.c b/drivers/leds/led-core.c > > index 89c9806cc97f..9769ac49be20 100644 > > --- a/drivers/leds/led-core.c > > +++ b/drivers/leds/led-core.c > > @@ -266,7 +266,7 @@ void led_blink_set_nosleep(struct led_classdev *led_cdev, unsigned long delay_on > > led_cdev->delayed_delay_on = delay_on; > > led_cdev->delayed_delay_off = delay_off; > > set_bit(LED_SET_BLINK, &led_cdev->work_flags); > > - schedule_work(&led_cdev->set_brightness_work); > > + queue_work(led_cdev->wq, &led_cdev->set_brightness_work); > > return; > > } > > > > @@ -297,7 +297,7 @@ void led_set_brightness(struct led_classdev *led_cdev, unsigned int brightness) > > */ > > if (!brightness) { > > set_bit(LED_BLINK_DISABLE, &led_cdev->work_flags); > > - schedule_work(&led_cdev->set_brightness_work); > > + queue_work(led_cdev->wq, &led_cdev->set_brightness_work); > > } else { > > set_bit(LED_BLINK_BRIGHTNESS_CHANGE, > > &led_cdev->work_flags); > > @@ -333,7 +333,7 @@ void led_set_brightness_nopm(struct led_classdev *led_cdev, unsigned int value) > > set_bit(LED_SET_BRIGHTNESS_OFF, &led_cdev->work_flags); > > } > > > > - schedule_work(&led_cdev->set_brightness_work); > > + queue_work(led_cdev->wq, &led_cdev->set_brightness_work); > > } > > EXPORT_SYMBOL_GPL(led_set_brightness_nopm); > > > > diff --git a/include/linux/leds.h b/include/linux/leds.h > > index 6300313c46b7..7c9f1cb12ab9 100644 > > --- a/include/linux/leds.h > > +++ b/include/linux/leds.h > > @@ -169,6 +169,7 @@ struct led_classdev { > > int new_blink_brightness; > > void (*flash_resume)(struct led_classdev *led_cdev); > > > > + struct workqueue_struct *wq; /* LED workqueue */ > > struct work_struct set_brightness_work; > > int delayed_set_value; > > unsigned long delayed_delay_on; > > -- > > 2.43.0 > > > > > > -- > Lee Jones [李琼斯]
diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c index ba1be15cfd8e..fba12471cf1f 100644 --- a/drivers/leds/led-class.c +++ b/drivers/leds/led-class.c @@ -25,6 +25,8 @@ static DEFINE_MUTEX(leds_lookup_lock); static LIST_HEAD(leds_lookup_list); +static struct workqueue_struct *leds_wq; + static ssize_t brightness_show(struct device *dev, struct device_attribute *attr, char *buf) { @@ -57,7 +59,6 @@ static ssize_t brightness_store(struct device *dev, if (state == LED_OFF) led_trigger_remove(led_cdev); led_set_brightness(led_cdev, state); - flush_work(&led_cdev->set_brightness_work); ret = size; unlock: @@ -549,6 +550,8 @@ int led_classdev_register_ext(struct device *parent, led_update_brightness(led_cdev); + led_cdev->wq = leds_wq; + led_init_core(led_cdev); #ifdef CONFIG_LEDS_TRIGGERS @@ -667,12 +670,19 @@ EXPORT_SYMBOL_GPL(devm_led_classdev_unregister); static int __init leds_init(void) { + leds_wq = alloc_ordered_workqueue("leds", 0); + if (!leds_wq) { + pr_err("failed to create leds ordered workqueue\n"); + return -ENOMEM; + } + return class_register(&leds_class); } static void __exit leds_exit(void) { class_unregister(&leds_class); + destroy_workqueue(leds_wq); } subsys_initcall(leds_init); diff --git a/drivers/leds/led-core.c b/drivers/leds/led-core.c index 89c9806cc97f..9769ac49be20 100644 --- a/drivers/leds/led-core.c +++ b/drivers/leds/led-core.c @@ -266,7 +266,7 @@ void led_blink_set_nosleep(struct led_classdev *led_cdev, unsigned long delay_on led_cdev->delayed_delay_on = delay_on; led_cdev->delayed_delay_off = delay_off; set_bit(LED_SET_BLINK, &led_cdev->work_flags); - schedule_work(&led_cdev->set_brightness_work); + queue_work(led_cdev->wq, &led_cdev->set_brightness_work); return; } @@ -297,7 +297,7 @@ void led_set_brightness(struct led_classdev *led_cdev, unsigned int brightness) */ if (!brightness) { set_bit(LED_BLINK_DISABLE, &led_cdev->work_flags); - schedule_work(&led_cdev->set_brightness_work); + queue_work(led_cdev->wq, &led_cdev->set_brightness_work); } else { set_bit(LED_BLINK_BRIGHTNESS_CHANGE, &led_cdev->work_flags); @@ -333,7 +333,7 @@ void led_set_brightness_nopm(struct led_classdev *led_cdev, unsigned int value) set_bit(LED_SET_BRIGHTNESS_OFF, &led_cdev->work_flags); } - schedule_work(&led_cdev->set_brightness_work); + queue_work(led_cdev->wq, &led_cdev->set_brightness_work); } EXPORT_SYMBOL_GPL(led_set_brightness_nopm); diff --git a/include/linux/leds.h b/include/linux/leds.h index 6300313c46b7..7c9f1cb12ab9 100644 --- a/include/linux/leds.h +++ b/include/linux/leds.h @@ -169,6 +169,7 @@ struct led_classdev { int new_blink_brightness; void (*flash_resume)(struct led_classdev *led_cdev); + struct workqueue_struct *wq; /* LED workqueue */ struct work_struct set_brightness_work; int delayed_set_value; unsigned long delayed_delay_on;