From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 844A3136337; Tue, 17 Sep 2024 08:04:17 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1726560257; cv=none; b=Iig1bMD9EigciHFk+6jWCUib71yhBoqbIBZVKbMlJdIngI3d0OKVyIeXWc3RGv/CM2/nnpusaXP+cCmiiTQ5bMxvG0jPgMOU+nSqOtK5hx7eJWmHNmVyMc0HBqxPSOvRsmi55nKMEmIuqhdl/+cbA9HCh4jYdA2VfXHIqyXpQBM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1726560257; c=relaxed/simple; bh=qSmOUeitvOYO+X0AQn7LUF4PASe8G186GO/GIZ2AJwo=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=FDYkjtyha2s8PTwWVpYU3acOWLxxorBkmYRpUR3KcjQNObHYfsVg76iQWEvpl9mPNzq6Z/+1u3j3zEH6KrBwnbtCjO9gqyY3IFqVYGnmOTb66Xc/4jOpc+hAnjSHw/oNM6EXA1hsyTAznQ/RXu2QE0sNLHoqUnhdbj9zIUoIF7s= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=ZSwNfkZ0; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="ZSwNfkZ0" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6C36EC4CEC6; Tue, 17 Sep 2024 08:04:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1726560257; bh=qSmOUeitvOYO+X0AQn7LUF4PASe8G186GO/GIZ2AJwo=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=ZSwNfkZ0YxpTjPyDqRgif8IXCSszGvIrkWYIJDgQfFgk/NJKlpV0xZUi1WL8r2S5O sn81g2h2/aBURMG788k4S51y6to7YLtHFFxIHvqMoDKVa+raDoPMUCd0qTVWNdouBR Yo8fX8XFpV4JydaC0uxXpwqcyfUXD8o6VLgZZ3/R8P+M2tKRjiOpfbqMl+SQmKjBCP zBopYgAPd0Q+tfZ/4DTz0hwoQlMDgNfrig2V+vPo1O/wsAa9h/GhBzNuhAdxFqdKbO DgqAoYtUsKm2uwVzuyAmqmrYClHQxLWx1z0aa0SX4GPmgnqa9qHKhnJwGNwTm/whTq SiCNxv4kz3bzg== Date: Tue, 17 Sep 2024 09:04:12 +0100 From: Lee Jones To: Dmitry Rokosov Cc: pavel@ucw.cz, linux-kernel@vger.kernel.org, linux-leds@vger.kernel.org, kernel@salutedevices.com, rockosov@gmail.com, Alexey Romanov Subject: Re: [PATCH v2] leds: introduce ordered workqueue for leds events instead of system_wq Message-ID: <20240917080412.GB9955@google.com> References: <20240903223936.21292-1-ddrokosov@salutedevices.com> <20240916111733.c5rp4l666rtdz7bt@CAB-WSD-L081021> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20240916111733.c5rp4l666rtdz7bt@CAB-WSD-L081021> On Mon, 16 Sep 2024, Dmitry Rokosov wrote: > Hello Lee! > > What are the next steps? Should I make any changes, or are we waiting > for test results from the mailing list members? This is an intrusive core change that was submitted during -rc6. It's going to need some time on the list for people to respond. > Sorry for the ping. > > On Wed, Sep 04, 2024 at 01:39:30AM +0300, 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 > > Signed-off-by: Dmitry Rokosov > > --- > > Changes v2 since v1 at [1]: > > - replace "leds" with "LEDs" in the log message > > > > Links: > > [1] https://lore.kernel.org/all/20240820155407.32729-1-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 c66d1bead0a4..b5e28ad54f7f 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: > > @@ -548,6 +549,8 @@ 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 > > @@ -666,12 +669,19 @@ 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 > > > > -- > Thank you, > Dmitry -- Lee Jones [李琼斯]