From patchwork Wed Apr 12 21:58:53 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Hans de Goede X-Patchwork-Id: 672753 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id C7BF5C77B6C for ; Wed, 12 Apr 2023 21:59:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229535AbjDLV7v (ORCPT ); Wed, 12 Apr 2023 17:59:51 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51124 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229764AbjDLV7u (ORCPT ); Wed, 12 Apr 2023 17:59:50 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4CED459CA for ; Wed, 12 Apr 2023 14:59:08 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1681336747; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=fzNdP8XlgELctBlSSuZSCoWRTxiBD7s45wNhTEtxqXk=; b=Us6n6WTdiBLQqSwd1VpfWVO5YunJaPC+WAJcKlFq80AB8/mr+DXmfcRDLJzYim/Z93ppJ+ PB1wRfXM/bL1t9fTMz58lBXmHE2XTvx2RkdZvaHYqoe67A/0RW7C42SkGPblOSu2MZtNTy aE5d3bKN+K37mThMJ76A+KcbOAtfRms= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-577-nCjSTX3wMESZc9YcmrFnVg-1; Wed, 12 Apr 2023 17:59:04 -0400 X-MC-Unique: nCjSTX3wMESZc9YcmrFnVg-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.rdu2.redhat.com [10.11.54.3]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id D03AE85A588; Wed, 12 Apr 2023 21:59:03 +0000 (UTC) Received: from localhost.localdomain (unknown [10.39.192.14]) by smtp.corp.redhat.com (Postfix) with ESMTP id 1E8731121320; Wed, 12 Apr 2023 21:59:03 +0000 (UTC) From: Hans de Goede To: Pavel Machek , Lee Jones Cc: Hans de Goede , Johannes Berg , linux-leds@vger.kernel.org Subject: [PATCH 2/4] leds: Fix set_brightness_delayed() race Date: Wed, 12 Apr 2023 23:58:53 +0200 Message-Id: <20230412215855.593541-3-hdegoede@redhat.com> In-Reply-To: <20230412215855.593541-1-hdegoede@redhat.com> References: <20230412215855.593541-1-hdegoede@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.3 Precedence: bulk List-ID: X-Mailing-List: linux-leds@vger.kernel.org When a trigger wants to switch from blinking to LED on it needs to call: led_set_brightness(LED_OFF); led_set_brightness(LED_FULL); To first call disables blinking and the second then turns the LED on (the power-supply charging-blink-full-solid triggers do this). These calls happen immediately after each other, so it is possible that set_brightness_delayed() from the first call has not run yet when the led_set_brightness(LED_FULL) call finishes. If this race hits then this is causing problems for both sw- and hw-blinking: For sw-blinking set_brightness_delayed() clears delayed_set_value when LED_BLINK_DISABLE is set causing the led_set_brightness(LED_FULL) call effects to get lost when hitting the race, resulting in the LED turning off instead of on. For hw-blinking if the race hits delayed_set_value has been set to LED_FULL by the time set_brightness_delayed() runs. So led_cdev->brightness_set_blocking() is never called with LED_OFF as argument and the hw-blinking is never disabled leaving the LED blinking instead of on. Fix both issues by adding LED_SET_BRIGHTNESS and LED_SET_BRIGHTNESS_OFF work_flags making this 2 separate actions to be run by set_brightness_delayed(). Signed-off-by: Hans de Goede --- drivers/leds/led-core.c | 57 +++++++++++++++++++++++++++++++---------- include/linux/leds.h | 3 +++ 2 files changed, 47 insertions(+), 13 deletions(-) diff --git a/drivers/leds/led-core.c b/drivers/leds/led-core.c index 4a97cb745788..e61acc785410 100644 --- a/drivers/leds/led-core.c +++ b/drivers/leds/led-core.c @@ -114,21 +114,14 @@ static void led_timer_function(struct timer_list *t) mod_timer(&led_cdev->blink_timer, jiffies + msecs_to_jiffies(delay)); } -static void set_brightness_delayed(struct work_struct *ws) +static void set_brightness_delayed_set_brightness(struct led_classdev *led_cdev, + unsigned int value) { - struct led_classdev *led_cdev = - container_of(ws, struct led_classdev, set_brightness_work); int ret = 0; - if (test_and_clear_bit(LED_BLINK_DISABLE, &led_cdev->work_flags)) { - led_cdev->delayed_set_value = LED_OFF; - led_stop_software_blink(led_cdev); - } - - ret = __led_set_brightness(led_cdev, led_cdev->delayed_set_value); + ret = __led_set_brightness(led_cdev, value); if (ret == -ENOTSUPP) - ret = __led_set_brightness_blocking(led_cdev, - led_cdev->delayed_set_value); + ret = __led_set_brightness_blocking(led_cdev, value); if (ret < 0 && /* LED HW might have been unplugged, therefore don't warn */ !(ret == -ENODEV && (led_cdev->flags & LED_UNREGISTERING) && @@ -137,6 +130,30 @@ static void set_brightness_delayed(struct work_struct *ws) "Setting an LED's brightness failed (%d)\n", ret); } +static void set_brightness_delayed(struct work_struct *ws) +{ + struct led_classdev *led_cdev = + container_of(ws, struct led_classdev, set_brightness_work); + + if (test_and_clear_bit(LED_BLINK_DISABLE, &led_cdev->work_flags)) { + led_stop_software_blink(led_cdev); + set_bit(LED_SET_BRIGHTNESS_OFF, &led_cdev->work_flags); + } + + /* + * Triggers may call led_set_brightness(LED_OFF), + * led_set_brightness(LED_FULL) in quick succession to disable blinking + * and turn the LED on. Both actions may have been scheduled to run + * before this work item runs once. To make sure this works properly + * handle LED_SET_BRIGHTNESS_OFF first. + */ + if (test_and_clear_bit(LED_SET_BRIGHTNESS_OFF, &led_cdev->work_flags)) + set_brightness_delayed_set_brightness(led_cdev, LED_OFF); + + if (test_and_clear_bit(LED_SET_BRIGHTNESS, &led_cdev->work_flags)) + set_brightness_delayed_set_brightness(led_cdev, led_cdev->delayed_set_value); +} + static void led_set_software_blink(struct led_classdev *led_cdev, unsigned long delay_on, unsigned long delay_off) @@ -271,8 +288,22 @@ void led_set_brightness_nopm(struct led_classdev *led_cdev, unsigned int value) if (!__led_set_brightness(led_cdev, value)) return; - /* If brightness setting can sleep, delegate it to a work queue task */ - led_cdev->delayed_set_value = value; + /* + * Brightness setting can sleep, delegate it to a work queue task. + * value 0 / LED_OFF is special, since it also disables hw-blinking + * (sw-blink disable is handled in led_set_brightness()). + * To avoid a hw-blink-disable getting lost when a second brightness + * change is done immediately afterwards (before the work runs), + * it uses a separate work_flag. + */ + if (value) { + led_cdev->delayed_set_value = value; + set_bit(LED_SET_BRIGHTNESS, &led_cdev->work_flags); + } else { + clear_bit(LED_SET_BRIGHTNESS, &led_cdev->work_flags); + set_bit(LED_SET_BRIGHTNESS_OFF, &led_cdev->work_flags); + } + schedule_work(&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 6006786cafdc..eb68aea79c6d 100644 --- a/include/linux/leds.h +++ b/include/linux/leds.h @@ -116,6 +116,9 @@ struct led_classdev { #define LED_BLINK_INVERT 3 #define LED_BLINK_BRIGHTNESS_CHANGE 4 #define LED_BLINK_DISABLE 5 + /* Brightness off also disables hw-blinking so it is a separate action */ +#define LED_SET_BRIGHTNESS_OFF 6 +#define LED_SET_BRIGHTNESS 7 /* Set LED brightness level * Must not sleep. Use brightness_set_blocking for drivers