From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4684FC282CE for ; Wed, 22 May 2019 19:49:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 15E4A20862 for ; Wed, 22 May 2019 19:49:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1558554555; bh=olLlbsdVvG3O0pmW/Xs7F+gvHtWBPuONA/cLfOxDLcQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=iy2xzWju4fw8Biiuyid0qY2EP6NRwDd3mKDyE9/3hGzrJyfnaUbZT+8t3BANqfZ0l RNTkgx4Y3CF4ph15f+CW2MnfvVW+MWRitChKPcXHTSLkk7ZDkDDT5j0Xtwt06T2huU RlGATzt9ddlfr7/PKiAvN44/dVfpDjywSk5GRl3w= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729991AbfEVT1C (ORCPT ); Wed, 22 May 2019 15:27:02 -0400 Received: from mail.kernel.org ([198.145.29.99]:48790 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732215AbfEVT1C (ORCPT ); Wed, 22 May 2019 15:27:02 -0400 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 7288621841; Wed, 22 May 2019 19:27:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1558553221; bh=olLlbsdVvG3O0pmW/Xs7F+gvHtWBPuONA/cLfOxDLcQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=UBqF1TuQRPTvJuHV2y/ToLYPrU0Yg8qedkRNrEW1bBclLlGaTd5yujfivJhlyTUXl IA3IYz6GWyJKAYzDxxZKl9pbKjFG7SLjYRpG26u79CUuO7uJ1Y0KEHYtn/XFej+YxD OpZV88S9UfBc74an5q4Q1i3MQOqJAesKoD3kYBmM= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Pavel Machek , Jacek Anaszewski , Sasha Levin , linux-leds@vger.kernel.org Subject: [PATCH AUTOSEL 4.19 021/244] leds: avoid races with workqueue Date: Wed, 22 May 2019 15:22:47 -0400 Message-Id: <20190522192630.24917-21-sashal@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190522192630.24917-1-sashal@kernel.org> References: <20190522192630.24917-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Pavel Machek [ Upstream commit 0db37915d912e8dc6588f25da76d3ed36718d92f ] There are races between "main" thread and workqueue. They manifest themselves on Thinkpad X60: This should result in LED blinking, but it turns it off instead: root@amd:/data/pavel# cd /sys/class/leds/tpacpi\:\:power root@amd:/sys/class/leds/tpacpi::power# echo timer > trigger root@amd:/sys/class/leds/tpacpi::power# echo timer > trigger It should be possible to transition from blinking to solid on by echo 0 > brightness; echo 1 > brightness... but that does not work, either, if done too quickly. Synchronization of the workqueue fixes both. Fixes: 1afcadfcd184 ("leds: core: Use set_brightness_work for the blocking op") Signed-off-by: Pavel Machek Signed-off-by: Jacek Anaszewski Signed-off-by: Sasha Levin --- drivers/leds/led-class.c | 1 + drivers/leds/led-core.c | 5 +++++ 2 files changed, 6 insertions(+) diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c index 3c7e3487b373b..85848c5da705f 100644 --- a/drivers/leds/led-class.c +++ b/drivers/leds/led-class.c @@ -57,6 +57,7 @@ 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: diff --git a/drivers/leds/led-core.c b/drivers/leds/led-core.c index ede4fa0ac2cce..55dec67023599 100644 --- a/drivers/leds/led-core.c +++ b/drivers/leds/led-core.c @@ -162,6 +162,11 @@ static void led_blink_setup(struct led_classdev *led_cdev, unsigned long *delay_on, unsigned long *delay_off) { + /* + * If "set brightness to 0" is pending in workqueue, we don't + * want that to be reordered after blink_set() + */ + flush_work(&led_cdev->set_brightness_work); if (!test_bit(LED_BLINK_ONESHOT, &led_cdev->work_flags) && led_cdev->blink_set && !led_cdev->blink_set(led_cdev, delay_on, delay_off)) -- 2.20.1