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 BD2B9C282CE for ; Wed, 22 May 2019 20:02:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8B27F20856 for ; Wed, 22 May 2019 20:02:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1558555338; bh=5NdB2/oVoctYoT1f+lKCXQgAtRDIr4XP3VOrre8ZM2M=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=CVRDQjyxQ2U4Hnqxuzswq6JPNdBkWrTvzIlB06xYad5lRMfhNqJzyo1ol9Bynxb0E iE3HPln/XjE7JopRx9DCBz95fQboXME+BB/kUsJVUoIXy9xMznamWu00KsMHC4ov1Y ObCohrMs0Y2V/LsXu1dTzZfdEkb7NKSqZ3cmRP2o= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730996AbfEVUCR (ORCPT ); Wed, 22 May 2019 16:02:17 -0400 Received: from mail.kernel.org ([198.145.29.99]:42768 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730278AbfEVTWF (ORCPT ); Wed, 22 May 2019 15:22:05 -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 5C012217F9; Wed, 22 May 2019 19:22:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1558552925; bh=5NdB2/oVoctYoT1f+lKCXQgAtRDIr4XP3VOrre8ZM2M=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=JgE55VfTTH+4qLsR1UjJakOznfVnJBTLpSMx7KBD0ixnXFvN+pxhsyLjd8+rO9/GW EGZ05Q9oA/1wq5KukvNqn7fgrLYwCJTWtW/x4aYWtv1++cNoLHiDc8wmaUdgEnvuLn CP1RK/G1NKauqNtskD7zmeFnRnLpxy0TNpc6fHww= 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 5.1 033/375] leds: avoid races with workqueue Date: Wed, 22 May 2019 15:15:33 -0400 Message-Id: <20190522192115.22666-33-sashal@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190522192115.22666-1-sashal@kernel.org> References: <20190522192115.22666-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@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 e3da7c03da1b5..e9ae7f87ab900 100644 --- a/drivers/leds/led-core.c +++ b/drivers/leds/led-core.c @@ -164,6 +164,11 @@ 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