From patchwork Mon Dec 5 08:04:34 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yang Yingliang X-Patchwork-Id: 29586 Return-Path: Delivered-To: ouuuleilei@gmail.com Received: by 2002:adf:f944:0:0:0:0:0 with SMTP id q4csp2122242wrr; Mon, 5 Dec 2022 00:09:19 -0800 (PST) X-Google-Smtp-Source: AA0mqf6M9jZAA2z914hJGkSiRSBzXXgrUZi2jod8/qX5IkB8+HsGx4C2CX5c25ObiJ/sfM2XN99B X-Received: by 2002:a17:906:6dd7:b0:7a1:1c24:e564 with SMTP id j23-20020a1709066dd700b007a11c24e564mr56601005ejt.629.1670227758879; Mon, 05 Dec 2022 00:09:18 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; t=1670227758; cv=none; d=google.com; s=arc-20160816; b=PZWt9ut/2Q3ioYs6PwFwS7k3B7pvym2/Qie76Tb/+fBvaPZARmOmnmdBx6qr50Mye6 bbvhNyTRVje4CVfeaWRpR+0rgqI3F5gi0kmn5TGf6Z2JcUGpE/fgUKe/4/CMDRZ1Ox/z JcSCa/QlgGQjkOkQQ/olE8iAmKsLssueafdLg+lwFypwZ9oBDeADVrnAyVnxy7un9o5U GcBENh9by5fBOaRV6Tqc3FcpyzF23PfTgbST0VRoM0G1WOsxTKGSMg9WAbh2DChdPs3l edXGxobwKzMGXfLqWgnlRWudkB9MIVv4nTR1E8x7Pz6fH0HyC8N6ypNJ97dAfn0ZlMyH uTDQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:content-transfer-encoding:mime-version :message-id:date:subject:cc:to:from; bh=rmeT5x0DbJY8PbNwbBM3TabWPzmkU2Cl1gHlETVDbLk=; b=l2hdoTvL6hlweDO7A68xN0/my9r5z+XkzGkA3H0RS4fU7PXNYHGfovoHZdR6jtz0Rw Pg7q0iBBR/WtA9Y9NW6Ri+sfJvpPtEXc03T6n3TLcSlm4LjBC8ttA3mPpVTc2+ZSlB6F bDafFwzRgfoH2knrcpKZf9RjZ10772EOnXJmZhUYO0eBXUaG3k4kX1Uf1UJVf/6ElP0E ayi3fNr2xc9RCQzti6nR3ThgiEaPwMy1tnKE2qC9h/AmGi+hRklC3Px6mIqzjXW7oUai ZvyyXrDTDUku7fWztz3JwJFOVgTe6Stn/uvXeHUlRVojV8R3+1JMtbSHW3Js8jJwL93F sJwA== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=fail (p=QUARANTINE sp=QUARANTINE dis=NONE) header.from=huawei.com Received: from out1.vger.email (out1.vger.email. [2620:137:e000::1:20]) by mx.google.com with ESMTP id t4-20020a056402240400b0046c0137c466si8441002eda.293.2022.12.05.00.08.53; Mon, 05 Dec 2022 00:09:18 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=fail (p=QUARANTINE sp=QUARANTINE dis=NONE) header.from=huawei.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231806AbiLEIGt (ORCPT + 99 others); Mon, 5 Dec 2022 03:06:49 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57588 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231393AbiLEIGs (ORCPT ); Mon, 5 Dec 2022 03:06:48 -0500 Received: from szxga02-in.huawei.com (szxga02-in.huawei.com [45.249.212.188]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1DA0C5581 for ; Mon, 5 Dec 2022 00:06:45 -0800 (PST) Received: from dggpemm500007.china.huawei.com (unknown [172.30.72.53]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4NQbhh2yzrzRpmQ; Mon, 5 Dec 2022 16:05:56 +0800 (CST) Received: from huawei.com (10.175.103.91) by dggpemm500007.china.huawei.com (7.185.36.183) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Mon, 5 Dec 2022 16:06:43 +0800 From: Yang Yingliang To: CC: , Subject: [PATCH] w1: fix deadloop in __w1_remove_master_device() Date: Mon, 5 Dec 2022 16:04:34 +0800 Message-ID: <20221205080434.3149205-1-yangyingliang@huawei.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 X-Originating-IP: [10.175.103.91] X-ClientProxiedBy: dggems706-chm.china.huawei.com (10.3.19.183) To dggpemm500007.china.huawei.com (7.185.36.183) X-CFilter-Loop: Reflected X-Spam-Status: No, score=-4.2 required=5.0 tests=BAYES_00,RCVD_IN_DNSWL_MED, SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1751360742269011367?= X-GMAIL-MSGID: =?utf-8?q?1751360742269011367?= I got a deadloop report while doing device(ds2482) add/remove test: [ 162.241881] w1_master_driver w1_bus_master1: Waiting for w1_bus_master1 to become free: refcnt=1. [ 163.272251] w1_master_driver w1_bus_master1: Waiting for w1_bus_master1 to become free: refcnt=1. [ 164.296157] w1_master_driver w1_bus_master1: Waiting for w1_bus_master1 to become free: refcnt=1. ... __w1_remove_master_device() can't return, because the dev->refcnt is not zero. w1_add_master_device() | w1_alloc_dev() | atomic_set(&dev->refcnt, 2) | kthread_run() | |__w1_remove_master_device() | kthread_stop() // KTHREAD_SHOULD_STOP is set, | // threadfn(w1_process) won't be | // called. | kthread() | | // refcnt will never be 0, it's deadloop. | while (atomic_read(&dev->refcnt)) {...} After calling w1_add_master_device(), w1_process() is not really invoked, before w1_process() starting, if kthread_stop() is called in __w1_remove_master_device(), w1_process() will never be called, the refcnt can not be decreased, then it causes deadloop in remove function because of non-zero refcnt. We need to make sure w1_process() is really started, so move the set refcnt into w1_process() to fix this problem. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Yang Yingliang --- drivers/w1/w1.c | 2 ++ drivers/w1/w1_int.c | 5 ++--- 2 files changed, 4 insertions(+), 3 deletions(-) diff --git a/drivers/w1/w1.c b/drivers/w1/w1.c index f2ae2e563dc5..8b35fae4cd61 100644 --- a/drivers/w1/w1.c +++ b/drivers/w1/w1.c @@ -1166,6 +1166,8 @@ int w1_process(void *data) /* remainder if it woke up early */ unsigned long jremain = 0; + atomic_inc(&dev->refcnt); + for (;;) { if (!jremain && dev->search_count) { diff --git a/drivers/w1/w1_int.c b/drivers/w1/w1_int.c index b3e1792d9c49..3a71c5eb2f83 100644 --- a/drivers/w1/w1_int.c +++ b/drivers/w1/w1_int.c @@ -51,10 +51,9 @@ static struct w1_master *w1_alloc_dev(u32 id, int slave_count, int slave_ttl, dev->search_count = w1_search_count; dev->enable_pullup = w1_enable_pullup; - /* 1 for w1_process to decrement - * 1 for __w1_remove_master_device to decrement + /* For __w1_remove_master_device to decrement */ - atomic_set(&dev->refcnt, 2); + atomic_set(&dev->refcnt, 1); INIT_LIST_HEAD(&dev->slist); INIT_LIST_HEAD(&dev->async_list);