From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from szxga07-in.huawei.com (szxga07-in.huawei.com [45.249.212.35]) (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 258231B1D59; Wed, 21 Aug 2024 11:22:58 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.35 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1724239383; cv=none; b=ZjD2H0OHkbSkuqCZg7pJgle6sMRivU4huYLa3MSA+hB44wFSRwA+hDgQHWF//nsy0cPtG/ZnDM4LpjLeC/EdD0dOqopeniwXJc7zgB2azoPdZUN3tUh4RTEhv0g7Jq560F7zrSfVRlpOkCQ+ZzOZWvPkePrSsj6mW+tuxuQrIgA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1724239383; c=relaxed/simple; bh=Hdmp5u6r2ZCBG5/1/JMr2LDYkecTKqDHT17FSeTqD0E=; h=Message-ID:Date:MIME-Version:Subject:To:CC:References:From: In-Reply-To:Content-Type; b=blSmfGYJO3a+z0qfl3+IQKxWZBHutdKSOcnJHPxqD5MlRLlxk3KMNvajTrdB61dSkXYuyDSd8KFBy2jCSI0s9KO7e2vkL6+3F9NUBs6g6HNth3IfkgbiP5ONzx3n89pewWp1ikkXLC2aq9Sb1AAx/6uBgtus6vtO4t5HvNaRXlg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com; spf=pass smtp.mailfrom=huawei.com; arc=none smtp.client-ip=45.249.212.35 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huawei.com Received: from mail.maildlp.com (unknown [172.19.163.44]) by szxga07-in.huawei.com (SkyGuard) with ESMTP id 4WpkTS68F5z1S8Pn; Wed, 21 Aug 2024 19:22:52 +0800 (CST) Received: from kwepemm600004.china.huawei.com (unknown [7.193.23.242]) by mail.maildlp.com (Postfix) with ESMTPS id C016F1400C9; Wed, 21 Aug 2024 19:22:55 +0800 (CST) Received: from [10.67.121.59] (10.67.121.59) by kwepemm600004.china.huawei.com (7.193.23.242) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.1.2507.39; Wed, 21 Aug 2024 19:22:55 +0800 Message-ID: Date: Wed, 21 Aug 2024 19:22:54 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.2.0 Subject: Re: [PATCH v3 02/14] thermal: core: Rearrange checks in thermal_bind_cdev_to_trip() To: Daniel Lezcano , "Rafael J. Wysocki" CC: LKML , Lukasz Luba , Zhang Rui , Linux PM References: <2205737.irdbgypaU6@rjwysocki.net> <3324214.44csPzL39Z@rjwysocki.net> <68ed6185-a602-c0fc-721e-b5d68fea83f8@huawei.com> <66bb19a0-00ba-40a5-91ef-73368659b30a@linaro.org> <8744a789-0424-0cc6-7cb1-b7c9b17f56cc@huawei.com> From: "lihuisong (C)" In-Reply-To: Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit X-ClientProxiedBy: dggems702-chm.china.huawei.com (10.3.19.179) To kwepemm600004.china.huawei.com (7.193.23.242) 在 2024/8/21 18:49, Daniel Lezcano 写道: > On 21/08/2024 11:44, lihuisong (C) wrote: >> >> 在 2024/8/21 17:28, Daniel Lezcano 写道: >>> On 21/08/2024 10:49, lihuisong (C) wrote: >>> >>> [ ... ] >>> >>>>> -    list_for_each_entry(pos2, &thermal_cdev_list, node) { >>>>> -        if (pos2 == cdev) >>>>> -            break; >>>>> -    } >>>>> +    lockdep_assert_held(&thermal_list_lock); >>>>> -    if (tz != pos1 || cdev != pos2) >>>>> +    if (list_empty(&tz->node) || list_empty(&cdev->node)) >>>> The old verification is ensure that tz and cdev already add to >>>> thermal_tz_list and thermal_cdev_list，respectively. >>>> Namely, tz and cdev are definitely registered and intialized. >>>> The check is ok for all untizalized thermal_zone_device and cooling >>>> device. >>>> But the new verification doesn't seem to do that. >>> >>> If the tz or the cdev are registered then their "->node" is not >>> empty because they are linked with the thermal_list and cdev_list >>> >>> So either way is browsing the lists to find the tz/cdev or just >>> check "->node" is not empty. The latter the faster. >> Assume that tz/cdev isn't intiazlized and registered to >> thermal_tz_list or thermal_cdev_list. And then directly call this >> interface. > > Then there is a bug in the internal code because the > thermal_zone_device_register*() and cooling_device_device_register() > allocate and initialize those structures. > > The caller of the function is supposed to use the API provided by the > thermal framework. It is not possible to plan every stupid things a > driver can do. In this particular case, very likely the kernel will > crash immediately which is a sufficient test for me and coercive > enough to have the API user to put its code in question ;) A good point. Agree.