From patchwork Sat Jan 28 09:41:45 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Zhong Jinghua X-Patchwork-Id: 648383 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 8D5E6C61DA7 for ; Sat, 28 Jan 2023 09:17:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232579AbjA1JRu (ORCPT ); Sat, 28 Jan 2023 04:17:50 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45224 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230474AbjA1JRt (ORCPT ); Sat, 28 Jan 2023 04:17:49 -0500 Received: from szxga03-in.huawei.com (szxga03-in.huawei.com [45.249.212.189]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D4CDF4EE1; Sat, 28 Jan 2023 01:17:46 -0800 (PST) Received: from kwepemm600002.china.huawei.com (unknown [172.30.72.55]) by szxga03-in.huawei.com (SkyGuard) with ESMTP id 4P3pdV72G9zJqH1; Sat, 28 Jan 2023 17:13:18 +0800 (CST) Received: from localhost.localdomain (10.175.127.227) by kwepemm600002.china.huawei.com (7.193.23.29) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.34; Sat, 28 Jan 2023 17:17:43 +0800 From: Zhong Jinghua To: , , , , , CC: , , , , Subject: [PATCH-next v2 1/2] driver core: introduce get_device_unless_zero() Date: Sat, 28 Jan 2023 17:41:45 +0800 Message-ID: <20230128094146.205858-2-zhongjinghua@huawei.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20230128094146.205858-1-zhongjinghua@huawei.com> References: <20230128094146.205858-1-zhongjinghua@huawei.com> MIME-Version: 1.0 X-Originating-IP: [10.175.127.227] X-ClientProxiedBy: dggems702-chm.china.huawei.com (10.3.19.179) To kwepemm600002.china.huawei.com (7.193.23.29) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-scsi@vger.kernel.org When the dev reference count is 0, calling get_device will go from 0 to 1, which will cause errors in some place of the kernel. So introduce a get_devcie_unless_zero method that returns NULL when the dev reference count is 0. Signed-off-by: Zhong Jinghua --- drivers/base/core.c | 8 ++++++++ include/linux/device.h | 1 + 2 files changed, 9 insertions(+) diff --git a/drivers/base/core.c b/drivers/base/core.c index d02501933467..6f17a93a3443 100644 --- a/drivers/base/core.c +++ b/drivers/base/core.c @@ -3613,6 +3613,14 @@ struct device *get_device(struct device *dev) } EXPORT_SYMBOL_GPL(get_device); +struct device __must_check *get_device_unless_zero(struct device *dev) +{ + if (!dev || !kobject_get_unless_zero(&dev->kobj)) + return NULL; + return dev; +} +EXPORT_SYMBOL_GPL(get_device_unless_zero); + /** * put_device - decrement reference count. * @dev: device in question. diff --git a/include/linux/device.h b/include/linux/device.h index 424b55df0272..c63bac6d51c8 100644 --- a/include/linux/device.h +++ b/include/linux/device.h @@ -1069,6 +1069,7 @@ extern int (*platform_notify_remove)(struct device *dev); * */ struct device *get_device(struct device *dev); +struct device __must_check *get_device_unless_zero(struct device *dev); void put_device(struct device *dev); bool kill_device(struct device *dev);