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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 02901ECAAD2 for ; Sat, 27 Aug 2022 09:29:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230427AbiH0J3l (ORCPT ); Sat, 27 Aug 2022 05:29:41 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45458 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230176AbiH0J3k (ORCPT ); Sat, 27 Aug 2022 05:29:40 -0400 Received: from szxga03-in.huawei.com (szxga03-in.huawei.com [45.249.212.189]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 467E131341; Sat, 27 Aug 2022 02:29:38 -0700 (PDT) Received: from dggpemm500020.china.huawei.com (unknown [172.30.72.54]) by szxga03-in.huawei.com (SkyGuard) with ESMTP id 4MFBFP2mrmzGpGr; Sat, 27 Aug 2022 17:27:53 +0800 (CST) Received: from dggpemm500007.china.huawei.com (7.185.36.183) by dggpemm500020.china.huawei.com (7.185.36.49) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Sat, 27 Aug 2022 17:29:36 +0800 Received: from [10.174.178.174] (10.174.178.174) 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 15.1.2375.24; Sat, 27 Aug 2022 17:29:35 +0800 Subject: Re: [PATCH -next 2/3] PCI: fix possible memory leak in error case in pci_register_host_bridge() To: Bjorn Helgaas CC: , , , Arnd Bergmann , Rob Herring References: <20220826223810.GA2961041@bhelgaas> From: Yang Yingliang Message-ID: <83f42399-6dc3-d227-bb48-891172e061f9@huawei.com> Date: Sat, 27 Aug 2022 17:29:35 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 MIME-Version: 1.0 In-Reply-To: <20220826223810.GA2961041@bhelgaas> Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US X-Originating-IP: [10.174.178.174] X-ClientProxiedBy: dggems704-chm.china.huawei.com (10.3.19.181) To dggpemm500007.china.huawei.com (7.185.36.183) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org On 2022/8/27 6:38, Bjorn Helgaas wrote: > [+cc Arnd, Rob] > > On Thu, Aug 25, 2022 at 08:27:52PM +0800, Yang Yingliang wrote: >> If device_register() fails in pci_register_host_bridge(), the refcount >> of bus device is leaked, so device name that set by dev_set_name() can >> not be freed. Fix this by calling put_device() when device_register() >> fails, so the device name will be freed in kobject_cleanup(). >> >> Fixes: 37d6a0a6f470 ("PCI: Add pci_register_host_bridge() interface") >> Signed-off-by: Yang Yingliang >> --- >> drivers/pci/probe.c | 17 +++++++++++------ >> 1 file changed, 11 insertions(+), 6 deletions(-) >> >> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c >> index e500eb9d6468..292d9da146ce 100644 >> --- a/drivers/pci/probe.c >> +++ b/drivers/pci/probe.c >> @@ -948,8 +948,17 @@ static int pci_register_host_bridge(struct pci_host_bridge *bridge) >> name = dev_name(&bus->dev); >> >> err = device_register(&bus->dev); >> - if (err) >> - goto unregister; >> + if (err) { >> + /* >> + * release_pcibus_dev() will decrease the refcount of bridge >> + * device and free the memory of bus. >> + * The memory of bus device name will be freed when the refcount >> + * get to zero. >> + */ >> + put_device(&bus->dev); >> + device_unregister(&bridge->dev); >> + return err; >> + } > Calling put_device(X) after device_register(X) returns failure doesn't > need explanation because that's the standard pattern. I think that > was just missing before. > > In this error case, we previously did called put_device() for the > *bridge* instead of the bus. That was likely a typo and seems like > the important thing here. put_device() for the bridge will be called in the callback of put for the bus. So it doesn't call put bridge device here. Thanks, Yang >> pcibios_add_bus(bus); >> >> @@ -1025,10 +1034,6 @@ static int pci_register_host_bridge(struct pci_host_bridge *bridge) >> >> return 0; >> >> -unregister: >> - put_device(&bridge->dev); >> - device_unregister(&bridge->dev); >> - >> free: >> kfree(bus); >> return err; >> -- >> 2.25.1 >> > .