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=-15.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=ham 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 6C9FDC47082 for ; Sat, 29 May 2021 09:15:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 49E83611AC for ; Sat, 29 May 2021 09:15:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229775AbhE2JQ7 (ORCPT ); Sat, 29 May 2021 05:16:59 -0400 Received: from szxga01-in.huawei.com ([45.249.212.187]:2092 "EHLO szxga01-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229738AbhE2JQ7 (ORCPT ); Sat, 29 May 2021 05:16:59 -0400 Received: from dggemv704-chm.china.huawei.com (unknown [172.30.72.55]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4FsbPb5jSXzWnhQ; Sat, 29 May 2021 17:10:43 +0800 (CST) Received: from dggema762-chm.china.huawei.com (10.1.198.204) by dggemv704-chm.china.huawei.com (10.3.19.47) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256) id 15.1.2176.2; Sat, 29 May 2021 17:15:21 +0800 Received: from [10.174.179.129] (10.174.179.129) by dggema762-chm.china.huawei.com (10.1.198.204) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.2176.2; Sat, 29 May 2021 17:15:20 +0800 Subject: Re: [PATCH] drm: bridge: cdns-mhdp8546: Fix PM reference leak in cdns_mhdp_probe() To: Robert Foss , Johan Hovold CC: Andrzej Hajda , Neil Armstrong , David Airlie , Daniel Vetter , dri-devel , linux-kernel , References: <20210517081601.1563193-1-yukuai3@huawei.com> From: "yukuai (C)" Message-ID: Date: Sat, 29 May 2021 17:15:20 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [10.174.179.129] X-ClientProxiedBy: dggems704-chm.china.huawei.com (10.3.19.181) To dggema762-chm.china.huawei.com (10.1.198.204) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org ping ... On 2021/05/18 20:58, Robert Foss wrote: > On Tue, 18 May 2021 at 09:42, Johan Hovold wrote: >> >> On Mon, May 17, 2021 at 11:27:38AM +0200, Robert Foss wrote: >>> Hey Yu, >>> >>> On Mon, 17 May 2021 at 10:08, Yu Kuai wrote: >>>> >>>> pm_runtime_get_sync will increment pm usage counter even it failed. >>>> Forgetting to putting operation will result in reference leak here. >>>> Fix it by replacing it with pm_runtime_resume_and_get to keep usage >>>> counter balanced. >>>> >>>> Reported-by: Hulk Robot >>>> Signed-off-by: Yu Kuai >>>> --- >>>> drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c | 2 +- >>>> 1 file changed, 1 insertion(+), 1 deletion(-) >>>> >>>> diff --git a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c >>>> index 0cd8f40fb690..305489d48c16 100644 >>>> --- a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c >>>> +++ b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c >>>> @@ -2478,7 +2478,7 @@ static int cdns_mhdp_probe(struct platform_device *pdev) >>>> clk_prepare_enable(clk); >>>> >>>> pm_runtime_enable(dev); >>>> - ret = pm_runtime_get_sync(dev); >>>> + ret = pm_runtime_resume_and_get(dev); >>>> if (ret < 0) { >>>> dev_err(dev, "pm_runtime_get_sync failed\n"); > > This error message is a bit confusing now, could you update it. > >>>> pm_runtime_disable(dev); >>> >>> The code is correct as it is. If pm_runtime_get_sync() fails and >>> increments[1] the pm.usage_count variable, that isn't a problem since >>> pm_runtime_disable() disables pm, and resets pm.usage_count variable >>> to zero[2]. >> >> No it doesn't; pm_runtime_disable() does not reset the counter and you >> still need to decrement the usage count when pm_runtime_get_sync() >> fails. > > Thanks for chiming in Johan, you're absolutely right and I must have > misread something. > > With the above fix, feel free to add my r-b. > > Reviewed-by: Robert Foss > . >