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 D364CC433B4 for ; Mon, 17 May 2021 12:34:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A53276124C for ; Mon, 17 May 2021 12:34:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235233AbhEQMfr (ORCPT ); Mon, 17 May 2021 08:35:47 -0400 Received: from szxga05-in.huawei.com ([45.249.212.191]:3570 "EHLO szxga05-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229734AbhEQMfq (ORCPT ); Mon, 17 May 2021 08:35:46 -0400 Received: from dggems701-chm.china.huawei.com (unknown [172.30.72.59]) by szxga05-in.huawei.com (SkyGuard) with ESMTP id 4FkJQz44xFzmVW4; Mon, 17 May 2021 20:31:39 +0800 (CST) Received: from dggema762-chm.china.huawei.com (10.1.198.204) by dggems701-chm.china.huawei.com (10.3.19.178) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256) id 15.1.2176.2; Mon, 17 May 2021 20:34:21 +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; Mon, 17 May 2021 20:34:20 +0800 Subject: Re: [PATCH] drm: bridge: cdns-mhdp8546: Fix PM reference leak in cdns_mhdp_probe() To: Robert Foss 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: Mon, 17 May 2021 20:34:20 +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: dggems705-chm.china.huawei.com (10.3.19.182) 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 On 2021/05/17 17:27, 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"); >> 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]. > > [1] https://elixir.bootlin.com/linux/latest/source/include/linux/pm_runtime.h#L384 > [2] https://elixir.bootlin.com/linux/latest/source/drivers/base/power/runtime.c#L1383 > . > Hi, Thank you very much for your explanation Yu Kuai