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=-15.2 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 23B4CC2D0E4 for ; Fri, 27 Nov 2020 10:06:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C5BBF21D93 for ; Fri, 27 Nov 2020 10:06:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728792AbgK0KGZ (ORCPT ); Fri, 27 Nov 2020 05:06:25 -0500 Received: from foss.arm.com ([217.140.110.172]:36722 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726202AbgK0KGZ (ORCPT ); Fri, 27 Nov 2020 05:06:25 -0500 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 4293C1516; Fri, 27 Nov 2020 02:06:24 -0800 (PST) Received: from [192.168.1.179] (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 2F2D93F71F; Fri, 27 Nov 2020 02:06:23 -0800 (PST) Subject: Re: [PATCH] drm/panfrost: fix reference leak in panfrost_job_hw_submit To: Qinglang Miao , Rob Herring , Tomeu Vizoso , Alyssa Rosenzweig , David Airlie , Daniel Vetter Cc: dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org References: <20201127094441.121094-1-miaoqinglang@huawei.com> From: Steven Price Message-ID: <46d1944e-fbbe-075f-1c5b-356b5ce73ee0@arm.com> Date: Fri, 27 Nov 2020 10:06:11 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20201127094441.121094-1-miaoqinglang@huawei.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-GB Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 27/11/2020 09:44, Qinglang Miao wrote: > pm_runtime_get_sync will increment pm usage counter even it > failed. Forgetting to putting operation will result in a > reference leak here. > > A new function pm_runtime_resume_and_get is introduced in > [0] to keep usage counter balanced. So We fix the reference > leak by replacing it with new funtion. > > [0] dd8088d5a896 ("PM: runtime: Add pm_runtime_resume_and_get to deal with usage counter") > > Fixes: f3ba91228e8e ("drm/panfrost: Add initial panfrost driver") > Reported-by: Hulk Robot > Signed-off-by: Qinglang Miao > --- > drivers/gpu/drm/panfrost/panfrost_job.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/panfrost/panfrost_job.c b/drivers/gpu/drm/panfrost/panfrost_job.c > index 30e7b7196..04cf3bb67 100644 > --- a/drivers/gpu/drm/panfrost/panfrost_job.c > +++ b/drivers/gpu/drm/panfrost/panfrost_job.c > @@ -147,7 +147,7 @@ static void panfrost_job_hw_submit(struct panfrost_job *job, int js) > > panfrost_devfreq_record_busy(&pfdev->pfdevfreq); > > - ret = pm_runtime_get_sync(pfdev->dev); > + ret = pm_runtime_resume_and_get(pfdev->dev); Sorry, but in this case this change isn't correct. panfrost_job_hw_submit() is expected to be unbalanced (the PM reference count is expected to be incremented on return). In the case where pm_runtime_get_sync() fails, the job will eventually timeout, and there's a corresponding pm_runtime_put_noidle() in panfrost_reset(). Potentially this could be handled better (e.g. without waiting for the timeout to occur), but equally this isn't something we expect to happen in normal operation). Steve > if (ret < 0) > return; > >