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=-16.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 8DA29C47098 for ; Thu, 3 Jun 2021 11:09:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7B3D4613D7 for ; Thu, 3 Jun 2021 11:09:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229976AbhFCLK5 (ORCPT ); Thu, 3 Jun 2021 07:10:57 -0400 Received: from mail.kernel.org ([198.145.29.99]:34106 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229982AbhFCLK4 (ORCPT ); Thu, 3 Jun 2021 07:10:56 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 6B771613DC; Thu, 3 Jun 2021 11:09:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1622718552; bh=oulCTMRij/0YKDHZtxJlmXnKJmrq738g2Nu5+8hJZhk=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=uEQn0pJD1PpIW/izJTVru84b4xULfY30cOgBeXGpgSr7q5q89Jf33lpwgdwsqXLlT biDKRwbm7WED7jPvms1Cyc5RgvtroAhrGbmW7f8W7pHWmgm97ATjGqDbGyWeG4UImp l2zOPwL9yFJYCiUrmaSCutPVRLYtpU2MetnIHIJ/4bEmM2qvbCf3l3kI1xvDTnLi8P jPQh+3lQ6ap43tRTp5K+DPtNPGiPa2l6axks1L42ELpdYspCMnQZqVtgz8sDgbFXFY j9cnekwJbpza7J93CZaPTIwHmIq/IEtOltSu61nImCQcYJKQKwvo8WrZhGCYEIm2FA tdGFp450SBXdg== Date: Thu, 3 Jun 2021 16:39:08 +0530 From: Vinod Koul To: Johan Hovold Cc: "yukuai (C)" , mcoquelin.stm32@gmail.com, alexandre.torgue@foss.st.com, michal.simek@xilinx.com, dmaengine@vger.kernel.org, linux-kernel@vger.kernel.org, linux-stm32@st-md-mailman.stormreply.com, linux-arm-kernel@lists.infradead.org, yi.zhang@huawei.com Subject: Re: [PATCH 2/3] dmaengine: usb-dmac: Fix PM reference leak in usb_dmac_probe() Message-ID: References: <20210517081826.1564698-1-yukuai3@huawei.com> <20210517081826.1564698-3-yukuai3@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: dmaengine@vger.kernel.org On 31-05-21, 11:19, Johan Hovold wrote: > On Mon, May 31, 2021 at 02:27:34PM +0530, Vinod Koul wrote: > > On 31-05-21, 14:11, yukuai (C) wrote: > > > On 2021/05/31 12:00, Vinod Koul wrote: > > > > On 17-05-21, 16:18, 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/dma/sh/usb-dmac.c | 2 +- > > > > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > > > > > > > diff --git a/drivers/dma/sh/usb-dmac.c b/drivers/dma/sh/usb-dmac.c > > > > > index 8f7ceb698226..2a6c8fd8854e 100644 > > > > > --- a/drivers/dma/sh/usb-dmac.c > > > > > +++ b/drivers/dma/sh/usb-dmac.c > > > > > @@ -796,7 +796,7 @@ static int usb_dmac_probe(struct platform_device *pdev) > > > > > /* Enable runtime PM and initialize the device. */ > > > > > pm_runtime_enable(&pdev->dev); > > > > > - ret = pm_runtime_get_sync(&pdev->dev); > > > > > + ret = pm_runtime_resume_and_get(&pdev->dev); > > > > > > > > This does not seem to fix anything.. the below goto goes and disables > > > > the runtime_pm for this device and thus there wont be any leak > > > Hi, > > > > > > If pm_runtime_get_sync() fails and increments the pm.usage_count > > > variable, pm_runtime_disable() does not reset the counter, and > > > we still need to decrement the usage count when pm_runtime_get_sync() > > > fails. Do I miss anthing? > > > > Yes the rumtime_pm is disabled on failure here and the count would have > > no consequence... > > You should still balance the PM usage counter as it isn't reset for > example when reloading the driver. Should I driver trust that on load PM usage counter is balanced and not to be reset..? > Using pm_runtime_resume_and_get() is one way of handling this, but > alternatively you could also move the error_pm label above the > pm_runtime_put() in the error path. That would be a better way I think -- ~Vinod