From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <SRS0=pNjS=57=vger.kernel.org=linux-kernel-owner@kernel.org>
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=-2.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED,
	DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,
	SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 670E2C2BA19
	for <linux-kernel@archiver.kernel.org>; Wed, 15 Apr 2020 23:28:54 +0000 (UTC)
Received: from vger.kernel.org (vger.kernel.org [23.128.96.18])
	by mail.kernel.org (Postfix) with ESMTP id 4542A20732
	for <linux-kernel@archiver.kernel.org>; Wed, 15 Apr 2020 23:28:54 +0000 (UTC)
Authentication-Results: mail.kernel.org;
	dkim=pass (2048-bit key) header.d=nvidia.com header.i=@nvidia.com header.b="B7RqrbPG"
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
        id S2389436AbgDOX2x (ORCPT
        <rfc822;linux-kernel@archiver.kernel.org>);
        Wed, 15 Apr 2020 19:28:53 -0400
Received: from hqnvemgate26.nvidia.com ([216.228.121.65]:3970 "EHLO
        hqnvemgate26.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
        with ESMTP id S2389251AbgDOX2r (ORCPT
        <rfc822;linux-kernel@vger.kernel.org>);
        Wed, 15 Apr 2020 19:28:47 -0400
Received: from hqpgpgate101.nvidia.com (Not Verified[216.228.121.13]) by hqnvemgate26.nvidia.com (using TLS: TLSv1.2, DES-CBC3-SHA)
        id <B5e9798a00000>; Wed, 15 Apr 2020 16:28:32 -0700
Received: from hqmail.nvidia.com ([172.20.161.6])
  by hqpgpgate101.nvidia.com (PGP Universal service);
  Wed, 15 Apr 2020 16:28:45 -0700
X-PGP-Universal: processed;
        by hqpgpgate101.nvidia.com on Wed, 15 Apr 2020 16:28:45 -0700
Received: from DRHQMAIL107.nvidia.com (10.27.9.16) by HQMAIL111.nvidia.com
 (172.20.187.18) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Wed, 15 Apr
 2020 23:28:44 +0000
Received: from [10.2.171.241] (10.124.1.5) by DRHQMAIL107.nvidia.com
 (10.27.9.16) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Wed, 15 Apr
 2020 23:28:43 +0000
Subject: Re: [RFC PATCH v7 6/9] media: tegra: Add Tegra210 Video input driver
From:   Sowjanya Komatineni <skomatineni@nvidia.com>
To:     Dmitry Osipenko <digetx@gmail.com>
CC:     <thierry.reding@gmail.com>, <jonathanh@nvidia.com>,
        <frankc@nvidia.com>, <hverkuil@xs4all.nl>, <sakari.ailus@iki.fi>,
        <helen.koike@collabora.com>, <sboyd@kernel.org>,
        <linux-media@vger.kernel.org>, <devicetree@vger.kernel.org>,
        <linux-clk@vger.kernel.org>, <linux-tegra@vger.kernel.org>,
        <linux-kernel@vger.kernel.org>
References: <1586919463-30542-1-git-send-email-skomatineni@nvidia.com>
 <1586919463-30542-7-git-send-email-skomatineni@nvidia.com>
 <4118112f-f865-5460-6319-d71271fd78d1@gmail.com>
 <a69a8b34-beea-3ad0-e08e-f7df8b9e7047@nvidia.com>
 <6afa951e-d904-f3c0-053f-82a02fb18979@nvidia.com>
 <b1c78827-13ea-0c94-a575-97b5afc0ede1@nvidia.com>
 <5954a7e1-910e-7f48-56d3-e671b56ead74@nvidia.com>
 <d6a9e07c-474a-a076-8313-32f5f4ca8d64@nvidia.com>
 <786949a9-8507-7723-f29b-b91a216bfd28@nvidia.com>
 <f831408b-bbf4-3047-20e3-5bebfa9fc1ad@gmail.com>
 <2ad9352f-cb65-1643-e540-a21f9c570266@nvidia.com>
 <31924f2b-8f85-d28d-4f5d-4e232bff94a5@nvidia.com>
Message-ID: <c95cd2b6-8036-8c0a-25f3-6ea3fe35334a@nvidia.com>
Date:   Wed, 15 Apr 2020 16:28:42 -0700
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101
 Thunderbird/60.9.0
MIME-Version: 1.0
In-Reply-To: <31924f2b-8f85-d28d-4f5d-4e232bff94a5@nvidia.com>
X-Originating-IP: [10.124.1.5]
X-ClientProxiedBy: HQMAIL105.nvidia.com (172.20.187.12) To
 DRHQMAIL107.nvidia.com (10.27.9.16)
Content-Type: text/plain; charset="utf-8"; format=flowed
Content-Transfer-Encoding: quoted-printable
Content-Language: en-US
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nvidia.com; s=n1;
        t=1586993312; bh=ICREte8mX5YUPIFrhY1710Iw4rpBoVPzTv3ozhTn9IQ=;
        h=X-PGP-Universal:Subject:From:To:CC:References:Message-ID:Date:
         User-Agent:MIME-Version:In-Reply-To:X-Originating-IP:
         X-ClientProxiedBy:Content-Type:Content-Transfer-Encoding:
         Content-Language;
        b=B7RqrbPG3SxfbK/LMSLj3LRx5OE7G4VnGv/9K9BbpYBLlc/c02latfD7klMQQPpsW
         DmK2qBDQKXnxZJaj2iBMOIwxaoouNqh9xnFAPa3t++oo3qFYKg7yCbiNFtFZInI6vV
         86Pu5hHJwoW3NyGu4pUHDdZ3YqsjGuaz/WevEHFlh/FYN8W4UMSsO7cd6YORRROL1C
         umfret7nuupHVgHkJzBEO/wbs6cE819Nips86flhMuaDD2E3wdXYjNpEFk1+cdTPG0
         0Xn6EHqr+5WbRkj8XtpqiniD3lXxL/cckKNArjHhx4Yd1WiTCrDBHffmFUBPODdPXN
         fMIj6L5A/Hh3A==
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

Sorry please ignore.

We can't free vi during v4l2 device release as when no device nodes are=20
opened, vi free happens right away during host1x_video_remove.

With this tegra-video driver unbind ->bind will not work as vi memory=20
allocated during vi_probe gets freed during v4l2 device release so=20
during bind init() callback execution will crash as vi got freed while=20
vi driver is still bound to device.

Will wait for Hans/Thierry comments as I see dependency depending on=20
where unbind/bind happens.


On 4/15/20 4:08 PM, Sowjanya Komatineni wrote:
> With minor change of not using vi reference after=20
> host1x_client_unregister and freeing vi during v4l2 device release works.
>
> For csi, we can use devm_kzalloc for now untill we decide later if we=20
> want to expose async subdev nodes during sensor support.
>
> Will have this fix in v8 with a comment in vi_remove to make sure not=20
> to use vi reference after host1x_client_unregister.
>
> Will test more and will release v8 with above fix to allow direct=20
> host1x client driver unbind.
>
> Thanks
>
> sowjanya
>
>
> On 4/15/20 12:51 PM, Sowjanya Komatineni wrote:
>>
>> On 4/15/20 12:21 PM, Dmitry Osipenko wrote:
>>> External email: Use caution opening links or attachments
>>>
>>>
>>> 15.04.2020 21:53, Sowjanya Komatineni =D0=BF=D0=B8=D1=88=D0=B5=D1=82:
>>> ...
>>>>>>>>>> Have you tried to test this driver under KASAN? I suspect that
>>>>>>>>>> you just
>>>>>>>>>> masked the problem, instead of fixing it.
>>>> Tested with kmemleak scan and did not see any memory leaks
>>> You should get use-after-free and not memleak.
>> I don't see use-after-free bugs during the testing.
>>
>> But as mentioned when direct vi/csi client driver unbind happens=20
>> while video device node is kept opened, vi driver remove will free vi=20
>> structure memory but actual video device memory which is part of=20
>> channels remains but list head gets lost when vi structure is freed.
>>
>> So, when device node is released and executes release callback as=20
>> list head is lost it can't free allocated channels which is not good.
>>
>> This happens only with direct host1x client vi/csi driver unbind.
>>
>> Need to find better place to free host1x client driver data structure=20
>> to allow direct client driver unbind->bind.
>>