From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sowjanya Komatineni Subject: Re: [RFC PATCH v7 6/9] media: tegra: Add Tegra210 Video input driver Date: Wed, 15 Apr 2020 10:21:15 -0700 Message-ID: <6afa951e-d904-f3c0-053f-82a02fb18979@nvidia.com> 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> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: quoted-printable Return-path: In-Reply-To: Content-Language: en-US Sender: linux-clk-owner@vger.kernel.org To: Dmitry Osipenko , thierry.reding@gmail.com, jonathanh@nvidia.com, frankc@nvidia.com, hverkuil@xs4all.nl, sakari.ailus@iki.fi, helen.koike@collabora.com Cc: 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 List-Id: linux-tegra@vger.kernel.org On 4/15/20 9:54 AM, Sowjanya Komatineni wrote: > > On 4/15/20 7:22 AM, Dmitry Osipenko wrote: >> External email: Use caution opening links or attachments >> >> >> 15.04.2020 05:57, Sowjanya Komatineni =D0=BF=D0=B8=D1=88=D0=B5=D1=82: >>> +static int tegra_csi_remove(struct platform_device *pdev) >>> +{ >>> +=C2=A0=C2=A0=C2=A0=C2=A0 struct tegra_csi *csi =3D platform_get_drvdat= a(pdev); >>> +=C2=A0=C2=A0=C2=A0=C2=A0 int err; >>> + >>> +=C2=A0=C2=A0=C2=A0=C2=A0 err =3D host1x_client_unregister(&csi->client= ); >>> +=C2=A0=C2=A0=C2=A0=C2=A0 if (err < 0) { >>> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2= =A0 dev_err(csi->dev, >>> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2= =A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 "failed to unregister h= ost1x client: %d\n", err); >>> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2= =A0 return err; >>> +=C2=A0=C2=A0=C2=A0=C2=A0 } >>> + >>> +=C2=A0=C2=A0=C2=A0=C2=A0 pm_runtime_disable(csi->dev); >>> +=C2=A0=C2=A0=C2=A0=C2=A0 kfree(csi); >> IIRC, the driver removal is invoked on the unbinding. Hence, I'm not >> sure how moving away from the resource-managed API helps here. Could you >> please explain in a more details? >> >> Have you tried to test this driver under KASAN? I suspect that you just >> masked the problem, instead of fixing it. > Using devm_kzalloc for vi/csi structures based on prior feedback=20 > request to switch to use kzalloc all over this driver. > > Hi Hans, > > video devices lifetime is till video device nodes are released. So,=20 > v4l2 device release callback does the release of tegra channel=20 > allocation which hold video device. > > Below are the 3 possible cases of unbind/unload, > > 1. during tegra-video module unload, if v4l2 device refcnt is not 0=20 > which is the case when any of video device node handle is kept opened=20 > then unloading module will not happen and module refcnt is also=20 > non-zero and unloading tegra-video module reports module in use. > > 2. during tegra-video driver unbind, tegra-video driver removal will=20 > do vi/csi clients exit ops which unregisters video device allocated=20 > memory during release callback of v4l2 device. vi/csi structure=20 > allocation remains same as vi/csi driver removal will not happen in=20 > this case. > > > 3. during direct host1x client drivers vi/csi unbind, both=20 > host1x_clients vi/csi gets unregistered, deletes host1x logical device=20 > which executes tegra-video driver removal() -> vi/csi exit() before=20 > vi/csi memory gets freed in vi/csi driver remove(). > > So, any active streaming will stop and video devices are unregistered=20 > during direct client driver unbind prior to freeing vi/csi memory. > > Also vi/csi driver remove does explicit free vi/csi as its allocated=20 > with kzalloc. So not sure how using kzalloc is different to=20 > devm_kzalloc for vi/csi structure in terms of when vi/csi memory gets=20 > freed? > > Except for channel allocation which holds video device and as video=20 > device life time is beyond tegra-video module unbind->vi exit(), looks=20 > like we can use devm_kzalloc for vi/csi. > > > Can you please comment if you still think we need to use kzalloc=20 > rather than devm_kzalloc for vi/csi structure allocation? > > Thanks > > Sowjanya > One more case is when video device node is kept opened with v4l2-ctl=20 sleep (rather than streaming), where it will keep device node open for=20 specified time and if direct vi client driver unbind happens then vi=20 driver remove() will free vi memory before v4l2 device release happens. But I don't see any crash or errors with this case. Also if we allow direct client driver unbind, then vi structure memory=20 lifetime should also be till v4l2 device release happens. But we can free vi in v4l2 device release callback as in case when=20 device node is not kept opened, video device release happens immediate=20 and we cant free vi that early. Hans/Thierry, Can you please comment on this case? Thanks Sowjanya 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=-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 11D8FC3815B for ; Wed, 15 Apr 2020 17:21:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E3D472084D for ; Wed, 15 Apr 2020 17:21:31 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=nvidia.com header.i=@nvidia.com header.b="Zu8LthJ3" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2410853AbgDORVa (ORCPT ); Wed, 15 Apr 2020 13:21:30 -0400 Received: from hqnvemgate26.nvidia.com ([216.228.121.65]:9097 "EHLO hqnvemgate26.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2405973AbgDORVU (ORCPT ); Wed, 15 Apr 2020 13:21:20 -0400 Received: from hqpgpgate101.nvidia.com (Not Verified[216.228.121.13]) by hqnvemgate26.nvidia.com (using TLS: TLSv1.2, DES-CBC3-SHA) id ; Wed, 15 Apr 2020 10:21:05 -0700 Received: from hqmail.nvidia.com ([172.20.161.6]) by hqpgpgate101.nvidia.com (PGP Universal service); Wed, 15 Apr 2020 10:21:18 -0700 X-PGP-Universal: processed; by hqpgpgate101.nvidia.com on Wed, 15 Apr 2020 10:21:18 -0700 Received: from DRHQMAIL107.nvidia.com (10.27.9.16) by HQMAIL109.nvidia.com (172.20.187.15) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Wed, 15 Apr 2020 17:21:17 +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 17:21:16 +0000 Subject: Re: [RFC PATCH v7 6/9] media: tegra: Add Tegra210 Video input driver From: Sowjanya Komatineni To: Dmitry Osipenko , , , , , , CC: , , , , , 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> Message-ID: <6afa951e-d904-f3c0-053f-82a02fb18979@nvidia.com> Date: Wed, 15 Apr 2020 10:21:15 -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: X-Originating-IP: [10.124.1.5] X-ClientProxiedBy: HQMAIL111.nvidia.com (172.20.187.18) 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=1586971265; bh=aYOmnHhbLsi1mW5Ldu2gZgxLMlRJkwu6eXD1fASdZvQ=; 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=Zu8LthJ3WtnIlnbQjYiwgebX9Bktgs+JZRBi+0urq/Tb5OyckSMwua7n6ooUd90MJ Lw00ZBScvnj74pZKmVXwPs8nd1HB07AXJbc/fm3eFreYpTvmeSQVA39A5W+DdfVNu9 MeNQglGl/Ki6Pp4tu9MsZxZyFdGb17r/H047XDMeWgA0Ev7ltqY265lNQCa1pGKDZY Hgu5GeKVN+3HTXoQ3ipmbEJ1bHiKAUmcduGJ0rPixcaZmsWJ9z4IPPgcVKldIW7zY3 WleQtkdZeYP3dVcZ/jHZxVB6tb3joDqVk/UPfb79RVedx/ZcgsqROdGj+uy6M6eEXH TA9iCaW8bvWHQ== Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 4/15/20 9:54 AM, Sowjanya Komatineni wrote: > > On 4/15/20 7:22 AM, Dmitry Osipenko wrote: >> External email: Use caution opening links or attachments >> >> >> 15.04.2020 05:57, Sowjanya Komatineni =D0=BF=D0=B8=D1=88=D0=B5=D1=82: >>> +static int tegra_csi_remove(struct platform_device *pdev) >>> +{ >>> +=C2=A0=C2=A0=C2=A0=C2=A0 struct tegra_csi *csi =3D platform_get_drvdat= a(pdev); >>> +=C2=A0=C2=A0=C2=A0=C2=A0 int err; >>> + >>> +=C2=A0=C2=A0=C2=A0=C2=A0 err =3D host1x_client_unregister(&csi->client= ); >>> +=C2=A0=C2=A0=C2=A0=C2=A0 if (err < 0) { >>> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2= =A0 dev_err(csi->dev, >>> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2= =A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 "failed to unregister h= ost1x client: %d\n", err); >>> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2= =A0 return err; >>> +=C2=A0=C2=A0=C2=A0=C2=A0 } >>> + >>> +=C2=A0=C2=A0=C2=A0=C2=A0 pm_runtime_disable(csi->dev); >>> +=C2=A0=C2=A0=C2=A0=C2=A0 kfree(csi); >> IIRC, the driver removal is invoked on the unbinding. Hence, I'm not >> sure how moving away from the resource-managed API helps here. Could you >> please explain in a more details? >> >> Have you tried to test this driver under KASAN? I suspect that you just >> masked the problem, instead of fixing it. > Using devm_kzalloc for vi/csi structures based on prior feedback=20 > request to switch to use kzalloc all over this driver. > > Hi Hans, > > video devices lifetime is till video device nodes are released. So,=20 > v4l2 device release callback does the release of tegra channel=20 > allocation which hold video device. > > Below are the 3 possible cases of unbind/unload, > > 1. during tegra-video module unload, if v4l2 device refcnt is not 0=20 > which is the case when any of video device node handle is kept opened=20 > then unloading module will not happen and module refcnt is also=20 > non-zero and unloading tegra-video module reports module in use. > > 2. during tegra-video driver unbind, tegra-video driver removal will=20 > do vi/csi clients exit ops which unregisters video device allocated=20 > memory during release callback of v4l2 device. vi/csi structure=20 > allocation remains same as vi/csi driver removal will not happen in=20 > this case. > > > 3. during direct host1x client drivers vi/csi unbind, both=20 > host1x_clients vi/csi gets unregistered, deletes host1x logical device=20 > which executes tegra-video driver removal() -> vi/csi exit() before=20 > vi/csi memory gets freed in vi/csi driver remove(). > > So, any active streaming will stop and video devices are unregistered=20 > during direct client driver unbind prior to freeing vi/csi memory. > > Also vi/csi driver remove does explicit free vi/csi as its allocated=20 > with kzalloc. So not sure how using kzalloc is different to=20 > devm_kzalloc for vi/csi structure in terms of when vi/csi memory gets=20 > freed? > > Except for channel allocation which holds video device and as video=20 > device life time is beyond tegra-video module unbind->vi exit(), looks=20 > like we can use devm_kzalloc for vi/csi. > > > Can you please comment if you still think we need to use kzalloc=20 > rather than devm_kzalloc for vi/csi structure allocation? > > Thanks > > Sowjanya > One more case is when video device node is kept opened with v4l2-ctl=20 sleep (rather than streaming), where it will keep device node open for=20 specified time and if direct vi client driver unbind happens then vi=20 driver remove() will free vi memory before v4l2 device release happens. But I don't see any crash or errors with this case. Also if we allow direct client driver unbind, then vi structure memory=20 lifetime should also be till v4l2 device release happens. But we can free vi in v4l2 device release callback as in case when=20 device node is not kept opened, video device release happens immediate=20 and we cant free vi that early. Hans/Thierry, Can you please comment on this case? Thanks Sowjanya