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<12a36c2a-593c-e555-d44e-e2e6c4c1a562@nvidia.com> <5f54c018-5670-8193-7c68-969f9bde92f6@xs4all.nl> <19081d90-62cc-e6eb-0337-f108fb6ca9bc@nvidia.com> <061eabf1-4b6f-83c0-6851-df8a193a84e8@nvidia.com> Message-ID: Date: Wed, 18 Mar 2020 10:17:12 -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: <061eabf1-4b6f-83c0-6851-df8a193a84e8@nvidia.com> X-Originating-IP: [10.124.1.5] X-ClientProxiedBy: HQMAIL101.nvidia.com (172.20.187.10) To HQMAIL107.nvidia.com (172.20.187.13) 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=1584551752; bh=oBKNPTi9GLdtryL/j8HF1CfdlMDUDx2LP07rQWMZdTU=; 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=XU11EO/Fztnr3hGAYUHf3fIwU8CfkRR4/nx842XtN96L9Mhi1h+aWyNLvtQCdYkro 18M4Pb1niPTJifZ8vx0a1xDqE8jgIfYWRdyopv0/QqVsZ+1MJkb/UosfaVYN0Np3Q7 o9JSwPvj7qzGVang7q2bgTQLlSZhtkWDFpSwsPublH5QrFAb9rUWk2JNm3DqAo/zuR +uugeK+19xm8ckxWwB0tSAvj2+lkDl4v2lqV3mZnIyc6laiIEt5DA6/sHl/krvG+p0 YOBRO0sC17o6Td8hVI//ptF8gilEfovPNpLAzHZJSirKQMqvZedZoP1El/DsJSRv/s nMZY7U/HZvt1g== Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 3/18/20 9:25 AM, Sowjanya Komatineni wrote: > > On 3/18/20 9:14 AM, Sowjanya Komatineni wrote: >> >> On 3/18/20 4:48 AM, Hans Verkuil wrote: >>> External email: Use caution opening links or attachments >>> >>> >>> On 2/24/20 5:45 AM, Sowjanya Komatineni wrote: >>>> On 2/20/20 11:11 AM, Sowjanya Komatineni wrote: >>>>> On 2/20/20 5:33 AM, Hans Verkuil wrote: >>>>>> External email: Use caution opening links or attachments >>>>>> >>>>>> >>>>>> (Replying to myself so I can explain this a bit more) >>>>>> >>>>>> On 2/20/20 1:44 PM, Hans Verkuil wrote: >>>>>>>> + >>>>>>>> +static int tegra_csi_tpg_channels_alloc(struct tegra_csi *csi) >>>>>>>> +{ >>>>>>>> +=C2=A0=C2=A0=C2=A0 struct device_node *node =3D csi->dev->of_node= ; >>>>>>>> +=C2=A0=C2=A0=C2=A0 unsigned int port_num; >>>>>>>> +=C2=A0=C2=A0=C2=A0 int ret; >>>>>>>> +=C2=A0=C2=A0=C2=A0 struct tegra_csi_channel *item; >>>>>>>> +=C2=A0=C2=A0=C2=A0 unsigned int tpg_channels =3D csi->soc->csi_ma= x_channels; >>>>>>>> + >>>>>>>> +=C2=A0=C2=A0=C2=A0 /* allocate CSI channel for each CSI x2 ports = */ >>>>>>>> +=C2=A0=C2=A0=C2=A0 for (port_num =3D 0; port_num < tpg_channels; = port_num++) { >>>>>>>> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2= =A0 item =3D devm_kzalloc(csi->dev, sizeof(*item),=20 >>>>>>>> GFP_KERNEL); >>>>>>> Using devm_*alloc can be dangerous. If someone unbinds the=20 >>>>>>> driver, then >>>>>>> all memory allocated with devm_ is immediately freed. But if an >>>>>>> application >>>>>>> still has a filehandle open, then when it closes it it might still >>>>>>> reference >>>>>>> this already-freed memory. >>>>>>> >>>>>>> I recommend that you avoid using devm_*alloc for media drivers. >>>>>> A good test is to unbind & bind the driver: >>>>>> >>>>>> cd /sys/devices/platform/50000000.host1x/54080000.vi/driver >>>>>> echo -n 54080000.vi >unbind >>>>>> echo -n 54080000.vi >bind >>>>>> >>>>>> First just do this without the driver being used. That already >>>>>> gives me 'list_del corruption' kernel messages (list debugging >>>>>> is turned on in my kernel). >>>> Will fix in v4 to use kzalloc and also proper release v4l2 to make=20 >>>> sure >>>> unbind/bind works properly. >>>> >>>> BTW, tegra vi and csi are registered as clients to host1x video=20 >>>> driver. >>>> >>>> So, unbind and bind should be done with host1x video driver=20 >>>> "tegra-video" >>>> >>>> cd /sys/devices/platform/50000000.host1x/tegra-video/driver >>>> echo -n tegra-video > unbind >>>> echo -n tegra-video > bind >>> This still crashes with v4, at least if I am streaming with v4l2-ctl=20 >>> --stream-mmap. >>> Is that known? >>> >>> It's not a big deal at this moment, just want to know if this will=20 >>> be looked >>> at later. >>> >>> Regards, >>> >>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 Hans >> >> Weird, I tested streaming after unbind and bind as well and don't see=20 >> crash. Did below steps and tried several times unbind/bind as well. >> >> ./v4l2-ctl --stream-mmap --stream-count=3D1 -d /dev/video3 >> cd /sys/devices/platform/50000000.host1x/tegra-video/driver >> echo -n tegra-video > unbind >> sleep 1 >> echo -n tegra-video > bind >> cd /home/ubuntu >> ./v4l2-ctl --stream-mmap --stream-count=3D1 -d /dev/video3 >> >> Can you post call trace when you saw crash? > > Tried unbind when=C2=A0 node is open with v4l2-ctl --sleep 10 as well and= =20 > bind back. > > I don't see crash. Will confirm on doing unbind/bind with stream-mmap... > Able to repro when unbind/bind happens while stream-mmap. Will look and have fix in v5. Thanks Hans. >> >>>>>> Note that this first test is basically identical to a rmmod/modprobe >>>>>> of the driver. But when I compiled the driver as a module it didn't >>>>>> create any video device nodes! Nor did I see any errors in the=20 >>>>>> kernel >>>>>> log. I didn't pursue this, and perhaps I did something wrong, but=20 >>>>>> it's >>>>>> worth taking a look at. >>>>>> >>>>>> The next step would be to have a video node open with: >>>>>> >>>>>> v4l2-ctl --sleep 10 >>>>>> >>>>>> then while it is sleeping unbind the driver and see what happens >>>>>> when v4l2-ctl exits. >>>>>> >>>>>> Worst case is when you are streaming: >>>>>> >>>>>> v4l2-ctl --stream-mmap >>>>>> >>>>>> and then unbind. >>>>>> >>>>>> In general, the best way to get this to work correctly is: >>>>>> >>>>>> 1) don't use devm_*alloc >>>>>> 2) set the release callback of struct v4l2_device and do all freeing >>>>>> there. >>>>>> 3) in the platform remove() callback you call=20 >>>>>> media_device_unregister() >>>>>> =C2=A0=C2=A0=C2=A0=C2=A0 and video_unregister_device(). >>>>> Reg 3, in current patch, media_device_unregister is called in >>>>> host1x_video_remove >>>>> video_unregister_device happens during host1x_video_remove -> >>>>> host1x_device_exit -> tegra_vi_exit -> tegra_vi_channels_cleanup >>>>> >>>>>> It's worth getting this right in this early stage, rather than=20 >>>>>> fixing it >>>>>> in the future. >>>>>> >>>>>> Regards, >>>>>> >>>>>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 Hans