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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> Message-ID: <061eabf1-4b6f-83c0-6851-df8a193a84e8@nvidia.com> Date: Wed, 18 Mar 2020 09:25:12 -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: <19081d90-62cc-e6eb-0337-f108fb6ca9bc@nvidia.com> X-Originating-IP: [172.20.13.39] X-ClientProxiedBy: HQMAIL107.nvidia.com (172.20.187.13) 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=1584548597; bh=4AkSXVqHDrCp7I1KwaJ8XUtzUo2d9f+JxqC9kjrpnek=; 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=ox330UjFEh91bRxhmgIQsRxrtGNZ61NEwV6wSmfZk3KiOCM+oSZMDVdAnkmab/5kH jcP4ZP+T58yGHrw5nHzb3hsj8d2XTQ3CNJ08vtxdalAvlfuXqwxUXJuAwpqZEMNQxY b20NyBh3ceIY5Tb7EskrUHJUXQ6no8S4A9opXOTKKAySQSL4pBGk82Vylcam3ZWj82 IeCTa8pmJbwQJ3QcqRVK/shyGYXIpWyYaIq8GArYfl+wPP4Uf5+5/ByEfOXd/gfpZI Vkshrk9+67NTbuh1Tlw6q/12BOKt1cC+QUPqDcXuNBVPes1cMHDuw514HaskrZ7ILQ 6uOdqTh9pIH1g== Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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_max= _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; p= ort_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 sure >>> unbind/bind works properly. >>> >>> BTW, tegra vi and csi are registered as clients to host1x video 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 be=20 >> 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... > >>>>> 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 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