From: Hans Verkuil <hverkuil-qWit8jRvyhVmR6Xm/wNWPw@public.gmane.org> To: Sowjanya Komatineni <skomatineni-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>, thierry.reding-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org, jonathanh-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org, frankc-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org, helen.koike-ZGY8ohtN/8qB+jHODAdFcQ@public.gmane.org, sboyd-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org Cc: linux-media-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-clk-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org Subject: Re: [RFC PATCH v3 4/6] media: tegra: Add Tegra210 Video input driver Date: Thu, 19 Mar 2020 15:29:52 +0100 [thread overview] Message-ID: <bc571308-93e5-e720-1cac-eb3effe1acdd@xs4all.nl> (raw) In-Reply-To: <a5377068-3c70-1af4-6398-630d205e794b-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org> On 3/18/20 6:17 PM, Sowjanya Komatineni wrote: > > 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) >>>>>>>>> +{ >>>>>>>>> + struct device_node *node = csi->dev->of_node; >>>>>>>>> + unsigned int port_num; >>>>>>>>> + int ret; >>>>>>>>> + struct tegra_csi_channel *item; >>>>>>>>> + unsigned int tpg_channels = csi->soc->csi_max_channels; >>>>>>>>> + >>>>>>>>> + /* allocate CSI channel for each CSI x2 ports */ >>>>>>>>> + for (port_num = 0; port_num < tpg_channels; port_num++) { >>>>>>>>> + item = devm_kzalloc(csi->dev, sizeof(*item), >>>>>>>>> GFP_KERNEL); >>>>>>>> Using devm_*alloc can be dangerous. If someone unbinds the >>>>>>>> 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 >>>>> "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 >>>> --stream-mmap. >>>> Is that known? >>>> >>>> It's not a big deal at this moment, just want to know if this will >>>> be looked >>>> at later. >>>> >>>> Regards, >>>> >>>> Hans >>> >>> Weird, I tested streaming after unbind and bind as well and don't see >>> crash. Did below steps and tried several times unbind/bind as well. >>> >>> ./v4l2-ctl --stream-mmap --stream-count=1 -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=1 -d /dev/video3 >>> >>> Can you post call trace when you saw crash? >> >> Tried unbind when node is open with v4l2-ctl --sleep 10 as well and >> 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. That's indeed what I did. I don't want to try it again since I'm working from home and the Jetson is in the office. And once it crashes I need someone in the office to press the reset button. I hope I can pick it up next week to keep it at home as that will make testing a lot easier. > > Will look and have fix in v5. Nice! Thank you, Hans > > 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 >>>>>>> kernel >>>>>>> log. I didn't pursue this, and perhaps I did something wrong, but >>>>>>> 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 >>>>>>> media_device_unregister() >>>>>>> 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 >>>>>>> fixing it >>>>>>> in the future. >>>>>>> >>>>>>> Regards, >>>>>>> >>>>>>> Hans
WARNING: multiple messages have this Message-ID (diff)
From: Hans Verkuil <hverkuil@xs4all.nl> To: Sowjanya Komatineni <skomatineni@nvidia.com>, thierry.reding@gmail.com, jonathanh@nvidia.com, frankc@nvidia.com, helen.koike@collabora.com, sboyd@kernel.org Cc: linux-media@vger.kernel.org, devicetree@vger.kernel.org, linux-clk@vger.kernel.org, linux-tegra@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [RFC PATCH v3 4/6] media: tegra: Add Tegra210 Video input driver Date: Thu, 19 Mar 2020 15:29:52 +0100 [thread overview] Message-ID: <bc571308-93e5-e720-1cac-eb3effe1acdd@xs4all.nl> (raw) In-Reply-To: <a5377068-3c70-1af4-6398-630d205e794b@nvidia.com> On 3/18/20 6:17 PM, Sowjanya Komatineni wrote: > > 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) >>>>>>>>> +{ >>>>>>>>> + struct device_node *node = csi->dev->of_node; >>>>>>>>> + unsigned int port_num; >>>>>>>>> + int ret; >>>>>>>>> + struct tegra_csi_channel *item; >>>>>>>>> + unsigned int tpg_channels = csi->soc->csi_max_channels; >>>>>>>>> + >>>>>>>>> + /* allocate CSI channel for each CSI x2 ports */ >>>>>>>>> + for (port_num = 0; port_num < tpg_channels; port_num++) { >>>>>>>>> + item = devm_kzalloc(csi->dev, sizeof(*item), >>>>>>>>> GFP_KERNEL); >>>>>>>> Using devm_*alloc can be dangerous. If someone unbinds the >>>>>>>> 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 >>>>> "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 >>>> --stream-mmap. >>>> Is that known? >>>> >>>> It's not a big deal at this moment, just want to know if this will >>>> be looked >>>> at later. >>>> >>>> Regards, >>>> >>>> Hans >>> >>> Weird, I tested streaming after unbind and bind as well and don't see >>> crash. Did below steps and tried several times unbind/bind as well. >>> >>> ./v4l2-ctl --stream-mmap --stream-count=1 -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=1 -d /dev/video3 >>> >>> Can you post call trace when you saw crash? >> >> Tried unbind when node is open with v4l2-ctl --sleep 10 as well and >> 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. That's indeed what I did. I don't want to try it again since I'm working from home and the Jetson is in the office. And once it crashes I need someone in the office to press the reset button. I hope I can pick it up next week to keep it at home as that will make testing a lot easier. > > Will look and have fix in v5. Nice! Thank you, Hans > > 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 >>>>>>> kernel >>>>>>> log. I didn't pursue this, and perhaps I did something wrong, but >>>>>>> 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 >>>>>>> media_device_unregister() >>>>>>> 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 >>>>>>> fixing it >>>>>>> in the future. >>>>>>> >>>>>>> Regards, >>>>>>> >>>>>>> Hans
next prev parent reply other threads:[~2020-03-19 14:29 UTC|newest] Thread overview: 73+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-02-14 18:23 [RFC PATCH v3 0/6] Add Tegra driver for video capture Sowjanya Komatineni 2020-02-14 18:23 ` Sowjanya Komatineni 2020-02-14 18:23 ` [RFC PATCH v3 2/6] clk: tegra: Add Tegra210 CSI TPG clock gate Sowjanya Komatineni 2020-02-14 18:23 ` Sowjanya Komatineni 2020-02-14 18:23 ` [RFC PATCH v3 3/6] dt-binding: tegra: Add VI and CSI bindings Sowjanya Komatineni 2020-02-14 18:23 ` Sowjanya Komatineni [not found] ` <1581704608-31219-4-git-send-email-skomatineni-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org> 2020-02-18 23:15 ` Rob Herring 2020-02-18 23:15 ` Rob Herring 2020-02-19 3:28 ` Sowjanya Komatineni 2020-02-19 3:28 ` Sowjanya Komatineni 2020-02-20 19:45 ` Rob Herring [not found] ` <CAL_JsqKAVBS-KvP60Bv2JBQjUzTUgicx33nShn4enFpvysS9YA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org> 2020-02-20 20:39 ` Sowjanya Komatineni 2020-02-20 20:39 ` Sowjanya Komatineni [not found] ` <1581704608-31219-1-git-send-email-skomatineni-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org> 2020-02-14 18:23 ` [RFC PATCH v3 1/6] dt-bindings: clock: tegra: Add clk id for CSI TPG clock Sowjanya Komatineni 2020-02-14 18:23 ` Sowjanya Komatineni 2020-02-14 18:23 ` [RFC PATCH v3 4/6] media: tegra: Add Tegra210 Video input driver Sowjanya Komatineni 2020-02-14 18:23 ` Sowjanya Komatineni 2020-02-16 11:03 ` Hans Verkuil [not found] ` <30e417ba-84e1-63d2-de74-22cfe859bddb-qWit8jRvyhVmR6Xm/wNWPw@public.gmane.org> 2020-02-16 19:54 ` Sowjanya Komatineni 2020-02-16 19:54 ` Sowjanya Komatineni [not found] ` <920b4276-b2ca-646c-a21b-ca0b9bacf471-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org> 2020-02-16 20:11 ` Sowjanya Komatineni 2020-02-16 20:11 ` Sowjanya Komatineni 2020-02-16 20:22 ` Sowjanya Komatineni 2020-02-16 20:22 ` Sowjanya Komatineni [not found] ` <0f84d37c-105f-8de6-c922-186d2f9ea156-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org> 2020-02-17 8:04 ` Hans Verkuil 2020-02-17 8:04 ` Hans Verkuil [not found] ` <44fc39f4-8e9f-bcab-8642-fe1cb332016a-qWit8jRvyhVmR6Xm/wNWPw@public.gmane.org> 2020-02-18 0:59 ` Sowjanya Komatineni 2020-02-18 0:59 ` Sowjanya Komatineni 2020-02-18 1:04 ` Sowjanya Komatineni 2020-02-18 1:04 ` Sowjanya Komatineni 2020-02-18 3:19 ` Sowjanya Komatineni 2020-02-18 3:19 ` Sowjanya Komatineni [not found] ` <32ebc124-cb2d-f545-a5a0-d71192af8219-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org> 2020-02-19 15:08 ` Hans Verkuil 2020-02-19 15:08 ` Hans Verkuil 2020-02-19 16:22 ` Sowjanya Komatineni 2020-02-19 16:22 ` Sowjanya Komatineni [not found] ` <fc7b975a-dffa-4826-7ae5-40abb1f16b3d-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org> 2020-02-20 0:09 ` Sowjanya Komatineni 2020-02-20 0:09 ` Sowjanya Komatineni [not found] ` <3adacc07-7e3a-2d06-8d18-003b004ede17-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org> 2020-02-20 9:29 ` Hans Verkuil 2020-02-20 9:29 ` Hans Verkuil [not found] ` <dae3a6dd-f7ab-5e0f-08a9-2b0be4c68fe1-qWit8jRvyhVmR6Xm/wNWPw@public.gmane.org> 2020-02-20 16:21 ` Sowjanya Komatineni 2020-02-20 16:21 ` Sowjanya Komatineni 2020-02-20 12:44 ` Hans Verkuil [not found] ` <b301c247-537d-d78e-b057-a3225b10de7e-qWit8jRvyhVmR6Xm/wNWPw@public.gmane.org> 2020-02-20 13:33 ` Hans Verkuil 2020-02-20 13:33 ` Hans Verkuil 2020-02-20 17:29 ` Sowjanya Komatineni 2020-02-20 17:29 ` Sowjanya Komatineni 2020-02-20 19:11 ` Sowjanya Komatineni 2020-02-20 19:11 ` Sowjanya Komatineni [not found] ` <b3933aa1-0717-183d-f00c-2d5fd6836a18-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org> 2020-02-24 4:45 ` Sowjanya Komatineni 2020-02-24 4:45 ` Sowjanya Komatineni [not found] ` <12a36c2a-593c-e555-d44e-e2e6c4c1a562-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org> 2020-03-18 11:48 ` Hans Verkuil 2020-03-18 11:48 ` Hans Verkuil 2020-03-18 16:14 ` Sowjanya Komatineni 2020-03-18 16:14 ` Sowjanya Komatineni [not found] ` <19081d90-62cc-e6eb-0337-f108fb6ca9bc-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org> 2020-03-18 16:25 ` Sowjanya Komatineni 2020-03-18 16:25 ` Sowjanya Komatineni [not found] ` <061eabf1-4b6f-83c0-6851-df8a193a84e8-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org> 2020-03-18 17:17 ` Sowjanya Komatineni 2020-03-18 17:17 ` Sowjanya Komatineni [not found] ` <a5377068-3c70-1af4-6398-630d205e794b-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org> 2020-03-19 14:29 ` Hans Verkuil [this message] 2020-03-19 14:29 ` Hans Verkuil [not found] ` <bc571308-93e5-e720-1cac-eb3effe1acdd-qWit8jRvyhVmR6Xm/wNWPw@public.gmane.org> 2020-03-19 18:49 ` Sowjanya Komatineni 2020-03-19 18:49 ` Sowjanya Komatineni 2020-02-26 4:49 ` Sowjanya Komatineni 2020-02-26 4:49 ` Sowjanya Komatineni [not found] ` <821f0878-56da-9b51-425a-9d6fb65d2e0c-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org> 2020-02-26 5:50 ` Sowjanya Komatineni 2020-02-26 5:50 ` Sowjanya Komatineni 2020-02-14 18:23 ` [RFC PATCH v3 5/6] MAINTAINERS: Add Tegra Video driver section Sowjanya Komatineni 2020-02-14 18:23 ` Sowjanya Komatineni 2020-02-14 18:23 ` [RFC PATCH v3 6/6] arm64: tegra: Add Tegra VI CSI support in device tree Sowjanya Komatineni 2020-02-14 18:23 ` Sowjanya Komatineni 2020-02-17 14:26 ` [RFC PATCH v3 0/6] Add Tegra driver for video capture Hans Verkuil 2020-02-17 14:26 ` Hans Verkuil
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