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Subject[PATCH v3 0/3] uvcvideo: Attempt N to land UVC race conditions fixes
Date
Back in 2020 Guenter published a set of patches to fix some race
conditions on UVC.
https://lore.kernel.org/all/20200917022547.198090-5-linux@roeck-us.net/

That kind of race conditions are not only seen on UVC, but are a common
sin on almost all the kernel, so this is what it was decided back then
that we should try to fix them at higher levels.

After that. A lot of video_is_registered() were added to the core:

```
ribalda@alco:~/work/linux$ git grep is_registered drivers/media/v4l2-core/
drivers/media/v4l2-core/v4l2-compat-ioctl32.c: if (!video_is_registered(vdev))
drivers/media/v4l2-core/v4l2-dev.c: if (video_is_registered(vdev))
drivers/media/v4l2-core/v4l2-dev.c: if (video_is_registered(vdev))
drivers/media/v4l2-core/v4l2-dev.c: if (video_is_registered(vdev)) {
drivers/media/v4l2-core/v4l2-dev.c: if (video_is_registered(vdev))
drivers/media/v4l2-core/v4l2-dev.c: if (!video_is_registered(vdev))
drivers/media/v4l2-core/v4l2-dev.c: if (video_is_registered(vdev))
drivers/media/v4l2-core/v4l2-dev.c: if (vdev == NULL || !video_is_registered(vdev)) {
drivers/media/v4l2-core/v4l2-dev.c: if (video_is_registered(vdev))
drivers/media/v4l2-core/v4l2-dev.c: if (!vdev || !video_is_registered(vdev))
drivers/media/v4l2-core/v4l2-ioctl.c: if (!video_is_registered(vfd)) {
drivers/media/v4l2-core/v4l2-subdev.c: if (video_is_registered(vdev)) {
```

And recently Sakari is trying to land:
https://lore.kernel.org/linux-media/20230201214535.347075-1-sakari.ailus@linux.intel.com/

Which will make obsolete a lot of (all?) of the video_is_registered() checks on
Guenter's patches.

Besides those checks, there were some other valid races fixed on his
patches.

This series is just a rebase of what I think is missing on UVC even
if we fixed v4l2/core with all the video_is_register() checks removed.

Thanks!

Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
---
Changes in v3:
- Introduce media: uvcvideo: Do not halt the device after disconnect
- Introduce media: uvcvideo: Always use uvc_status_stop()
- Link to v2: https://lore.kernel.org/r/20230309-guenter-mini-v2-0-e6410d590d43@chromium.org

Changes in v2:
- Actually send the series to the ML an not only to individuals.
- Link to v1: https://lore.kernel.org/r/20230309-guenter-mini-v1-0-627d10cf6e96@chromium.org

---
Guenter Roeck (1):
media: uvcvideo: Lock video streams and queues while unregistering

Ricardo Ribalda (2):
media: uvcvideo: Always use uvc_status_stop()
media: uvcvideo: Do not halt the device after disconnect

drivers/media/usb/uvc/uvc_ctrl.c | 4 ----
drivers/media/usb/uvc/uvc_driver.c | 11 ++++++++++
drivers/media/usb/uvc/uvc_status.c | 2 +-
drivers/media/usb/uvc/uvc_video.c | 45 ++++++++++++++++++++++++--------------
drivers/media/usb/uvc/uvcvideo.h | 2 ++
5 files changed, 42 insertions(+), 22 deletions(-)
---
base-commit: 98b1cc82c4affc16f5598d4fa14b1858671b2263
change-id: 20230309-guenter-mini-89861b084ef1

Best regards,
--
Ricardo Ribalda <ribalda@chromium.org>

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