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@xxxxxxxxxxxx/ 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@xxxxxxxxxxxxxxx/ Which will make obsolete a lof (all?) of the video_is_registered() checks on Guenters 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! To: Mauro Carvalho Chehab <mchehab@xxxxxxxxxx> Cc: Guenter Roeck <linux@xxxxxxxxxxxx> Cc: Max Staudt <mstaudt@xxxxxxxxxxxx> Cc: Tomasz Figa <tfiga@xxxxxxxxxxxx> Cc: Sakari Ailus <sakari.ailus@xxxxxx> Cc: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx> Cc: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> Cc: Hans Verkuil <hverkuil-cisco@xxxxxxxxx> Cc: linux-media@xxxxxxxxxxxxxxx Cc: linux-kernel@xxxxxxxxxxxxxxx Cc: Sean Paul <seanpaul@xxxxxxxxxxxx> Signed-off-by: Ricardo Ribalda <ribalda@xxxxxxxxxxxx> --- 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@xxxxxxxxxxxx --- Guenter Roeck (3): media: uvcvideo: Cancel async worker earlier media: uvcvideo: Lock video streams and queues while unregistering media: uvcvideo: Release stream queue when unregistering video device drivers/media/usb/uvc/uvc_ctrl.c | 11 +++++++---- drivers/media/usb/uvc/uvc_driver.c | 12 ++++++++++++ drivers/media/usb/uvc/uvcvideo.h | 1 + 3 files changed, 20 insertions(+), 4 deletions(-) --- base-commit: 63355b9884b3d1677de6bd1517cd2b8a9bf53978 change-id: 20230309-guenter-mini-89861b084ef1 Best regards, -- Ricardo Ribalda <ribalda@xxxxxxxxxxxx>
