Hi Hans, On Mon, Oct 07, 2024 at 04:53:30PM +0200, Hans Verkuil wrote: > On 07/10/2024 16:44, Laurent Pinchart wrote: > > On Mon, Oct 07, 2024 at 09:46:47AM +0200, Hans Verkuil wrote: > >> Hi Laurent, > >> > >> Just a reminder: I have extensively reviewed this patch here: > >> > >> https://lore.kernel.org/linux-media/f4c49ccf-9dc9-475a-8fc9-4ef4c85a729a@xxxxxxxxx/ > >> > >> and here (specifically checking for mmap() races): > >> > >> https://lore.kernel.org/linux-media/1a10530f-b4bb-4244-84ff-1f2365ae9b23@xxxxxxxxx/ > >> > >> To the best of my ability I believe this patch is correct. > >> > >> Unless you have any additional concerns I plan to take this patch as a fix for > >> v6.12 on Monday next week. > > > > I thought we had an agreement that I could submit an alternative fix for > > v6.12. Can you therefore delay merging this patch until v6.12-rc6 ? > > Correct, if there is indeed something wrong with this patch and an alternative > fix is needed (or at least should be considered). > > But I see nothing wrong with this patch after careful analysis. If you disagree > with my analysis, and you think I missed a possible race condition, then that's > a reason to wait for a better fix. Otherwise there is no point in waiting any longer. I'm in Montréal this week for the GStreamer conference and XDC. I'll reply to your last e-mail early next week, let's make a decision then. Surely this can wait until -rc4 before being merged ? > >> Alternatively, you can make a PR for 6.12 with this patch that I can pull from. > >> > >> Regards, > >> > >> Hans > >> > >> On 26/09/2024 07:59, Ricardo Ribalda wrote: > >>> uvc_unregister_video() can be called asynchronously from > >>> uvc_disconnect(). If the device is still streaming when that happens, a > >>> plethora of race conditions can occur. > >>> > >>> Make sure that the device has stopped streaming before exiting this > >>> function. > >>> > >>> If the user still holds handles to the driver's file descriptors, any > >>> ioctl will return -ENODEV from the v4l2 core. > >>> > >>> This change makes uvc more consistent with the rest of the v4l2 drivers > >>> using the vb2_fop_* and vb2_ioctl_* helpers. > >>> > >>> Reviewed-by: Hans Verkuil <hverkuil-cisco@xxxxxxxxx> > >>> Suggested-by: Hans Verkuil <hverkuil-cisco@xxxxxxxxx> > >>> Signed-off-by: Ricardo Ribalda <ribalda@xxxxxxxxxxxx> > >>> --- > >>> This patch was part of the series: > >>> https://patchwork.linuxtv.org/project/linux-media/list/?series=13064 > >>> > >>> Moved out from it to ease the review. > >>> --- > >>> drivers/media/usb/uvc/uvc_driver.c | 32 +++++++++++++++++++++++++++++++- > >>> 1 file changed, 31 insertions(+), 1 deletion(-) > >>> > >>> diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c > >>> index f0febdc08c2d..bee150b852e4 100644 > >>> --- a/drivers/media/usb/uvc/uvc_driver.c > >>> +++ b/drivers/media/usb/uvc/uvc_driver.c > >>> @@ -1919,11 +1919,41 @@ static void uvc_unregister_video(struct uvc_device *dev) > >>> struct uvc_streaming *stream; > >>> > >>> list_for_each_entry(stream, &dev->streams, list) { > >>> + /* Nothing to do here, continue. */ > >>> if (!video_is_registered(&stream->vdev)) > >>> continue; > >>> > >>> + /* > >>> + * For stream->vdev we follow the same logic as: > >>> + * vb2_video_unregister_device(). > >>> + */ > >>> + > >>> + /* 1. Take a reference to vdev */ > >>> + get_device(&stream->vdev.dev); > >>> + > >>> + /* 2. Ensure that no new ioctls can be called. */ > >>> video_unregister_device(&stream->vdev); > >>> - video_unregister_device(&stream->meta.vdev); > >>> + > >>> + /* 3. Wait for old ioctls to finish. */ > >>> + mutex_lock(&stream->mutex); > >>> + > >>> + /* 4. Stop streaming. */ > >>> + uvc_queue_release(&stream->queue); > >>> + > >>> + mutex_unlock(&stream->mutex); > >>> + > >>> + put_device(&stream->vdev.dev); > >>> + > >>> + /* > >>> + * For stream->meta.vdev we can directly call: > >>> + * vb2_video_unregister_device(). > >>> + */ > >>> + vb2_video_unregister_device(&stream->meta.vdev); > >>> + > >>> + /* > >>> + * Now both vdevs are not streaming and all the ioctls will > >>> + * return -ENODEV. > >>> + */ > >>> > >>> uvc_debugfs_cleanup_stream(stream); > >>> } > >>> > >>> --- > >>> base-commit: 81ee62e8d09ee3c7107d11c8bbfd64073ab601ad > >>> change-id: 20240926-uvc_stop_streaming-6e9fd20e97bc -- Regards, Laurent Pinchart
