| Message ID | 20241203-uvc-fix-async-v6-0-26c867231118@chromium.org |
|---|---|
| Headers | show |
| Series | media: uvcvideo: Two +1 fixes for async controls | expand |
On Tue, 3 Dec 2024 at 22:20, Ricardo Ribalda <ribalda@chromium.org> wrote: > > When an async control is written, we copy a pointer to the file handle > that started the operation. That pointer will be used when the device is > done. Which could be anytime in the future. > > If the user closes that file descriptor, its structure will be freed, > and there will be one dangling pointer per pending async control, that > the driver will try to use. > > Clean all the dangling pointers during release(). > > To avoid adding a performance penalty in the most common case (no async > operation), a counter has been introduced with some logic to make sure > that it is properly handled. > > Cc: stable@vger.kernel.org > Fixes: e5225c820c05 ("media: uvcvideo: Send a control event when a Control Change interrupt arrives") > Reviewed-by: Hans de Goede <hdegoede@redhat.com> > Signed-off-by: Ricardo Ribalda <ribalda@chromium.org> > --- > drivers/media/usb/uvc/uvc_ctrl.c | 58 ++++++++++++++++++++++++++++++++++++++-- > drivers/media/usb/uvc/uvc_v4l2.c | 2 ++ > drivers/media/usb/uvc/uvcvideo.h | 9 ++++++- > 3 files changed, 66 insertions(+), 3 deletions(-) > > diff --git a/drivers/media/usb/uvc/uvc_ctrl.c b/drivers/media/usb/uvc/uvc_ctrl.c > index 42b0a0cdc51c..def502195528 100644 > --- a/drivers/media/usb/uvc/uvc_ctrl.c > +++ b/drivers/media/usb/uvc/uvc_ctrl.c > @@ -1579,6 +1579,40 @@ static void uvc_ctrl_send_slave_event(struct uvc_video_chain *chain, > uvc_ctrl_send_event(chain, handle, ctrl, mapping, val, changes); > } > > +static void uvc_ctrl_set_handle(struct uvc_fh *handle, struct uvc_control *ctrl, > + struct uvc_fh *new_handle) > +{ > + lockdep_assert_held(&handle->chain->ctrl_mutex); > + > + if (new_handle) { > + if (ctrl->handle) > + dev_warn_ratelimited(&handle->stream->dev->udev->dev, > + "UVC non compliance: Setting an async control with a pending operation."); > + > + if (new_handle == ctrl->handle) > + return; > + > + if (ctrl->handle) { > + WARN_ON(!ctrl->handle->pending_async_ctrls); > + if (ctrl->handle->pending_async_ctrls) > + ctrl->handle->pending_async_ctrls--; > + } > + > + ctrl->handle = new_handle; > + handle->pending_async_ctrls++; > + return; > + } > + > + /* Cannot clear the handle for a control not owned by us.*/ > + if (WARN_ON(ctrl->handle != handle)) > + return; > + > + ctrl->handle = NULL; > + if (WARN_ON(!handle->pending_async_ctrls)) > + return; > + handle->pending_async_ctrls--; > +} Laurent, If I have to redo the patch... would you be open to have two functions: uvc_ctrl_set_handle(struct uvc_fh *handle, struct uvc_control *ctrl) uvc_ctrl_clear_handle(struct uvc_fh *handle, struct uvc_control *ctrl) instead of this one? It might be me, but it looks uglier than before. If you like this code just disregard this message. Regards! > + > void uvc_ctrl_status_event(struct uvc_video_chain *chain, > struct uvc_control *ctrl, const u8 *data) > { > @@ -1589,7 +1623,8 @@ void uvc_ctrl_status_event(struct uvc_video_chain *chain, > mutex_lock(&chain->ctrl_mutex); > > handle = ctrl->handle; > - ctrl->handle = NULL; > + if (handle) > + uvc_ctrl_set_handle(handle, ctrl, NULL); > > list_for_each_entry(mapping, &ctrl->info.mappings, list) { > s32 value = __uvc_ctrl_get_value(mapping, data); > @@ -1863,7 +1898,7 @@ static int uvc_ctrl_commit_entity(struct uvc_device *dev, > > if (!rollback && handle && > ctrl->info.flags & UVC_CTRL_FLAG_ASYNCHRONOUS) > - ctrl->handle = handle; > + uvc_ctrl_set_handle(handle, ctrl, handle); > } > > return 0; > @@ -2772,6 +2807,25 @@ int uvc_ctrl_init_device(struct uvc_device *dev) > return 0; > } > > +void uvc_ctrl_cleanup_fh(struct uvc_fh *handle) > +{ > + struct uvc_entity *entity; > + > + guard(mutex)(&handle->chain->ctrl_mutex); > + > + if (!handle->pending_async_ctrls) > + return; > + > + list_for_each_entry(entity, &handle->chain->dev->entities, list) > + for (unsigned int i = 0; i < entity->ncontrols; ++i) { > + if (entity->controls[i].handle != handle) > + continue; > + uvc_ctrl_set_handle(handle, &entity->controls[i], NULL); > + } > + > + WARN_ON(handle->pending_async_ctrls); > +} > + > /* > * Cleanup device controls. > */ > diff --git a/drivers/media/usb/uvc/uvc_v4l2.c b/drivers/media/usb/uvc/uvc_v4l2.c > index 97c5407f6603..b425306a3b8c 100644 > --- a/drivers/media/usb/uvc/uvc_v4l2.c > +++ b/drivers/media/usb/uvc/uvc_v4l2.c > @@ -652,6 +652,8 @@ static int uvc_v4l2_release(struct file *file) > > uvc_dbg(stream->dev, CALLS, "%s\n", __func__); > > + uvc_ctrl_cleanup_fh(handle); > + > /* Only free resources if this is a privileged handle. */ > if (uvc_has_privileges(handle)) > uvc_queue_release(&stream->queue); > diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h > index 07f9921d83f2..92ecdd188587 100644 > --- a/drivers/media/usb/uvc/uvcvideo.h > +++ b/drivers/media/usb/uvc/uvcvideo.h > @@ -337,7 +337,11 @@ struct uvc_video_chain { > struct uvc_entity *processing; /* Processing unit */ > struct uvc_entity *selector; /* Selector unit */ > > - struct mutex ctrl_mutex; /* Protects ctrl.info */ > + struct mutex ctrl_mutex; /* > + * Protects ctrl.info, > + * ctrl.handle and > + * uvc_fh.pending_async_ctrls > + */ > > struct v4l2_prio_state prio; /* V4L2 priority state */ > u32 caps; /* V4L2 chain-wide caps */ > @@ -612,6 +616,7 @@ struct uvc_fh { > struct uvc_video_chain *chain; > struct uvc_streaming *stream; > enum uvc_handle_state state; > + unsigned int pending_async_ctrls; > }; > > struct uvc_driver { > @@ -797,6 +802,8 @@ int uvc_ctrl_is_accessible(struct uvc_video_chain *chain, u32 v4l2_id, > int uvc_xu_ctrl_query(struct uvc_video_chain *chain, > struct uvc_xu_control_query *xqry); > > +void uvc_ctrl_cleanup_fh(struct uvc_fh *handle); > + > /* Utility functions */ > struct usb_host_endpoint *uvc_find_endpoint(struct usb_host_interface *alts, > u8 epaddr); > > -- > 2.47.0.338.g60cca15819-goog >
This patchset fixes two +1 bugs with the async controls for the uvc driver. They were found while implementing the granular PM, but I am sending them as a separate patches, so they can be reviewed sooner. They fix real issues in the driver that need to be taken care. Signed-off-by: Ricardo Ribalda <ribalda@chromium.org> --- Changes in v6: - Swap order of patches - Use uvc_ctrl_set_handle again - Move loaded=0 to uvc_ctrl_status_event() - Link to v5: https://lore.kernel.org/r/20241202-uvc-fix-async-v5-0-6658c1fe312b@chromium.org Changes in v5: - Move set handle to the entity_commit - Replace uvc_ctrl_set_handle with get/put_handle. - Add a patch to flush the cache of async controls. - Link to v4: https://lore.kernel.org/r/20241129-uvc-fix-async-v4-0-f23784dba80f@chromium.org Changes in v4: - Fix implementation of uvc_ctrl_set_handle. - Link to v3: https://lore.kernel.org/r/20241129-uvc-fix-async-v3-0-ab675ce66db7@chromium.org Changes in v3: - change again! order of patches. - Introduce uvc_ctrl_set_handle. - Do not change ctrl->handle if it is not NULL. Changes in v2: - Annotate lockdep - ctrl->handle != handle - Change order of patches - Move documentation of mutex - Link to v1: https://lore.kernel.org/r/20241127-uvc-fix-async-v1-0-eb8722531b8c@chromium.org --- Ricardo Ribalda (5): media: uvcvideo: Only save async fh if success media: uvcvideo: Remove redundant NULL assignment media: uvcvideo: Remove dangling pointers media: uvcvideo: Annotate lock requirements for uvc_ctrl_set media: uvcvideo: Flush the control cache when we get an event drivers/media/usb/uvc/uvc_ctrl.c | 83 ++++++++++++++++++++++++++++++++++------ drivers/media/usb/uvc/uvc_v4l2.c | 2 + drivers/media/usb/uvc/uvcvideo.h | 9 ++++- 3 files changed, 82 insertions(+), 12 deletions(-) --- base-commit: 291a8d98186f0a704cb954855d2ae3233971f07d change-id: 20241127-uvc-fix-async-2c9d40413ad8 Best regards,