On 2023/7/3 19:17, Benjamin Gaignard wrote:
Le 03/07/2023 à 13:02, Hsia-Jun Li a écrit :Of course if the application delete a useful buffer it is a problem but an application issue.On 7/3/23 18:35, Benjamin Gaignard wrote:CAUTION: Email originated externally, do not click links or open attachments unless you recognize the sender and know the content is safe.Le 03/07/2023 à 11:20, Hsia-Jun Li a écrit :On 7/3/23 16:52, Benjamin Gaignard wrote:CAUTION: Email originated externally, do not click links or open attachments unless you recognize the sender and know the content is safe. Le 03/07/2023 à 10:19, Hsia-Jun Li a écrit :On 7/3/23 16:12, Benjamin Gaignard wrote:CAUTION: Email originated externally, do not click links or open attachments unless you recognize the sender and know the content is safe. Le 30/06/2023 à 11:43, Hsia-Jun Li a écrit :On 6/27/23 16:47, Hsia-Jun Li wrote:CAUTION: Email originated externally, do not click links or openattachments unless you recognize the sender and know the content issafe. On 6/27/23 16:43, Benjamin Gaignard wrote:CAUTION: Email originated externally, do not click links or openattachments unless you recognize the sender and know the content issafe. Le 27/06/2023 à 09:30, Hsia-Jun Li a écrit :On 6/22/23 21:13, Benjamin Gaignard wrote:CAUTION: Email originated externally, do not click links or openattachments unless you recognize the sender and know the content is safe.VIDIOC_DELETE_BUF ioctl allows to delete a buffer from a queue.Signed-off-by: Benjamin Gaignard <benjamin.gaignard@xxxxxxxxxxxxx> --- .../userspace-api/media/v4l/user-func.rst | 1 + .../media/v4l/vidioc-delete-buf.rst | 51 +++++++++++++++++++ .../media/common/videobuf2/videobuf2-core.c | 33 ++++++++++++ .../media/common/videobuf2/videobuf2-v4l2.c | 6 +++ drivers/media/v4l2-core/v4l2-dev.c | 1 + drivers/media/v4l2-core/v4l2-ioctl.c | 10 ++++ include/media/v4l2-ioctl.h | 4 ++ include/media/videobuf2-core.h | 9 ++++ include/media/videobuf2-v4l2.h | 11 ++++ include/uapi/linux/videodev2.h | 2 + 10 files changed, 128 insertions(+) create mode 100644 Documentation/userspace-api/media/v4l/vidioc-delete-buf.rstdiff --git a/Documentation/userspace-api/media/v4l/user-func.rstb/Documentation/userspace-api/media/v4l/user-func.rst index 15ff0bf7bbe6..8c74016e12fd 100644 --- a/Documentation/userspace-api/media/v4l/user-func.rst +++ b/Documentation/userspace-api/media/v4l/user-func.rst @@ -17,6 +17,7 @@ Function Reference vidioc-dbg-g-chip-info vidioc-dbg-g-register vidioc-decoder-cmd + vidioc-delete-buf vidioc-dqevent vidioc-dv-timings-cap vidioc-encoder-cmd diff --git a/Documentation/userspace-api/media/v4l/vidioc-delete-buf.rst b/Documentation/userspace-api/media/v4l/vidioc-delete-buf.rst new file mode 100644 index 000000000000..0e7ce58f91bc --- /dev/null+++ b/Documentation/userspace-api/media/v4l/vidioc-delete-buf.rst@@ -0,0 +1,51 @@ +.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later +.. c:namespace:: V4L + +.. _VIDIOC_DELETE_BUF: + +************************ +ioctl VIDIOC_DELETE_BUF +************************ + +Name +==== + +VIDIOC_DELETE_BUF - Delete a buffer from a queue + +Synopsis +======== + +.. c:macro:: VIDIOC_DELETE_BUF + +``int ioctl(int fd, VIDIOC_DELETE_BUF, struct v4l2_buffer *argp)`` + +Arguments +========= + +``fd`` + File descriptor returned by :c:func:`open()`. + +``argp`` + Pointer to struct :c:type:`v4l2_buffer`. + +Description +=========== + +Applications can optionally call the :ref:`VIDIOC_DELETE_BUF` ioctl to +delete a buffer from a queue. + +The struct :c:type:`v4l2_buffer` structure is specified in +:ref:`buffer`. + +Return Value +============ + +On success 0 is returned, on error -1 and the ``errno`` variable is set +appropriately. The generic error codes are described at the +:ref:`Generic Error Codes <gen-errors>` chapter. + +EBUSY + File I/O is in progress. + +EINVAL + The buffer ``index`` doesn't exist in the queue. diff --git a/drivers/media/common/videobuf2/videobuf2-core.c b/drivers/media/common/videobuf2/videobuf2-core.c index 899783f67580..aa546c972c3d 100644 --- a/drivers/media/common/videobuf2/videobuf2-core.c +++ b/drivers/media/common/videobuf2/videobuf2-core.c@@ -1637,6 +1637,39 @@ int vb2_core_prepare_buf(struct vb2_queue*q, unsigned int index, void *pb) } EXPORT_SYMBOL_GPL(vb2_core_prepare_buf);+int vb2_core_delete_buf(struct vb2_queue *q, unsigned int index)+{ + struct vb2_buffer *vb; + + vb = vb2_get_buffer(q, index); + if (!vb) { + dprintk(q, 1, "invalid buffer index %d\n", index); + return -EINVAL; + } + + if (vb->state != VB2_BUF_STATE_DEQUEUED) {+ dprintk(q, 1, "can't delete non dequeued bufferindex %d\n", index); + return -EINVAL; + } +I know the driver could implement its ownv4l2_ioctl_ops->vidioc_delete_buf() that check whether a buffer isused by the hardware as a future reference frame. But I think we need a flag to let the user know which buffer is still used by the hardware. Alternative ref case is safe, we only know it's existing when it is dequeued in current V4L2 buffer mechanism.While the Golden reference frame, such long term reference framecould last much longer.It is up to userland stack to know frames life time, it got the information for that.That is true for the stateless codec driver.While application for stateful decoder could never do that. It alsobreaks what the document said:"The backing memory of |CAPTURE| buffers that are used as reference frames by the stream may be read by the hardware even after they aredequeued. Consequently, the client should avoid writing into this memorywhile the |CAPTURE| queue is streaming. Failure to observe this mayresult in corruption of decoded frames."+ if (vb->planes[0].mem_priv) + call_void_vb_qop(vb, buf_cleanup, vb); + + /* Free MMAP buffers or release USERPTR buffers */ + if (q->memory == VB2_MEMORY_MMAP) + __vb2_buf_mem_free(vb);Here is another problem for the existing application, the mmap() fromthe mmap offset or exportbuffer fd would not create a reference tobuffer in this step(while the exportbuffer would create one itself).When you delete a buffer, you may not release it from its virtual memory space, leaving a corrupted virtual memory space. Also this behavior is right, because mmap(2) says:"After the mmap() call has returned, the file descriptor, fd, canbe closed immediately without invalidating the map‐ping."Existing applications do not call DELETE_BUF ioctl and when call it they will be aware that the buffer is removed. I have done it in GStreamer:https://urldefense.proofpoint.com/v2/url?u=https-3A__gitlab.freedesktop.org_benjamin.gaignard1_gstreamer_-2D_commit_fca0fbc934f4440693ce0ff6c8dc8a2e5f5f17d9&d=DwIDaQ&c=7dfBJ8cXbWjhc0BhImu8wVIoUFmBzj1s88r8EGyM0UY&r=P4xb2_7biqBxD4LGGPrSV6j-jf3C3xlR7PXU-mLTeZE&m=TGH9toTzGRfO5aBsfaMvGbcOw-28q6cPmpX6vScbHjpCtaLtb-RuvBvsJ0z9RvAB&s=Ufl1ccfRZf2EhnfCBvnQzRJV9CDhGxl5spe9WNECspU&e=I have read that.There is not a VP8 parser in Gstreamer, while a parser would not workwhen deal with the secure video(userspace can't access the data context at all).Besides, this adds extra work for the application for a stateful codec driver. The application need to parser the bitstream and track the dpb.I don't mind if you could fix the nonfiction mechanism for those non-display frame and internal reference state. That could be requirement for codec firmware that its driver could support this DELETE_BUF ioctl() feature.Sorry I don't see the link with my patches here... I have work on non-secure VP9 on stateless codec. DELETE_BUF ioctl is optional and the main goal is to offer a way to applicationsto save memory if they know when they could delete buffers without risk.I try to explain why I think this design in not "complete". One problem resolved, more problems would occur. For non-secure video, those applications have worked: - It would break what stateful means here, application need to acquire(parse) the information that driver should offer. Or it would break the decoding model. - Your Gstreamer sample code or this design won't work for AV1.why ?A frame in AV1 could be put to display order with a future frame. That is quite different to those ITU codecs.Supposing a frame (we call it frame 0) without show_display frame, you could delete it (just want to do that) once it is decoded.Actually, unless 7 future frames have came and parser has acknowledged them, it is not safe to delete that frame.Or a show_exist that make frame 0 present.In my personal opinion, this feature could break many uAPI's, I have said my worrying in the other emails.
I don't think this feature is only applied to stateless codec. Stateful codec could reclaim the previous memory as well.
The implementation now just leave all those problems to the conscience of the application, no protection from the kernel which could crash the hardware easily.
I am not against on this feature, I just wish it would be more safe and more complete.
I have test this code using GStreamer with VP9, VP8 and HEVC on Verisilicon driver without issues.
Even with the secure decoding, at least someone should offer the DPB info or we just don't need this.
I am sure stateless decoder could work well with that despite the performance impact on buffer looking up.
I will be happy if someone could test it on another driver and/or other userlands (like ffmpeg).For all the future possible secure video: - This feature could never be used from the current design.Regards, Benjamin+ else if (q->memory == VB2_MEMORY_DMABUF) + __vb2_buf_dmabuf_put(vb); + else + __vb2_buf_userptr_put(vb); + + vb2_queue_remove_buffer(q, vb); + kfree(vb); + + dprintk(q, 2, "buffer %d deleted\n", index); + return 0; +} + /* * vb2_start_streaming() - Attempt to start streaming. * @q: videobuf2 queue diff --git a/drivers/media/common/videobuf2/videobuf2-v4l2.c b/drivers/media/common/videobuf2/videobuf2-v4l2.c index 724135d41f7f..cea666c17b41 100644 --- a/drivers/media/common/videobuf2/videobuf2-v4l2.c +++ b/drivers/media/common/videobuf2/videobuf2-v4l2.c @@ -751,6 +751,12 @@ int vb2_prepare_buf(struct vb2_queue *q, struct media_device *mdev, } EXPORT_SYMBOL_GPL(vb2_prepare_buf);+int vb2_delete_buf(struct vb2_queue *q, struct v4l2_buffer *b)+{ + return vb2_core_delete_buf(q, b->index); +} +EXPORT_SYMBOL_GPL(vb2_delete_buf); + int vb2_create_bufs(struct vb2_queue *q, struct v4l2_create_buffers *create) { unsigned requested_planes = 1; diff --git a/drivers/media/v4l2-core/v4l2-dev.c b/drivers/media/v4l2-core/v4l2-dev.c index f81279492682..80ace2e1e932 100644 --- a/drivers/media/v4l2-core/v4l2-dev.c +++ b/drivers/media/v4l2-core/v4l2-dev.c @@ -720,6 +720,7 @@ static void determine_valid_ioctls(struct video_device *vdev) SET_VALID_IOCTL(ops, VIDIOC_PREPARE_BUF, vidioc_prepare_buf); SET_VALID_IOCTL(ops, VIDIOC_STREAMON, vidioc_streamon); SET_VALID_IOCTL(ops, VIDIOC_STREAMOFF, vidioc_streamoff); + SET_VALID_IOCTL(ops, VIDIOC_DELETE_BUF, vidioc_delete_buf); } if (is_vid || is_vbi || is_meta) { diff --git a/drivers/media/v4l2-core/v4l2-ioctl.c b/drivers/media/v4l2-core/v4l2-ioctl.c index a858acea6547..1c737279d3ef 100644 --- a/drivers/media/v4l2-core/v4l2-ioctl.c +++ b/drivers/media/v4l2-core/v4l2-ioctl.c @@ -2156,6 +2156,15 @@ static int v4l_prepare_buf(const struct v4l2_ioctl_ops *ops,return ret ? ret : ops->vidioc_prepare_buf(file, fh, b);} +static int v4l_delete_buf(const struct v4l2_ioctl_ops *ops,+ struct file *file, void *fh, void *arg)+{ + struct v4l2_buffer *b = arg; + int ret = check_fmt(file, b->type); ++ return ret ? ret : ops->vidioc_delete_buf(file, fh, b);+} + static int v4l_g_parm(const struct v4l2_ioctl_ops *ops, struct file *file, void *fh, void *arg) { @@ -2905,6 +2914,7 @@ static const struct v4l2_ioctl_info v4l2_ioctls[] = {IOCTL_INFO(VIDIOC_ENUM_FREQ_BANDS, v4l_enum_freq_bands,v4l_print_freq_band, 0),IOCTL_INFO(VIDIOC_DBG_G_CHIP_INFO, v4l_dbg_g_chip_info,v4l_print_dbg_chip_info, INFO_FL_CLEAR(v4l2_dbg_chip_info, match)), IOCTL_INFO(VIDIOC_QUERY_EXT_CTRL, v4l_query_ext_ctrl, v4l_print_query_ext_ctrl, INFO_FL_CTRL | INFO_FL_CLEAR(v4l2_query_ext_ctrl, id)), + IOCTL_INFO(VIDIOC_DELETE_BUF, v4l_delete_buf, v4l_print_buffer, INFO_FL_QUEUE), }; #define V4L2_IOCTLS ARRAY_SIZE(v4l2_ioctls) diff --git a/include/media/v4l2-ioctl.h b/include/media/v4l2-ioctl.h index edb733f21604..2f232ed884c7 100644 --- a/include/media/v4l2-ioctl.h +++ b/include/media/v4l2-ioctl.h @@ -163,6 +163,8 @@ struct v4l2_fh; * :ref:`VIDIOC_CREATE_BUFS <vidioc_create_bufs>` ioctl* @vidioc_prepare_buf: pointer to the function that implements* :ref:`VIDIOC_PREPARE_BUF <vidioc_prepare_buf>` ioctl+ * @vidioc_delete_buf: pointer to the function that implements+ * :ref:`VIDIOC_DELETE_BUF <vidioc_delete_buf>` ioctl * @vidioc_overlay: pointer to the function that implements * :ref:`VIDIOC_OVERLAY <vidioc_overlay>` ioctl * @vidioc_g_fbuf: pointer to the function that implements @@ -422,6 +424,8 @@ struct v4l2_ioctl_ops { struct v4l2_create_buffers *b);int (*vidioc_prepare_buf)(struct file *file, void *fh,struct v4l2_buffer *b); + int (*vidioc_delete_buf)(struct file *file, void *fh, + struct v4l2_buffer *b); int (*vidioc_overlay)(struct file *file, void *fh, unsigned int i); int (*vidioc_g_fbuf)(struct file *file, void *fh, diff --git a/include/media/videobuf2-core.h b/include/media/videobuf2-core.h index 080b783d608d..0f9e68f76b77 100644 --- a/include/media/videobuf2-core.h +++ b/include/media/videobuf2-core.h @@ -840,6 +840,15 @@ int vb2_core_create_bufs(struct vb2_queue *q, enum vb2_memory memory, */ int vb2_core_prepare_buf(struct vb2_queue *q, unsigned int index, void *pb); +/** + * vb2_core_delete_buf() - + * @q: pointer to &struct vb2_queue with videobuf2 queue. + * @index: id number of the buffer. + * + * Return: returns zero on success; an error code otherwise. + */ +int vb2_core_delete_buf(struct vb2_queue *q, unsigned int index); + /** * vb2_core_qbuf() - Queue a buffer from userspace * diff --git a/include/media/videobuf2-v4l2.h b/include/media/videobuf2-v4l2.h index 88a7a565170e..3beeb4c735f0 100644 --- a/include/media/videobuf2-v4l2.h +++ b/include/media/videobuf2-v4l2.h @@ -114,6 +114,17 @@ int vb2_create_bufs(struct vb2_queue *q, struct v4l2_create_buffers *create); */ int vb2_prepare_buf(struct vb2_queue *q, struct media_device *mdev, struct v4l2_buffer *b); +/** + * vb2_delete_buf() - Delete the buffer from the queue + * + * @q: pointer to &struct vb2_queue with videobuf2 queue. + * @b: buffer structure passed from userspace to + * &v4l2_ioctl_ops->vidioc_delete_buf handler in driver + * + * The return values from this function are intended to be directly returned + * from &v4l2_ioctl_ops->vidioc_delete_buf handler in driver. + */+int vb2_delete_buf(struct vb2_queue *q, struct v4l2_buffer *b);/** * vb2_qbuf() - Queue a buffer from userspace diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h index aee75eb9e686..31bba1915642 100644 --- a/include/uapi/linux/videodev2.h +++ b/include/uapi/linux/videodev2.h @@ -2702,6 +2702,8 @@ struct v4l2_create_buffers { #define VIDIOC_DBG_G_CHIP_INFO _IOWR('V', 102, struct v4l2_dbg_chip_info) #define VIDIOC_QUERY_EXT_CTRL _IOWR('V', 103, struct v4l2_query_ext_ctrl) +#define VIDIOC_DELETE_BUF _IOWR('V', 104, struct v4l2_buffer) + /* Reminder: when adding new ioctls please add support for them to drivers/media/v4l2-core/v4l2-compat-ioctl32.c as well! */ -- 2.39.2-- Hsia-Jun(Randy) Li-- Hsia-Jun(Randy) Li
