[PATCH v5 09/10] media: v4l2: Add DELETE_BUFS ioctl
Benjamin Gaignard
benjamin.gaignard at collabora.com
Fri Sep 1 05:32:58 PDT 2023
Le 30/08/2023 à 15:45, Hans Verkuil a écrit :
> On 24/08/2023 11:21, Benjamin Gaignard wrote:
>> VIDIOC_DELETE_BUFS ioctl allows to delete buffers from a queue.
>> The number of buffers to delete in given by count field of
>> struct v4l2_delete_buffers and the range start at the index
>> specified in the same structure.
>>
>> Signed-off-by: Benjamin Gaignard <benjamin.gaignard at collabora.com>
>> ---
>> .../userspace-api/media/v4l/user-func.rst | 1 +
>> .../media/v4l/vidioc-delete-bufs.rst | 73 +++++++++++++++++++
>> .../media/common/videobuf2/videobuf2-core.c | 34 +++++++++
>> .../media/common/videobuf2/videobuf2-v4l2.c | 16 ++++
>> drivers/media/v4l2-core/v4l2-dev.c | 1 +
>> drivers/media/v4l2-core/v4l2-ioctl.c | 17 +++++
>> include/media/v4l2-ioctl.h | 4 +
>> include/media/videobuf2-core.h | 9 +++
>> include/media/videobuf2-v4l2.h | 11 +++
>> include/uapi/linux/videodev2.h | 17 +++++
>> 10 files changed, 183 insertions(+)
>> create mode 100644 Documentation/userspace-api/media/v4l/vidioc-delete-bufs.rst
>>
>> diff --git a/Documentation/userspace-api/media/v4l/user-func.rst b/Documentation/userspace-api/media/v4l/user-func.rst
>> index 15ff0bf7bbe6..3fd567695477 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-bufs
>> vidioc-dqevent
>> vidioc-dv-timings-cap
>> vidioc-encoder-cmd
>> diff --git a/Documentation/userspace-api/media/v4l/vidioc-delete-bufs.rst b/Documentation/userspace-api/media/v4l/vidioc-delete-bufs.rst
>> new file mode 100644
>> index 000000000000..a55fe6331fc8
>> --- /dev/null
>> +++ b/Documentation/userspace-api/media/v4l/vidioc-delete-bufs.rst
>> @@ -0,0 +1,73 @@
>> +.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
>> +.. c:namespace:: V4L
>> +
>> +.. _VIDIOC_DELETE_BUFS:
>> +
>> +************************
>> +ioctl VIDIOC_DELETE_BUFS
>> +************************
>> +
>> +Name
>> +====
>> +
>> +VIDIOC_DELETE_BUFS - Deletes buffers from a queue
>> +
>> +Synopsis
>> +========
>> +
>> +.. c:macro:: VIDIOC_DELETE_BUFs
>> +
>> +``int ioctl(int fd, VIDIOC_DELETE_BUFs, struct v4l2_delete_buffers *argp)``
>> +
>> +Arguments
>> +=========
>> +
>> +``fd``
>> + File descriptor returned by :c:func:`open()`.
>> +
>> +``argp``
>> + Pointer to struct :c:type:`v4l2_delete_buffers`.
>> +
>> +Description
>> +===========
>> +
>> +Applications can optionally call the :ref:`VIDIOC_DELETE_BUFS` ioctl to
>> +delete buffers from a queue.
>> +
>> +.. c:type:: v4l2_delete_buffers
>> +
>> +.. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.5cm}|
>> +
>> +.. flat-table:: struct v4l2_delete_buffers
>> + :header-rows: 0
>> + :stub-columns: 0
>> + :widths: 1 1 2
>> +
>> + * - __u32
>> + - ``index``
>> + - The starting buffer index to delete.
>> + * - __u32
>> + - ``count``
>> + - The number of buffers to be deleted.
>> + * - __u32
>> + - ``type``
>> + - Type of the stream or buffers, this is the same as the struct
>> + :c:type:`v4l2_format` ``type`` field. See
>> + :c:type:`v4l2_buf_type` for valid values.
>> + * - __u32
>> + - ``reserved``\ [13]
>> + - A place holder for future extensions. Drivers and applications
>> + must set the array to zero.
>> +
>> +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 70e36389b704..3d915b4c33b2 100644
>> --- a/drivers/media/common/videobuf2/videobuf2-core.c
>> +++ b/drivers/media/common/videobuf2/videobuf2-core.c
>> @@ -1634,6 +1634,40 @@ 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)
> Same as the other core functions: rather than an index, pass a valid
> vb2_buffer pointer. Let the caller do the validation.
>
> My rule of thumb is that the core code should only need to call
> vb2_get_buffer() if it is walking over all buffers (i.e. in a
> for-loop). For functions like this it should get the vb pointer
> directly rather than having to look it up, since the caller
> should have done that already.
>
>> +{
>> + 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 buffer index %d\n", index);
>> + return -EINVAL;
>> + }
>> +
>> + 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);
>> + else if (q->memory == VB2_MEMORY_DMABUF)
>> + __vb2_buf_dmabuf_put(vb);
>> + else
>> + __vb2_buf_userptr_put(vb);
>> +
>> + vb2_queue_remove_buffer(q, vb);
> When freeing all buffers (REQBUFS with count=0) the q->mmap_lock is taken.
> I wonder if the same has to happen here. You don't want userspace to call mmap
> while deleting a buffer.
>
> I also think this should be refactored since __vb2_queue_free/__vb2_free_mem
> need to do the same thing.
>
>> + kfree(vb);
>> +
>> + dprintk(q, 2, "buffer %d deleted\n", index);
>> + return 0;
>> +}
>> +EXPORT_SYMBOL_GPL(vb2_core_delete_buf);
>> +
>> /*
>> * 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..ffe6b66a27f1 100644
>> --- a/drivers/media/common/videobuf2/videobuf2-v4l2.c
>> +++ b/drivers/media/common/videobuf2/videobuf2-v4l2.c
>> @@ -751,6 +751,22 @@ int vb2_prepare_buf(struct vb2_queue *q, struct media_device *mdev,
>> }
>> EXPORT_SYMBOL_GPL(vb2_prepare_buf);
>>
>> +int vb2_delete_bufs(struct vb2_queue *q, struct v4l2_delete_buffers *d)
>> +{
>> + unsigned int index;
>> + int ret = 0;
>> +
> Add a check if index < q->num_buffers, count < q->num_buffers and that
> the sum of the two <= q->num_buffers. I.e., basic sanity checks.
>
> Return -EINVAL if that's the case.
>
>> + for (index = d->index; index < d->index + d->count; index++) {
>> + ret = vb2_core_delete_buf(q, index);
>> + if (ret)
>> + break;
>> + }
>> +
>> + d->index = index;
> Hmm. I wonder if vb2_core_delete_buf shouldn't be void, and instead
> verify here first that all buffers your want to delete 1) exist, and
> 2) are in state DEQUEUED.
I will keep using vb2_core_delete_buf() because it use static functions videobuf2-core.c
and I don't want to change all of them.
>
>> + return ret;
>> +}
>> +EXPORT_SYMBOL_GPL(vb2_delete_bufs);
>> +
>> 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..215654fd6581 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_BUFS, vidioc_delete_bufs);
>> }
>>
>> 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 f4d9d6279094..32336b9bb7e4 100644
>> --- a/drivers/media/v4l2-core/v4l2-ioctl.c
>> +++ b/drivers/media/v4l2-core/v4l2-ioctl.c
>> @@ -489,6 +489,13 @@ static void v4l_print_create_buffers(const void *arg, bool write_only)
>> v4l_print_format(&p->format, write_only);
>> }
>>
>> +static void v4l_print_delete_buffers(const void *arg, bool write_only)
>> +{
>> + const struct v4l2_delete_buffers *p = arg;
>> +
>> + pr_cont("index=%d, count=%d\n", p->index, p->count);
>> +}
>> +
>> static void v4l_print_streamparm(const void *arg, bool write_only)
>> {
>> const struct v4l2_streamparm *p = arg;
>> @@ -2160,6 +2167,15 @@ 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_bufs(const struct v4l2_ioctl_ops *ops,
>> + struct file *file, void *fh, void *arg)
>> +{
>> + struct v4l2_delete_buffers *delete = arg;
>> + int ret = check_fmt(file, delete->type);
>> +
>> + return ret ? ret : ops->vidioc_delete_bufs(file, fh, delete);
>> +}
>> +
>> static int v4l_g_parm(const struct v4l2_ioctl_ops *ops,
>> struct file *file, void *fh, void *arg)
>> {
>> @@ -2909,6 +2925,7 @@ 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_BUFS, v4l_delete_bufs, v4l_print_delete_buffers, INFO_FL_QUEUE),
> You can add INFO_FL_CLEAR here to automatically zero the reserved field. It also needs INFO_FL_PRIO.
>
>> };
>> #define V4L2_IOCTLS ARRAY_SIZE(v4l2_ioctls)
>>
>> diff --git a/include/media/v4l2-ioctl.h b/include/media/v4l2-ioctl.h
>> index edb733f21604..55afbde54211 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_bufs: pointer to the function that implements
>> + * :ref:`VIDIOC_DELETE_BUFS <vidioc_delete_bufs>` 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_bufs)(struct file *file, void *fh,
>> + struct v4l2_delete_buffers *d);
>>
>> 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 ee9161b9fd64..c9ecc4214982 100644
>> --- a/include/media/videobuf2-core.h
>> +++ b/include/media/videobuf2-core.h
>> @@ -843,6 +843,15 @@ 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 5a845887850b..2ef68fdf388f 100644
>> --- a/include/media/videobuf2-v4l2.h
>> +++ b/include/media/videobuf2-v4l2.h
>> @@ -118,6 +118,17 @@ 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_bufs() - Delete buffers from the queue
>> + *
>> + * @q: pointer to &struct vb2_queue with videobuf2 queue.
>> + * @d: delete parameter, passed from userspace to
>> + * &v4l2_ioctl_ops->vidioc_delete_bufs handler in driver
>> + *
>> + * The return values from this function are intended to be directly returned
>> + * from &v4l2_ioctl_ops->vidioc_delete_bufs handler in driver.
>> + */
>> +int vb2_delete_bufs(struct vb2_queue *q, struct v4l2_delete_buffers *d);
>>
>> /**
>> * vb2_qbuf() - Queue a buffer from userspace
>> diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h
>> index 78260e5d9985..4807b38e2a6f 100644
>> --- a/include/uapi/linux/videodev2.h
>> +++ b/include/uapi/linux/videodev2.h
>> @@ -2616,6 +2616,21 @@ struct v4l2_create_buffers {
>> __u32 reserved[6];
>> };
>>
>> +/**
>> + * struct v4l2_delete_buffers - VIDIOC_DELETE_BUFS argument
>> + * @index: the first buffer to be deleted
>> + * @count: number of buffers to delete
>> + * @type: enum v4l2_buf_type; buffer type (type == *_MPLANE for
>> + * multiplanar buffers);
> I would drop the bit between (). That seems overkill to me.
>
>> + * @reserved: futur extensions
> futur -> future
>
>> + */
>> +struct v4l2_delete_buffers {
>> + __u32 index;
>> + __u32 count;
>> + __u32 type;
>> + __u32 reserved[13];
>> +};
>> +
>> /*
>> * I O C T L C O D E S F O R V I D E O D E V I C E S
>> *
>> @@ -2715,6 +2730,8 @@ 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_BUFS _IOWR('V', 104, struct v4l2_delete_buffers)
>> +
>>
>> /* Reminder: when adding new ioctls please add support for them to
>> drivers/media/v4l2-core/v4l2-compat-ioctl32.c as well! */
> Regards,
>
> Hans
>
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