diff mbox series

[v2,5/8] media: v4l2: Add DELETE_BUF ioctl

Message ID 20230321102855.346732-6-benjamin.gaignard@collabora.com
State New
Headers show
Series Add DELETE_BUF ioctl | expand

Commit Message

Benjamin Gaignard March 21, 2023, 10:28 a.m. UTC 
VIDIOC_DELETE_BUF ioctl allows to delete a buffer from a queue.

Signed-off-by: Benjamin Gaignard <benjamin.gaignard@collabora.com>
---
 .../userspace-api/media/v4l/user-func.rst     |  1 +
 .../media/v4l/vidioc-delete-buf.rst           | 51 ++++++++++++++++
 .../media/common/videobuf2/videobuf2-core.c   | 59 ++++++++++++++++++-
 .../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                |  1 +
 10 files changed, 152 insertions(+), 1 deletion(-)
 create mode 100644 Documentation/userspace-api/media/v4l/vidioc-delete-buf.rst

Comments

Tomasz Figa May 23, 2023, 8:23 a.m. UTC | #1 
On Tue, Mar 21, 2023 at 11:28:52AM +0100, Benjamin Gaignard wrote:
> VIDIOC_DELETE_BUF ioctl allows to delete a buffer from a queue.
> 
> Signed-off-by: Benjamin Gaignard <benjamin.gaignard@collabora.com>
> ---
>  .../userspace-api/media/v4l/user-func.rst     |  1 +
>  .../media/v4l/vidioc-delete-buf.rst           | 51 ++++++++++++++++
>  .../media/common/videobuf2/videobuf2-core.c   | 59 ++++++++++++++++++-
>  .../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                |  1 +
>  10 files changed, 152 insertions(+), 1 deletion(-)
>  create mode 100644 Documentation/userspace-api/media/v4l/vidioc-delete-buf.rst
> 
> diff --git a/Documentation/userspace-api/media/v4l/user-func.rst b/Documentation/userspace-api/media/v4l/user-func.rst
> index 228c1521f190..93e0a6a117fc 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`.

Would struct v4l2_create_buffers make more sense here? With it, we could
actually make this ioctl VIDIOC_DELETE_BUF*S*, consistently with
VIDIOC_CREATE_BUF*S* and allow the user space to remove a block of buffers
the same way it created a block of buffers in the first place.

> +
> +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 3c6ced360770..ec241d726fe6 100644
> --- a/drivers/media/common/videobuf2/videobuf2-core.c
> +++ b/drivers/media/common/videobuf2/videobuf2-core.c
> @@ -401,6 +401,24 @@ static void init_buffer_cache_hints(struct vb2_queue *q, struct vb2_buffer *vb)
>  		vb->skip_cache_sync_on_finish = 1;
>  }
>  
> +/*
> + * __vb2_queue_get_free_index() - find a free index in the queue for vb2 buffer.
> + *
> + * Returns an index for vb2 buffer.
> + */
> +static int __vb2_queue_get_free_index(struct vb2_queue *q)
> +{
> +	int i;
> +
> +	spin_lock(&q->bufs_lock);
> +	for (i = 0; i < q->max_num_bufs; i++)
> +		if (!q->bufs[i])
> +			break;
> +	spin_unlock(&q->bufs_lock);
> +
> +	return i;
> +}

Another reason to go with XArray, so that we don't have to open code
index reclaim.

> +
>  /*
>   * __vb2_queue_alloc() - allocate vb2 buffer structures and (for MMAP type)
>   * video buffer memory for all buffers/planes on the queue and initializes the
> @@ -427,7 +445,7 @@ static int __vb2_queue_alloc(struct vb2_queue *q, enum vb2_memory memory,
>  		vb->state = VB2_BUF_STATE_DEQUEUED;
>  		vb->vb2_queue = q;
>  		vb->num_planes = num_planes;
> -		vb->index = q->num_buffers + buffer;
> +		vb->index = __vb2_queue_get_free_index(q);
>  		vb->type = q->type;
>  		vb->memory = memory;
>  		init_buffer_cache_hints(q, vb);
> @@ -1570,6 +1588,45 @@ 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_QUEUED) {

How about other states? I'd probably only allow this when the state is
DEQUEUED for simplicity. Is there a need to allow deleting buffers in
other states?

Also, do we need to synchronize this with other contexts which could change
the buffer state?

> +		dprintk(q, 1, "can't delete queued buffer index %d\n", index);
> +		return -EINVAL;
> +	}
> +

Don't we also need to hold q->mmap_lock to prevent racing with an attempt
to mmap the buffer?

> +	if (vb && vb->planes[0].mem_priv)

nit: At this point it's not possible for vb to be NULL, since we already
ruled that out a few lines above.

> +		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);
> +	kfree(vb);
> +
> +	q->num_buffers--;
> +	if (!q->num_buffers) {
> +		q->memory = VB2_MEMORY_UNKNOWN;
> +		INIT_LIST_HEAD(&q->queued_list);
> +	}

Would it make sense to refactor __vb2_queue_free() instead to take a
range of buffer indexes rather than duplicating the code here?

Best regards,
Tomasz
diff mbox series

Patch

diff --git a/Documentation/userspace-api/media/v4l/user-func.rst b/Documentation/userspace-api/media/v4l/user-func.rst
index 228c1521f190..93e0a6a117fc 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 3c6ced360770..ec241d726fe6 100644
--- a/drivers/media/common/videobuf2/videobuf2-core.c
+++ b/drivers/media/common/videobuf2/videobuf2-core.c
@@ -401,6 +401,24 @@  static void init_buffer_cache_hints(struct vb2_queue *q, struct vb2_buffer *vb)
 		vb->skip_cache_sync_on_finish = 1;
 }
 
+/*
+ * __vb2_queue_get_free_index() - find a free index in the queue for vb2 buffer.
+ *
+ * Returns an index for vb2 buffer.
+ */
+static int __vb2_queue_get_free_index(struct vb2_queue *q)
+{
+	int i;
+
+	spin_lock(&q->bufs_lock);
+	for (i = 0; i < q->max_num_bufs; i++)
+		if (!q->bufs[i])
+			break;
+	spin_unlock(&q->bufs_lock);
+
+	return i;
+}
+
 /*
  * __vb2_queue_alloc() - allocate vb2 buffer structures and (for MMAP type)
  * video buffer memory for all buffers/planes on the queue and initializes the
@@ -427,7 +445,7 @@  static int __vb2_queue_alloc(struct vb2_queue *q, enum vb2_memory memory,
 		vb->state = VB2_BUF_STATE_DEQUEUED;
 		vb->vb2_queue = q;
 		vb->num_planes = num_planes;
-		vb->index = q->num_buffers + buffer;
+		vb->index = __vb2_queue_get_free_index(q);
 		vb->type = q->type;
 		vb->memory = memory;
 		init_buffer_cache_hints(q, vb);
@@ -1570,6 +1588,45 @@  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_QUEUED) {
+		dprintk(q, 1, "can't delete queued buffer index %d\n", index);
+		return -EINVAL;
+	}
+
+	if (vb && 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);
+	kfree(vb);
+
+	q->num_buffers--;
+	if (!q->num_buffers) {
+		q->memory = VB2_MEMORY_UNKNOWN;
+		INIT_LIST_HEAD(&q->queued_list);
+	}
+
+	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 01b2bb957239..7d0b4ed48a06 100644
--- a/drivers/media/common/videobuf2/videobuf2-v4l2.c
+++ b/drivers/media/common/videobuf2/videobuf2-v4l2.c
@@ -742,6 +742,12 @@  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 397d553177fa..4f49d2115838 100644
--- a/drivers/media/v4l2-core/v4l2-dev.c
+++ b/drivers/media/v4l2-core/v4l2-dev.c
@@ -719,6 +719,7 @@  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 87f163a89c80..2e0af50cac45 100644
--- a/drivers/media/v4l2-core/v4l2-ioctl.c
+++ b/drivers/media/v4l2-core/v4l2-ioctl.c
@@ -2152,6 +2152,15 @@  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)
 {
@@ -2902,6 +2911,7 @@  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 4aa43c5c7c58..16e95278f6e8 100644
--- a/include/media/videobuf2-core.h
+++ b/include/media/videobuf2-core.h
@@ -847,6 +847,15 @@  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 17a9b975177a..9cee9ccf1da8 100644
--- a/include/uapi/linux/videodev2.h
+++ b/include/uapi/linux/videodev2.h
@@ -2681,6 +2681,7 @@  struct v4l2_create_buffers {
 #define VIDIOC_QUERY_DV_TIMINGS  _IOR('V', 99, struct v4l2_dv_timings)
 #define VIDIOC_DV_TIMINGS_CAP   _IOWR('V', 100, struct v4l2_dv_timings_cap)
 #define VIDIOC_ENUM_FREQ_BANDS	_IOWR('V', 101, struct v4l2_frequency_band)
+#define VIDIOC_DELETE_BUF	_IOWR('V', 102, struct v4l2_buffer)
 
 /*
  * Experimental, meant for debugging, testing and internal use.