media: v4l2: Add REMOVE_BUFS ioctl

VIDIOC_REMOVE_BUFS ioctl allows to remove buffers from a queue.
The number of buffers to remove in given by count field of
struct v4l2_remove_buffers and the range start at the index
specified in the same structure.

Signed-off-by: Benjamin Gaignard <benjamin.gaignard@collabora.com>
Reviewed-by: Mauro Carvalho Chehab <mchehab@kernel.org>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
[hverkuil: vidioc-remove-bufs.rst: mention no bufs are freed on error]

2 files changed, 57 insertions, 1 deletions

diff --git a/drivers/media/common/videobuf2/videobuf2-core.c b/drivers/media/common/videobuf2/videobuf2-core.c
index 009cea95d662..0b2b48e1b2df 100644
--- a/drivers/media/common/videobuf2/videobuf2-core.c
+++ b/drivers/media/common/videobuf2/videobuf2-core.c
@@ -1691,6 +1691,44 @@ int vb2_core_prepare_buf(struct vb2_queue *q, struct vb2_buffer *vb, void *pb)
 }
 EXPORT_SYMBOL_GPL(vb2_core_prepare_buf);
 
+int vb2_core_remove_bufs(struct vb2_queue *q, unsigned int start, unsigned int count)
+{
+	unsigned int i, ret = 0;
+	unsigned int q_num_bufs = vb2_get_num_buffers(q);
+
+	if (count == 0)
+		return 0;
+
+	if (count > q_num_bufs)
+		return -EINVAL;
+
+	if (start > q->max_num_buffers - count)
+		return -EINVAL;
+
+	mutex_lock(&q->mmap_lock);
+
+	/* Check that all buffers in the range exist */
+	for (i = start; i < start + count; i++) {
+		struct vb2_buffer *vb = vb2_get_buffer(q, i);
+
+		if (!vb) {
+			ret = -EINVAL;
+			goto unlock;
+		}
+		if (vb->state != VB2_BUF_STATE_DEQUEUED) {
+			ret = -EBUSY;
+			goto unlock;
+		}
+	}
+	__vb2_queue_free(q, start, count);
+	dprintk(q, 2, "%u buffers removed\n", count);
+
+unlock:
+	mutex_unlock(&q->mmap_lock);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(vb2_core_remove_bufs);
+
 /*
  * 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 03e8080a68a8..293f3d5f1c4e 100644
--- a/drivers/media/common/videobuf2/videobuf2-v4l2.c
+++ b/drivers/media/common/videobuf2/videobuf2-v4l2.c
@@ -685,7 +685,7 @@ static void vb2_set_flags_and_caps(struct vb2_queue *q, u32 memory,
 		*flags &= V4L2_MEMORY_FLAG_NON_COHERENT;
 	}
 
-	*caps = V4L2_BUF_CAP_SUPPORTS_ORPHANED_BUFS;
+	*caps |= V4L2_BUF_CAP_SUPPORTS_ORPHANED_BUFS;
 	if (q->io_modes & VB2_MMAP)
 		*caps |= V4L2_BUF_CAP_SUPPORTS_MMAP;
 	if (q->io_modes & VB2_USERPTR)
@@ -1001,6 +1001,24 @@ EXPORT_SYMBOL_GPL(vb2_poll);
 
 /* vb2 ioctl helpers */
 
+int vb2_ioctl_remove_bufs(struct file *file, void *priv,
+			  struct v4l2_remove_buffers *d)
+{
+	struct video_device *vdev = video_devdata(file);
+
+	if (vdev->queue->type != d->type)
+		return -EINVAL;
+
+	if (d->count == 0)
+		return 0;
+
+	if (vb2_queue_is_busy(vdev->queue, file))
+		return -EBUSY;
+
+	return vb2_core_remove_bufs(vdev->queue, d->index, d->count);
+}
+EXPORT_SYMBOL_GPL(vb2_ioctl_remove_bufs);
+
 int vb2_ioctl_reqbufs(struct file *file, void *priv,
 			  struct v4l2_requestbuffers *p)
 {