media: v4l2-mem2mem: Apply DST_QUEUE_OFF_BASE on MMAP buffers across ioctls

BugLink: https://bugs.launchpad.net/bugs/1989230

commit 8310ca9 upstream.

DST_QUEUE_OFF_BASE is applied to offset/mem_offset on MMAP capture buffers
only for the VIDIOC_QUERYBUF ioctl, while the userspace fields (including
offset/mem_offset) are filled in for VIDIOC_{QUERY,PREPARE,Q,DQ}BUF
ioctls. This leads to differences in the values presented to userspace.
If userspace attempts to mmap the capture buffer directly using values
from DQBUF, it will fail.

Move the code that applies the magic offset into a helper, and call
that helper from all four ioctl entry points.

[hverkuil: drop unnecessary '= 0' in v4l2_m2m_querybuf() for ret]

Fixes: 7f98639 ("V4L/DVB: add memory-to-memory device helper framework for videobuf")
Fixes: 908a0d7 ("[media] v4l: mem2mem: port to videobuf2")
Signed-off-by: Chen-Yu Tsai <wenst@chromium.org>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>
[OP: backport to 5.4: adjusted return logic in v4l2_m2m_qbuf() to match the
logic in the original commit: call v4l2_m2m_adjust_mem_offset() only if !ret
and before the v4l2_m2m_try_schedule() call]
Signed-off-by: Ovidiu Panait <ovidiu.panait@windriver.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

Author: wens

drivers/media/v4l2-core/v4l2-mem2mem.c

@@ -460,28 +460,38 @@ int v4l2_m2m_reqbufs(struct file *file, struct v4l2_m2m_ctx *m2m_ctx,
 }
 EXPORT_SYMBOL_GPL(v4l2_m2m_reqbufs);
 
-int v4l2_m2m_querybuf(struct file *file, struct v4l2_m2m_ctx *m2m_ctx,
-		      struct v4l2_buffer *buf)
+static void v4l2_m2m_adjust_mem_offset(struct vb2_queue *vq,
+				       struct v4l2_buffer *buf)
 {
-	struct vb2_queue *vq;
-	int ret = 0;
-	unsigned int i;
-
-	vq = v4l2_m2m_get_vq(m2m_ctx, buf->type);
-	ret = vb2_querybuf(vq, buf);
-
 	/* Adjust MMAP memory offsets for the CAPTURE queue */
 	if (buf->memory == V4L2_MEMORY_MMAP && !V4L2_TYPE_IS_OUTPUT(vq->type)) {
 		if (V4L2_TYPE_IS_MULTIPLANAR(vq->type)) {
+			unsigned int i;
+
 			for (i = 0; i < buf->length; ++i)
 				buf->m.planes[i].m.mem_offset
 					+= DST_QUEUE_OFF_BASE;
 		} else {
 			buf->m.offset += DST_QUEUE_OFF_BASE;
 		}
 	}
+}
 
-	return ret;
+int v4l2_m2m_querybuf(struct file *file, struct v4l2_m2m_ctx *m2m_ctx,
+		      struct v4l2_buffer *buf)
+{
+	struct vb2_queue *vq;
+	int ret;
+
+	vq = v4l2_m2m_get_vq(m2m_ctx, buf->type);
+	ret = vb2_querybuf(vq, buf);
+	if (ret)
+		return ret;
+
+	/* Adjust MMAP memory offsets for the CAPTURE queue */
+	v4l2_m2m_adjust_mem_offset(vq, buf);
+
+	return 0;
 }
 EXPORT_SYMBOL_GPL(v4l2_m2m_querybuf);
 
@@ -500,20 +510,34 @@ int v4l2_m2m_qbuf(struct file *file, struct v4l2_m2m_ctx *m2m_ctx,
 		return -EPERM;
 	}
 	ret = vb2_qbuf(vq, vdev->v4l2_dev->mdev, buf);
-	if (!ret && !(buf->flags & V4L2_BUF_FLAG_IN_REQUEST))
+	if (ret)
+		return ret;
+
+	/* Adjust MMAP memory offsets for the CAPTURE queue */
+	v4l2_m2m_adjust_mem_offset(vq, buf);
+
+	if (!(buf->flags & V4L2_BUF_FLAG_IN_REQUEST))
 		v4l2_m2m_try_schedule(m2m_ctx);
 
-	return ret;
+	return 0;
 }
 EXPORT_SYMBOL_GPL(v4l2_m2m_qbuf);
 
 int v4l2_m2m_dqbuf(struct file *file, struct v4l2_m2m_ctx *m2m_ctx,
 		   struct v4l2_buffer *buf)
 {
 	struct vb2_queue *vq;
+	int ret;
 
 	vq = v4l2_m2m_get_vq(m2m_ctx, buf->type);
-	return vb2_dqbuf(vq, buf, file->f_flags & O_NONBLOCK);
+	ret = vb2_dqbuf(vq, buf, file->f_flags & O_NONBLOCK);
+	if (ret)
+		return ret;
+
+	/* Adjust MMAP memory offsets for the CAPTURE queue */
+	v4l2_m2m_adjust_mem_offset(vq, buf);
+
+	return 0;
 }
 EXPORT_SYMBOL_GPL(v4l2_m2m_dqbuf);
 
@@ -522,9 +546,17 @@ int v4l2_m2m_prepare_buf(struct file *file, struct v4l2_m2m_ctx *m2m_ctx,
 {
 	struct video_device *vdev = video_devdata(file);
 	struct vb2_queue *vq;
+	int ret;
 
 	vq = v4l2_m2m_get_vq(m2m_ctx, buf->type);
-	return vb2_prepare_buf(vq, vdev->v4l2_dev->mdev, buf);
+	ret = vb2_prepare_buf(vq, vdev->v4l2_dev->mdev, buf);
+	if (ret)
+		return ret;
+
+	/* Adjust MMAP memory offsets for the CAPTURE queue */
+	v4l2_m2m_adjust_mem_offset(vq, buf);
+
+	return 0;
 }
 EXPORT_SYMBOL_GPL(v4l2_m2m_prepare_buf);