On Thu, Feb 13, 2014 at 6:40 PM, Hans Verkuil <hverkuil@xxxxxxxxx> wrote:
> From: Hans Verkuil <hans.verkuil@xxxxxxxxx>
>
> Ensure that these ops are properly balanced.
>
> There two scenarios:
s/There two/There are two/
>
> 1) for MMAP buf_init is called when the buffers are created and buf_cleanup
> must be called when the queue is finally freed. This scenario was always
> working.
>
> 2) for USERPTR and DMABUF it is more complicated. When a buffer is queued
> the code checks if all planes of this buffer have been acquired before.
> If that's the case, then only buf_prepare has to be called. Otherwise
> buf_clean needs to be called if the buffer was acquired before, then,
s/buf_clean/buf_cleanup/
> once all changed planes have been (re)acquired, buf_init has to be
> called again followed by buf_prepare. Should buf_prepare fail, then
s/again//
I know what you mean, but there is only one call to buf_init in this
particular sequence.
> buf_cleanup must be called again because all planes will be released
s/again because all planes will be released/on the newly acquired
planes to release them/
> in case of an error.
>
> Finally, in __vb2_queue_free we have to check if the buffer was actually
> acquired before calling buf_cleanup. While that it always true for MMAP
> mode, it is not necessarily true for the other modes. E.g. if you just
> call REQBUFS and close the filehandle, then buffers were ever queued and
s/ever/never/
s/filehandle/file handle/
> so no buf_init was ever called.
>
> Signed-off-by: Hans Verkuil <hans.verkuil@xxxxxxxxx>
> ---
> drivers/media/v4l2-core/videobuf2-core.c | 100 +++++++++++++++++++++----------
> 1 file changed, 67 insertions(+), 33 deletions(-)
>
> diff --git a/drivers/media/v4l2-core/videobuf2-core.c b/drivers/media/v4l2-core/videobuf2-core.c
> index 3756378..7766bf5 100644
> --- a/drivers/media/v4l2-core/videobuf2-core.c
> +++ b/drivers/media/v4l2-core/videobuf2-core.c
> @@ -373,8 +373,10 @@ static int __vb2_queue_free(struct vb2_queue *q, unsigned int buffers)
> /* Call driver-provided cleanup function for each buffer, if provided */
> for (buffer = q->num_buffers - buffers; buffer < q->num_buffers;
> ++buffer) {
> - if (q->bufs[buffer])
> - call_vb_qop(q->bufs[buffer], buf_cleanup, q->bufs[buffer]);
> + struct vb2_buffer *vb = q->bufs[buffer];
> +
> + if (vb && vb->planes[0].mem_priv)
> + call_vb_qop(vb, buf_cleanup, vb);
> }
>
> /* Release video buffer memory */
> @@ -1161,6 +1163,7 @@ static int __qbuf_userptr(struct vb2_buffer *vb, const struct v4l2_buffer *b)
> unsigned int plane;
> int ret;
> int write = !V4L2_TYPE_IS_OUTPUT(q->type);
> + bool reacquired = vb->planes[0].mem_priv == NULL;
This requires a comment I feel. In general, I'm not especially happy
with the fact that we are making mem_priv != NULL equivalent to
buf_init() called and succeeded. It is true right now, but it'll be
very hard to make the association without previously seeing this very
patch I feel.
I don't see a perfect way to do this, but I'm strongly leaning towards
having a bool inited in the vb2_buffer. Really.
>
> /* Copy relevant information provided by the userspace */
> __fill_vb2_buffer(vb, b, planes);
> @@ -1186,12 +1189,16 @@ static int __qbuf_userptr(struct vb2_buffer *vb, const struct v4l2_buffer *b)
> }
>
> /* Release previously acquired memory if present */
> - if (vb->planes[plane].mem_priv)
> + if (vb->planes[plane].mem_priv) {
> + if (!reacquired) {
> + reacquired = true;
> + call_vb_qop(vb, buf_cleanup, vb);
> + }
> call_memop(vb, put_userptr, vb->planes[plane].mem_priv);
> + }
>
> vb->planes[plane].mem_priv = NULL;
> - vb->v4l2_planes[plane].m.userptr = 0;
> - vb->v4l2_planes[plane].length = 0;
> + memset(&vb->v4l2_planes[plane], 0, sizeof(struct v4l2_plane));
>
> /* Acquire each plane's memory */
> mem_priv = call_memop(vb, get_userptr, q->alloc_ctx[plane],
> @@ -1208,23 +1215,34 @@ static int __qbuf_userptr(struct vb2_buffer *vb, const struct v4l2_buffer *b)
> }
>
> /*
> - * Call driver-specific initialization on the newly acquired buffer,
> - * if provided.
> - */
> - ret = call_vb_qop(vb, buf_init, vb);
> - if (ret) {
> - dprintk(1, "qbuf: buffer initialization failed\n");
> - fail_vb_qop(vb, buf_init);
> - goto err;
> - }
> -
> - /*
> * Now that everything is in order, copy relevant information
> * provided by userspace.
> */
> for (plane = 0; plane < vb->num_planes; ++plane)
> vb->v4l2_planes[plane] = planes[plane];
>
> + if (reacquired) {l
> + /*
> + * One or more planes changed, so we must call buf_init to do
> + * the driver-specific initialization on the newly acquired
> + * buffer, if provided.
> + */
> + ret = call_vb_qop(vb, buf_init, vb);
> + if (ret) {
> + dprintk(1, "qbuf: buffer initialization failed\n");
> + fail_vb_qop(vb, buf_init);
> + goto err;
> + }
> + }
> +
> + ret = call_vb_qop(vb, buf_prepare, vb);
> + if (ret) {
> + dprintk(1, "qbuf: buffer preparation failed\n");
> + fail_vb_qop(vb, buf_prepare);
> + call_vb_qop(vb, buf_cleanup, vb);
> + goto err;
> + }
> +
> return 0;
> err:
> /* In case of errors, release planes that were already acquired */
> @@ -1244,8 +1262,13 @@ err:
> */
> static int __qbuf_mmap(struct vb2_buffer *vb, const struct v4l2_buffer *b)
> {
> + int ret;
> +
> __fill_vb2_buffer(vb, b, vb->v4l2_planes);
> - return 0;
> + ret = call_vb_qop(vb, buf_prepare, vb);
> + if (ret)
> + fail_vb_qop(vb, buf_prepare);
> + return ret;
> }
>
> /**
> @@ -1259,6 +1282,7 @@ static int __qbuf_dmabuf(struct vb2_buffer *vb, const struct v4l2_buffer *b)
> unsigned int plane;
> int ret;
> int write = !V4L2_TYPE_IS_OUTPUT(q->type);
> + bool reacquired = vb->planes[0].mem_priv == NULL;
>
> /* Copy relevant information provided by the userspace */
> __fill_vb2_buffer(vb, b, planes);
> @@ -1294,6 +1318,11 @@ static int __qbuf_dmabuf(struct vb2_buffer *vb, const struct v4l2_buffer *b)
>
> dprintk(1, "qbuf: buffer for plane %d changed\n", plane);
>
> + if (!reacquired) {
> + reacquired = true;
> + call_vb_qop(vb, buf_cleanup, vb);
> + }
> +
> /* Release previously acquired memory if present */
> __vb2_plane_dmabuf_put(vb, &vb->planes[plane]);
> memset(&vb->v4l2_planes[plane], 0, sizeof(struct v4l2_plane));
> @@ -1329,23 +1358,33 @@ static int __qbuf_dmabuf(struct vb2_buffer *vb, const struct v4l2_buffer *b)
> }
>
> /*
> - * Call driver-specific initialization on the newly acquired buffer,
> - * if provided.
> - */
> - ret = call_vb_qop(vb, buf_init, vb);
> - if (ret) {
> - dprintk(1, "qbuf: buffer initialization failed\n");
> - fail_vb_qop(vb, buf_init);
> - goto err;
> - }
> -
> - /*
> * Now that everything is in order, copy relevant information
> * provided by userspace.
> */
> for (plane = 0; plane < vb->num_planes; ++plane)
> vb->v4l2_planes[plane] = planes[plane];
>
> + if (reacquired) {
This sequence until 'return 0" is an exact same code as in
__qbuf_userptr. Could we extract this?
I'm thinking that we could do this:
- rename __qbuf_userptr and __qbuf_dmabuf to __acquire_userptr/dmabuf
and have them return whether reacquired
- extract the sequence above and call buf_prepare from __buf_prepare
for userptr and dmabuf after calling __acquire_*
- get rid of qbuf_dmabuf, instead just call buf_prepare from
__buf_prepare directly like for useptr and dmabuf
> + /*
> + * Call driver-specific initialization on the newly acquired buffer,
> + * if provided.
> + */
> + ret = call_vb_qop(vb, buf_init, vb);
> + if (ret) {
> + dprintk(1, "qbuf: buffer initialization failed\n");
> + fail_vb_qop(vb, buf_init);
> + goto err;
> + }
> + }
> +
> + ret = call_vb_qop(vb, buf_prepare, vb);
> + if (ret) {
> + dprintk(1, "qbuf: buffer preparation failed\n");
> + fail_vb_qop(vb, buf_prepare);
> + call_vb_qop(vb, buf_cleanup, vb);
Should we explicitly set mem_priv to NULL here? This is one the issues
I have with using mem_priv, it's hard to reason if it's ok to do
buf_cleanup and expect mem_priv to be NULL here always.
Could we please add that inited bool into vb2_buffer to make it simpler?
> + goto err;
> + }
> +
> return 0;
> err:
> /* In case of errors, release planes that were already acquired */
> @@ -1420,11 +1459,6 @@ static int __buf_prepare(struct vb2_buffer *vb, const struct v4l2_buffer *b)
> ret = -EINVAL;
> }
>
> - if (!ret) {
> - ret = call_vb_qop(vb, buf_prepare, vb);
> - if (ret)
> - fail_vb_qop(vb, buf_prepare);
> - }
> if (ret)
> dprintk(1, "qbuf: buffer preparation failed: %d\n", ret);
> vb->state = ret ? VB2_BUF_STATE_DEQUEUED : VB2_BUF_STATE_PREPARED;
> --
> 1.8.4.rc3
>
--
Best regards,
Pawel Osciak
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