Re: [PATCH v14 05/56] media: videobuf2: Access vb2_queue bufs array through helper functions

[Benjamin Gaignard]

Le 08/11/2023 à 09:50, Tomasz Figa a écrit :
> On Tue, Oct 31, 2023 at 05:30:13PM +0100, Benjamin Gaignard wrote:
> > This patch adds 2 helpers functions to add and remove vb2 buffers
> > from a queue. With these 2 and vb2_get_buffer(), bufs field of
> > struct vb2_queue becomes like a private member of the structure.
> >
> > After each call to vb2_get_buffer() we need to be sure that we get
> > a valid pointer in preparation for when buffers can be deleted.
> >
> > Signed-off-by: Benjamin Gaignard <benjamin.gaignard@xxxxxxxxxxxxx>
> > ---
> >   .../media/common/videobuf2/videobuf2-core.c   | 151 +++++++++++++-----
> >   .../media/common/videobuf2/videobuf2-v4l2.c   |  50 ++++--
> >   2 files changed, 149 insertions(+), 52 deletions(-)
> >
> > diff --git a/drivers/media/common/videobuf2/videobuf2-core.c b/drivers/media/common/videobuf2/videobuf2-core.c
> > index 968b7c0e7934..b406a30a9b35 100644
> > --- a/drivers/media/common/videobuf2/videobuf2-core.c
> > +++ b/drivers/media/common/videobuf2/videobuf2-core.c
> > @@ -408,6 +408,31 @@ static void init_buffer_cache_hints(struct vb2_queue *q, struct vb2_buffer *vb)
> >   		vb->skip_cache_sync_on_finish = 1;
> >   }
> >   
> > +/**
> > + * vb2_queue_add_buffer() - add a buffer to a queue
> > + * @q:	pointer to &struct vb2_queue with videobuf2 queue.
> > + * @vb:	pointer to &struct vb2_buffer to be added to the queue.
> > + * @index: index where add vb2_buffer in the queue
> > + */
> > +static void vb2_queue_add_buffer(struct vb2_queue *q, struct vb2_buffer *vb, unsigned int index)
> > +{
> > +	WARN_ON(index >= VB2_MAX_FRAME || q->bufs[index]);
> nit: Would it make sense to also ensure that vb->vb2_queue is NULL?

Since vb->vb2_queue and q->bufs[index] are always set and clear in the same
functions I don't think it is useful to test the both here.

> > +
> > +	q->bufs[index] = vb;
> > +	vb->index = index;
> > +	vb->vb2_queue = q;
> > +}
> [snip]
> > diff --git a/drivers/media/common/videobuf2/videobuf2-v4l2.c b/drivers/media/common/videobuf2/videobuf2-v4l2.c
> > index d19d82a75ac6..2ffb097bf00a 100644
> > --- a/drivers/media/common/videobuf2/videobuf2-v4l2.c
> > +++ b/drivers/media/common/videobuf2/videobuf2-v4l2.c
> > @@ -377,6 +377,12 @@ static int vb2_queue_or_prepare_buf(struct vb2_queue *q, struct media_device *md
> >   		return -EINVAL;
> >   	}
> >   
> > +	vb = vb2_get_buffer(q, b->index);
> > +	if (!vb) {
> > +		dprintk(q, 1, "%s: buffer %u is NULL\n", opname,  b->index);
> > +		return -EINVAL;
> > +	}
> > +
> Is this a leftover from earlier revisions? I think it shouldn't be
> needed anymore after the previous patch which changed the function to
> get vb as an argument.

You are right I will fix it.

> Best regards,
> Tomasz
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