Re: [RFC v5 07/11] [media] vb2: add in-fence support to QBUF

[Mauro Carvalho Chehab]

Em Fri, 17 Nov 2017 15:49:23 +0900
Alexandre Courbot <acourbot@xxxxxxxxxxxx> escreveu:

> > @@ -178,6 +179,12 @@ static int vb2_queue_or_prepare_buf(struct 
> > vb2_queue *q, struct v4l2_buffer *b,
> >  		return -EINVAL;
> >  	}
> >  
> > +	if ((b->fence_fd != 0 && b->fence_fd != -1) &&  
> 
> Why do we need to consider both values invalid? Can 0 ever be a valid fence 
> fd?

Programs that don't use fences will initialize reserved2/fence_fd field
at the uAPI call to zero.

So, I guess using fd=0 here could be a problem. Anyway, I would, instead,
do:

	if ((b->fence_fd < 1) &&
		...

as other negative values are likely invalid as well.

-- 
Thanks,
Mauro