2016-06-23 Chris Wilson <chris at chris-wilson.co.uk>:
> On Thu, Jun 23, 2016 at 12:29:50PM -0300, Gustavo Padovan wrote:
> > -static void sync_file_add_pt(struct sync_file *sync_file, int *i,
> > +static int sync_file_set_fence(struct sync_file *sync_file,
> > + struct fence **fences)
> > +{
> > + struct fence_array *array;
> > +
> > + if (sync_file->num_fences == 1) {
> > + sync_file->fence = fences[0];
>
> Straightforward pointer assignment.
>
> > + } else {
> > + array = fence_array_create(sync_file->num_fences, fences,
> > + fence_context_alloc(1), 1, false);
> > + if (!array)
> > + return -ENOMEM;
> > +
> > + sync_file->fence = &array->base;
>
> New reference.
>
> Imbalance will promptly go bang after we release the single fence[0].
>
> Would fence_array_create(1, fence) returning fence_get(fence) be too
> much of a hack?
>
> I would suggest dropping the exported fence_get_fences() and use a local
> instead that could avoid the copy, e.g.
>
> static struct fence *get_fences(struct fence **fence,
> unsigned int *num_fences)
> {
> if (fence_is_array(*fence)) {
> struct fence_array *array = to_fence_array(*fence);
> *num_fences = array->num_fences;
> return array->fences;
> } else {
> *num_fences = 1;
> return fence;
> }
> }
>
> sync_file_merge() {
> int num_fences, num_a_fences, num_b_fences;
> struct fence **fences, **a_fences, **b_fences;
>
> a_fences = get_fences(&a, &num_a_fences);
> b_fences = get_fences(&b, &num_b_fences);
>
> num_fences = num_a_fences + num_b_fences;
Yes. That is much cleaner solution. I did this initially but then tried
to come up with .get_fences(), but that was the wrong road.
>
> > static void sync_file_free(struct kref *kref)
> > {
> > struct sync_file *sync_file = container_of(kref, struct sync_file,
> > kref);
> > - int i;
> > -
> > - for (i = 0; i < sync_file->num_fences; ++i) {
> > - fence_remove_callback(sync_file->cbs[i].fence,
> > - &sync_file->cbs[i].cb);
> > - fence_put(sync_file->cbs[i].fence);
> > - }
> >
> > + fence_remove_callback(sync_file->fence, &sync_file->cb);
> > + fence_teardown(sync_file->fence);
>
> Hmm. Could we detect the removal of the last callback and propagate that
> to the fence_array? (Rather then introduce a manual call to
> fence_teardown.)
Maybe. I'll look into ways to identify that. What I did during the
development of this patch was to have a fence_array_destroy(), but then
I moved to .teardown() in the hope to abstract the diff between fences
and fence_arrays.
Gustavo
