[Mesa-dev] [PATCH] clover: Increment an object's reference count in ret_object()

[Francisco Jerez]

Tom Stellard <tstellar at gmail.com> writes:

> We need to increment the reference count for objects, like cl_event,
> that the user is responsible for destroying when they are returned from
> the API.  Otherwise, the object will be destroyed when clover is done with
> it, even though the user will still have a reference to it.  For example:
>
> 1. clEnqueueNDRangeKernel(queue, ... , &event)
>   - create an event object
>   - refcount = 1
>
> 2. clFlush(queue)
>   - event object is removed from the queue and its reference count is
>     decremented.
>   - refcount = 0, event is deleted
>
> 3. clGetEventInfo(event, ...)
>   - segfault

I don't think this could cause the problem you've seen...  After step 1
the event object ends up queued in queue->queued_events, a ref_ptr<>
list that holds additional references to each object it contains, so,
after step 1 refcount is supposed to be 2 already...  You're probably
hitting something more subtle, try the attached patch.

PS: Can you CC me when you send clover-related patches to the mailing
    list?  I'm likely to miss them otherwise.

> ---
>  src/gallium/state_trackers/clover/api/util.hpp |    4 +++-
>  1 files changed, 3 insertions(+), 1 deletions(-)
>
> diff --git a/src/gallium/state_trackers/clover/api/util.hpp b/src/gallium/state_trackers/clover/api/util.hpp
> index 2f9ec1f..5cfc528 100644
> --- a/src/gallium/state_trackers/clover/api/util.hpp
> +++ b/src/gallium/state_trackers/clover/api/util.hpp
> @@ -156,8 +156,10 @@ namespace clover {
>     template<typename T, typename S>
>     void
>     ret_object(T p, S v) {
> -      if (p)
> +      if (p) {
>           *p = v;
> +         v->retain();
> +      }
>        else
>           v->release();
>     }

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