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

[Francisco Jerez]

Tom Stellard <thomas.stellard at amd.com> writes:

> On Thu, Jun 28, 2012 at 01:09:20AM +0200, Francisco Jerez wrote:
>> 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.
>>
>
> I missed that part about ref_ptr.  I'll have to look at that again.
> However that sequence is causing a segfault in clGetEventInfo in all
> of the AMD OpenCL SDK examples (or at least all of them that make it
> that far), and it is because the event is being deleted too early.
>
Yes, probably because the user-defined copy constructor of
ref_ptr<hard_event> is not being used by the event queue because it's
defined as a template, try the patch I attached.

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