[Mesa-dev] [PATCH v3 1/1] clover: use pipe_resource references

[Vedran Miletić]

On 03/17/2017 05:20 AM, Jan Vesely wrote:
> On Thu, 2017-03-16 at 18:07 -0700, Francisco Jerez wrote:
>> Jan Vesely <jan.vesely at rutgers.edu> writes:
>>
>>> On Thu, 2017-03-16 at 17:22 -0700, Francisco Jerez wrote:
>>>> Jan Vesely <jan.vesely at rutgers.edu> writes:
>>>>
>>>>> On Thu, 2017-03-16 at 15:24 -0700, Francisco Jerez wrote:
>>>>>> Jan Vesely <jan.vesely at rutgers.edu> writes:
>>>>>>
>>>>>>> v2: buffers are created with one reference.
>>>>>>> v3: add pipe_resource reference to mapping object
>>>>>>>
>>>>>>
>>>>>> Mapping objects are supposed to be short-lived, they're logically part
>>>>>> of the parent resource object so they shouldn't ever out-live it.  What
>>>>>> is this useful for?
>>>>>
>>>>> currently they can outlive the underlying pipe_resource. pipe_resource
>>>>> is destroyed in root_resource destructor, while the list of mappings is
>>>>> destroyed after resource destructor.
>>>>
>>>> Right.  I guess the problem is that the pipe_transfer object associated
>>>> to the clover::mapping object holds a pointer to the backing
>>>> pipe_resource object but it fails to increment its reference count?  I
>>>> guess that's the reason why v2 didn't help?
>>>
>>> yes, though the pointer is hidden somewhere. I thought pxfer->resource
>>> might be it, but it's not, and digging deeper into the structure didn't
>>> sound like a good idea to me.
>>>
>>
>> What is pxfer->resource about in that case?
> 
> that's a good question, so I did a bit of digging. for EG global
> buffers are shadowed in global buffer memory pool, so mapping uses
> memory pool's pipe_resource. I'm still not 100% sure where exactly
> unmapping the global pool accesses the original buffer's pipe_resource,
> but I don't think it matters that much. It's not required for pxfer-
>> resource to be equal to resource->pipe. we need to guarantee that
> resource->pipe outlives all mappings.
> either explicitly, or by grabbing reference.
> 
> Jan
> 

Jan's v3 solves the problem, as does my version.

Francisco, do you have a particular preference how should we proceed?

Regards,
Vedran

-- 
Vedran Miletić
vedran.miletic.net