Re: [PATCH] drm/i915: Move ioremap_wc tracking onto VMA

[Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>]

On 15/04/16 11:38, Chris Wilson wrote:
> On Fri, Apr 15, 2016 at 11:19:30AM +0100, Tvrtko Ursulin wrote:
>> On 15/04/16 11:00, Chris Wilson wrote:
>>> On Fri, Apr 15, 2016 at 10:40:42AM +0100, Tvrtko Ursulin wrote:
>>>>
>>>> On 13/04/16 16:12, Chris Wilson wrote:
>>>>> On Wed, Apr 13, 2016 at 03:47:58PM +0100, Chris Wilson wrote:
>>>>>> +	/* We also want to clear any cached iomaps as they wrap vmap */
>>>>>> +	list_for_each_entry_safe(vma, next,
>>>>>> +				 &dev_priv->ggtt.base.inactive_list, vm_link)
>>>>>> +		if (vma->iomap && i915_vma_unbind(vma) == 0)
>>>>>> +			freed_pages += vma->node.size >> PAGE_SHIFT;
>>>>>
>>>>> Use after free. I need to store the page count in a local before calling
>>>>> unbind.
>>>>
>>>> Waiting for respin. :)
>>>>
>>>> Also, shouldn't the patch which adds the size argument to
>>>> io_mapping_map_wc be in this series?
>>>
>>> It was, this was just an update to patch 2. The delta here is just
>>> unsigned long count = vma->node.size >> PAGE_SHIFT;
>>> if (vma->iomap && i915_vma_unbind(vma) == 0)
>>> 	freed_pages += count;
>>
>> My bad, I got lost in the threads.. :(
>>
>> Could I ask for those two BUG_ONs to be replaced with GEM_BUG_ONs
>> now that is in?
>>
>> Maybe also add a quick return at the top, as a micro-opt:
>>
>> 	if (vma->iomap)
>> 		reutrn vma->iomap;
>>
>> Followed by WARNs, GEM_BUG_ONs and rest?
>
> Like so?
>
> void *i915_vma_iomap(struct i915_vma *vma)
> {
>          struct i915_ggtt *ggtt;
>          void *ptr;
>
>          if (vma->iomap)
>                  return vma->iomap;
>
>          if (WARN_ON(!vma->obj->map_and_fenceable))
>                  return ERR_PTR(-ENODEV);
>
>          GEM_BUG_ON(!vma->is_ggtt);
>          GEM_BUG_ON((vma->bound & GLOBAL_BIND) == 0);
>
>          ggtt = container_of(vma->vm, struct i915_ggtt, base);
>          ptr = io_mapping_map_wc(ggtt->mappable vma->node.start, vma->node.size);
>          if (ptr == NULL)
>                  return ERR_PTR(-ENOMEM);
>
>          vma->iomap = ptr;
>          return ptr;
> }

Yes, that's what I had in mind. You can put my r-b in the repost.

Regards,

Tvrtko
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