On 3/31/22 21:27, Dmitry Osipenko wrote:
> On 3/30/22 23:47, Rob Clark wrote:
>> From: Rob Clark <robdclark@xxxxxxxxxxxx>
>>
>> Combines duplicate vma lookup in the get_and_pin path.
>>
>> Signed-off-by: Rob Clark <robdclark@xxxxxxxxxxxx>
>> ---
>> drivers/gpu/drm/msm/msm_gem.c | 50 ++++++++++++++++++-----------------
>> 1 file changed, 26 insertions(+), 24 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/msm/msm_gem.c b/drivers/gpu/drm/msm/msm_gem.c
>> index deafae6feaa8..218744a490a4 100644
>> --- a/drivers/gpu/drm/msm/msm_gem.c
>> +++ b/drivers/gpu/drm/msm/msm_gem.c
>> @@ -376,39 +376,40 @@ put_iova_vmas(struct drm_gem_object *obj)
>> }
>> }
>>
>> -static int get_iova_locked(struct drm_gem_object *obj,
>> - struct msm_gem_address_space *aspace, uint64_t *iova,
>> +static struct msm_gem_vma *get_vma_locked(struct drm_gem_object *obj,
>> + struct msm_gem_address_space *aspace,
>> u64 range_start, u64 range_end)
>> {
>> struct msm_gem_vma *vma;
>> - int ret = 0;
>>
>> GEM_WARN_ON(!msm_gem_is_locked(obj));
>>
>> vma = lookup_vma(obj, aspace);
>>
>> if (!vma) {
>> + int ret;
>> +
>> vma = add_vma(obj, aspace);
>> if (IS_ERR(vma))
>> - return PTR_ERR(vma);
>> + return vma;
>>
>> ret = msm_gem_init_vma(aspace, vma, obj->size,
>> range_start, range_end);
>> if (ret) {
> You're allocation range_start -> range_end
*allocating
>
>> del_vma(vma);
>> - return ret;
>> + return ERR_PTR(ret);
>> }
>> + } else {
>> + GEM_WARN_ON(vma->iova < range_start);
>> + GEM_WARN_ON((vma->iova + obj->size) > range_end);
>
> and then comparing range_start -> range_start + obj->size, hence you're
> assuming that range_end always equals to obj->size during the allocation.
>
> I'm not sure what is the idea here.. this looks inconsistent. I think
> you wanted to write:
>
> GEM_WARN_ON(vma->iova < range_start);
> GEM_WARN_ON(vma->iova + (vma->node.size << PAGE_SHIFT) > range_end);
>
> But is it really useful to check whether the new range is inside of the
> old range? Shouldn't it be always a error to change the IOVA range
> without reallocating vma?
>
> I'd expect to see:
>
> GEM_WARN_ON(vma->iova != range_start);
> GEM_WARN_ON(vma->iova + (vma->node.size << PAGE_SHIFT) != range_end);
>
> and then error out if range mismatches.
