Re: [Qemu-devel] [PATCH v12 11/22] vfio iommu: Add blocking notifier to notify DMA_UNMAP

[Kirti Wankhede]

>> @@ -854,15 +857,29 @@ static int vfio_dma_do_unmap(struct vfio_iommu *iommu,
>>              if (dma->task->mm != current->mm)
>>                      break;
>>              unmapped += dma->size;
>> +
>> +            mutex_unlock(&iommu->lock);
>> +            if (iommu->external_domain && !RB_EMPTY_ROOT(&dma->pfn_list)) {
>> +                    struct vfio_iommu_type1_dma_unmap nb_unmap;
>> +
>> +                    nb_unmap.iova = dma->iova;
>> +                    nb_unmap.size = dma->size;
>> +                    blocking_notifier_call_chain(&iommu->notifier,
>> +                                                VFIO_IOMMU_NOTIFY_DMA_UNMAP,
>> +                                                &nb_unmap);
>> +
>> +                    if (WARN_ON(!RB_EMPTY_ROOT(&dma->pfn_list)))
>> +                            goto unmap_exit;
>> +            }
>> +            mutex_lock(&iommu->lock);
> 
> Why are the mutexes pushed out so far, we are referencing way too much
> stuff outside of the mutex here.  The notifier head has its own
> semaphore, so we should be able to squeeze the mutex opening to just
> around the notifier call, in which case we only worry about the iommu
> itself going way.
> 

Right. Updating.

Thanks,
Kirti