On Mon, Jun 06, 2022 at 09:34:36PM -0300, Jason Gunthorpe wrote:
> + if (!list_empty(&iommu->device_list)) {
> + mutex_lock(&iommu->device_list_lock);
> + mutex_unlock(&iommu->lock);
> +
> + list_for_each_entry(device,
> + &iommu->device_list,
> + iommu_entry)
> + device->ops->dma_unmap(
> + device, dma->iova, dma->size);
> +
> + mutex_unlock(&iommu->device_list_lock);
> + mutex_lock(&iommu->lock);
> + }
I wonder if factoring this into a little helper instead of the
very deep indentation might be a bit better for readability.
> +static void vfio_iommu_type1_register_device(void *iommu_data,
> + struct vfio_device *vdev)
> {
> struct vfio_iommu *iommu = iommu_data;
>
> + if (!vdev->ops->dma_unmap)
> + return;
>
> + mutex_lock(&iommu->lock);
> + mutex_lock(&iommu->device_list_lock);
> + list_add(&vdev->iommu_entry, &iommu->device_list);
> + mutex_unlock(&iommu->device_list_lock);
> + mutex_unlock(&iommu->lock);
Why do we need both iommu->lock and the device_list_lock everywhere?
Maybe explain the locking scheme somewhere so that people don't have
to guess, because it seems to me that just using iommu->lock would
be enough right now.
