Re: [PATCH v3 12/15] iommufd: Add kAPI toward external drivers for physical devices

[Baolu Lu <baolu.lu@linux.intel.com>]

On 2022/10/26 2:12, Jason Gunthorpe wrote:
> +/*
> + * When automatically managing the domains we search for a compatible domain in
> + * the iopt and if one is found use it, otherwise create a new domain.
> + * Automatic domain selection will never pick a manually created domain.
> + */
> +static int iommufd_device_auto_get_domain(struct iommufd_device *idev,
> +					  struct iommufd_ioas *ioas,
> +					  unsigned int flags)
> +{
> +	struct iommufd_hw_pagetable *hwpt;
> +	int rc;
> +
> +	/*
> +	 * There is no differentiation when domains are allocated, so any domain
> +	 * that is willing to attach to the device is interchangeable with any
> +	 * other.
> +	 */
> +	mutex_lock(&ioas->mutex);
> +	list_for_each_entry(hwpt, &ioas->hwpt_list, hwpt_item) {
> +		if (!hwpt->auto_domain ||
> +		    !refcount_inc_not_zero(&hwpt->obj.users))
> +			continue;
> +
> +		rc = iommufd_device_do_attach(idev, hwpt, flags);
> +		refcount_dec(&hwpt->obj.users);
> +		if (rc) {
> +			/*
> +			 * FIXME: Requires the series to return EINVAL for
> +			 * incompatible domain attaches.
> +			 */
> +			if (rc == -EINVAL)
> +				continue;
> +			goto out_unlock;
> +		}
> +		goto out_unlock;

Can the above code be simplified as:

		if (rc == -EINVAL)
			continue;
		goto out_unlock;
?

> +	}
> +
> +	hwpt = iommufd_hw_pagetable_alloc(idev->ictx, ioas, idev->dev);
> +	if (IS_ERR(hwpt)) {
> +		rc = PTR_ERR(hwpt);
> +		goto out_unlock;
> +	}
> +	hwpt->auto_domain = true;
> +
> +	rc = iommufd_device_do_attach(idev, hwpt, flags);
> +	if (rc)
> +		goto out_abort;
> +	list_add_tail(&hwpt->hwpt_item, &ioas->hwpt_list);
> +
> +	mutex_unlock(&ioas->mutex);
> +	iommufd_object_finalize(idev->ictx, &hwpt->obj);
> +	return 0;
> +
> +out_abort:
> +	iommufd_object_abort_and_destroy(idev->ictx, &hwpt->obj);
> +out_unlock:
> +	mutex_unlock(&ioas->mutex);
> +	return rc;
> +}

Best regards,
baolu