Re: [PATCH v2 5/8] iommu: Switch __iommu_domain_alloc() to device ops

Jacob Pan
2023-01-26T23:19:15Z

Hi Robin,

On Thu, 26 Jan 2023 18:26:20 +0000, Robin Murphy <robin.murphy@arm.com>
wrote:

>
> +static int __iommu_domain_alloc_dev(struct device *dev, void *data)
> +{
> + struct device **alloc_dev = data;
> +
> + if (!dev_iommu_ops_valid(dev))
> + return 0;
> +
> + WARN_ONCE(*alloc_dev && dev_iommu_ops(dev) !=
> dev_iommu_ops(*alloc_dev),
> + "Multiple IOMMU drivers present, which the public IOMMU
> API can't fully support yet. You may still need to disable one or more to
> get the expected result here, sorry!\n"); +
> + *alloc_dev = dev;
> + return 0;
> +}
> +
> struct iommu_domain *iommu_domain_alloc(struct bus_type *bus)
> {
> - return __iommu_domain_alloc(bus, IOMMU_DOMAIN_UNMANAGED);
> + struct device *dev = NULL;
> +
> + /* We always check the whole bus, so the return value isn't
> useful */
> + bus_for_each_dev(bus, NULL, &dev, __iommu_domain_alloc_dev);
> + if (!dev)
> + return NULL;
Since __iommu_domain_alloc_dev() will always return 0, bus_for_each_dev()
will never breakout until the whole dev list is iterated over. If so, would
dev only record the last one? i.e. prior results get overwritten. Maybe a
misunderstood the logic.

> + return __iommu_domain_alloc(dev, IOMMU_DOMAIN_UNMANAGED);
> }
> EXPORT_SYMBOL_GPL(iommu_domain_alloc);

Thanks,

Jacob