On Mon, Aug 11, 2025 at 03:59:10PM -0700, Nicolin Chen wrote:
> Introduce a new iommu_get_domain_for_dev_locked() helper to be used by
> those drivers in a context that is already under the protection of the
> group->mutex, e.g. those attach_dev callback functions. And roll out the
> new helper to all the existing IOMMU drivers.
I still don't much care for this, I think it would be better to
approach this problem by passing the old domain to the driver callback:
> @@ -390,7 +390,7 @@ static int qcom_iommu_attach_dev(struct iommu_domain *domain, struct device *dev
> static int qcom_iommu_identity_attach(struct iommu_domain *identity_domain,
> struct device *dev)
> {
> - struct iommu_domain *domain = iommu_get_domain_for_dev(dev);
> + struct iommu_domain *domain = iommu_get_domain_for_dev_locked(dev);
Because this is a very common pattern in drivers.
Once that is done we can see what calls to iommu_get_domain_for_dev()
are even left, arguably we should be trying to eliminate this badly
locked thing...
Jason
