iommufd: Add iommufd_lock_obj() around the auto-domains hwpts

A later patch will require this locking - currently under the ioas mutex
the hwpt can not have a 0 reference and be on the list.

Link: https://lore.kernel.org/r/2-v3-ae9c2975a131+2e1e8-iommufd_hwpt_jgg@nvidia.com
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

diff --git a/drivers/iommu/iommufd/device.c b/drivers/iommu/iommufd/device.c
index dcfaf65..0a80ff7 100644 (file)
--- a/drivers/iommu/iommufd/device.c
+++ b/drivers/iommu/iommufd/device.c
@@ -282,7 +282,10 @@ static int iommufd_device_auto_get_domain(struct iommufd_device *idev,
                if (!hwpt->auto_domain)
                        continue;
 
+               if (!iommufd_lock_obj(&hwpt->obj))
+                       continue;
                rc = iommufd_device_do_attach(idev, hwpt);
+               iommufd_put_object(&hwpt->obj);
 
                /*
                 * -EINVAL means the domain is incompatible with the device.