iommu: Move the iommu driver sysfs setup into iommu_init/deinit_device()

It makes logical sense that once the driver is attached to the device the
sysfs links appear, even if we haven't fully created the group_device or
attached the device to a domain.

Fix the missing error handling on sysfs creation since
iommu_init_device() can trivially handle this.

Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/6-v3-328044aa278c+45e49-iommu_probe_jgg@nvidia.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>

drivers/iommu/iommu-sysfs.c

@@ -107,9 +107,6 @@ int iommu_device_link(struct iommu_device *iommu, struct device *link)
 {
 	int ret;
 
-	if (!iommu || IS_ERR(iommu))
-		return -ENODEV;
-
 	ret = sysfs_add_link_to_group(&iommu->dev->kobj, "devices",
 				      &link->kobj, dev_name(link));
 	if (ret)
@@ -126,9 +123,6 @@ EXPORT_SYMBOL_GPL(iommu_device_link);
 
 void iommu_device_unlink(struct iommu_device *iommu, struct device *link)
 {
-	if (!iommu || IS_ERR(iommu))
-		return;
-
 	sysfs_remove_link(&link->kobj, "iommu");
 	sysfs_remove_link_from_group(&iommu->dev->kobj, "devices", dev_name(link));
 }

drivers/iommu/iommu.c

@@ -356,12 +356,16 @@ static int iommu_init_device(struct device *dev, const struct iommu_ops *ops)
 		goto err_module_put;
 	}
 
+	ret = iommu_device_link(iommu_dev, dev);
+	if (ret)
+		goto err_release;
+
 	group = ops->device_group(dev);
 	if (WARN_ON_ONCE(group == NULL))
 		group = ERR_PTR(-EINVAL);
 	if (IS_ERR(group)) {
 		ret = PTR_ERR(group);
-		goto err_release;
+		goto err_unlink;
 	}
 	dev->iommu_group = group;
 
@@ -371,6 +375,8 @@ static int iommu_init_device(struct device *dev, const struct iommu_ops *ops)
 		dev->iommu->attach_deferred = ops->is_attach_deferred(dev);
 	return 0;
 
+err_unlink:
+	iommu_device_unlink(iommu_dev, dev);
 err_release:
 	if (ops->release_device)
 		ops->release_device(dev);
@@ -388,6 +394,8 @@ static void iommu_deinit_device(struct device *dev)
 
 	lockdep_assert_held(&group->mutex);
 
+	iommu_device_unlink(dev->iommu->iommu_dev, dev);
+
 	/*
 	 * release_device() must stop using any attached domain on the device.
 	 * If there are still other devices in the group they are not effected
@@ -462,7 +470,6 @@ static int __iommu_probe_device(struct device *dev, struct list_head *group_list
 	iommu_group_put(group);
 
 	mutex_unlock(&iommu_probe_device_lock);
-	iommu_device_link(dev->iommu->iommu_dev, dev);
 
 	return 0;
 
@@ -584,8 +591,6 @@ static void iommu_release_device(struct device *dev)
 	if (!dev->iommu || !group)
 		return;
 
-	iommu_device_unlink(dev->iommu->iommu_dev, dev);
-
 	__iommu_group_remove_device(dev);
 }