iommu/vt-d: Change return type of dmar_insert_one_dev_info()

The dmar_insert_one_dev_info() returns the pass-in domain on success and
NULL on failure. This doesn't make much sense. Change it to an integer.
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20220416120423.879552-1-baolu.lu@linux.intel.com
Link: https://lore.kernel.org/r/20220510023407.2759143-3-baolu.lu@linux.intel.comSigned-off-by: Joerg Roedel <jroedel@suse.de>

drivers/iommu/intel/iommu.c

@@ -2452,10 +2452,9 @@ static bool dev_is_real_dma_subdevice(struct device *dev)
 	       pci_real_dma_dev(to_pci_dev(dev)) != to_pci_dev(dev);
 }
 
-static struct dmar_domain *dmar_insert_one_dev_info(struct intel_iommu *iommu,
-						    int bus, int devfn,
-						    struct device *dev,
-						    struct dmar_domain *domain)
+static int dmar_insert_one_dev_info(struct intel_iommu *iommu, int bus,
+				    int devfn, struct device *dev,
+				    struct dmar_domain *domain)
 {
 	struct device_domain_info *info = dev_iommu_priv_get(dev);
 	unsigned long flags;
@@ -2468,7 +2467,7 @@ static struct dmar_domain *dmar_insert_one_dev_info(struct intel_iommu *iommu,
 	spin_unlock(&iommu->lock);
 	if (ret) {
 		spin_unlock_irqrestore(&device_domain_lock, flags);
-		return NULL;
+		return ret;
 	}
 	list_add(&info->link, &domain->devices);
 	spin_unlock_irqrestore(&device_domain_lock, flags);
@@ -2479,7 +2478,7 @@ static struct dmar_domain *dmar_insert_one_dev_info(struct intel_iommu *iommu,
 		if (ret) {
 			dev_err(dev, "PASID table allocation failed\n");
 			dmar_remove_one_dev_info(dev);
-			return NULL;
+			return ret;
 		}
 
 		/* Setup the PASID entry for requests without PASID: */
@@ -2497,17 +2496,18 @@ static struct dmar_domain *dmar_insert_one_dev_info(struct intel_iommu *iommu,
 		if (ret) {
 			dev_err(dev, "Setup RID2PASID failed\n");
 			dmar_remove_one_dev_info(dev);
-			return NULL;
+			return ret;
 		}
 	}
 
-	if (domain_context_mapping(domain, dev)) {
+	ret = domain_context_mapping(domain, dev);
+	if (ret) {
 		dev_err(dev, "Domain context map failed\n");
 		dmar_remove_one_dev_info(dev);
-		return NULL;
+		return ret;
 	}
 
-	return domain;
+	return 0;
 }
 
 static int iommu_domain_identity_map(struct dmar_domain *domain,
@@ -2585,7 +2585,6 @@ static int __init si_domain_init(int hw)
 
 static int domain_add_dev_info(struct dmar_domain *domain, struct device *dev)
 {
-	struct dmar_domain *ndomain;
 	struct intel_iommu *iommu;
 	u8 bus, devfn;
 
@@ -2593,11 +2592,7 @@ static int domain_add_dev_info(struct dmar_domain *domain, struct device *dev)
 	if (!iommu)
 		return -ENODEV;
 
-	ndomain = dmar_insert_one_dev_info(iommu, bus, devfn, dev, domain);
-	if (ndomain != domain)
-		return -EBUSY;
-
-	return 0;
+	return dmar_insert_one_dev_info(iommu, bus, devfn, dev, domain);
 }
 
 static bool device_has_rmrr(struct device *dev)