iommu/vt-d: fix PCI device reference leakage on error recovery path

Function dmar_parse_dev_scope() should release the PCI device reference
count gained in function dmar_parse_one_dev_scope() on error recovery,
otherwise it will cause PCI device object leakage.

This patch also introduces dmar_free_dev_scope(), which will be used
to support DMAR device hotplug.

Reviewed-by: Yijing Wang <wangyijing@huawei.com>
Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com>
Signed-off-by: Joerg Roedel <joro@8bytes.org>

drivers/iommu/dmar.c

@@ -100,7 +100,6 @@ static int __init dmar_parse_one_dev_scope(struct acpi_dmar_device_scope *scope,
 	if (!pdev) {
 		pr_warn("Device scope device [%04x:%02x:%02x.%02x] not found\n",
 			segment, scope->bus, path->device, path->function);
-		*dev = NULL;
 		return 0;
 	}
 	if ((scope->entry_type == ACPI_DMAR_SCOPE_TYPE_ENDPOINT && \
@@ -151,7 +150,7 @@ int __init dmar_parse_dev_scope(void *start, void *end, int *cnt,
 			ret = dmar_parse_one_dev_scope(scope,
 				&(*devices)[index], segment);
 			if (ret) {
-				kfree(*devices);
+				dmar_free_dev_scope(devices, cnt);
 				return ret;
 			}
 			index ++;
@@ -162,6 +161,17 @@ int __init dmar_parse_dev_scope(void *start, void *end, int *cnt,
 	return 0;
 }
 
+void dmar_free_dev_scope(struct pci_dev ***devices, int *cnt)
+{
+	if (*devices && *cnt) {
+		while (--*cnt >= 0)
+			pci_dev_put((*devices)[*cnt]);
+		kfree(*devices);
+		*devices = NULL;
+		*cnt = 0;
+	}
+}
+
 /**
  * dmar_parse_one_drhd - parses exactly one DMA remapping hardware definition
  * structure which uniquely represent one DMA remapping hardware unit

include/linux/dmar.h

@@ -62,6 +62,9 @@ extern struct list_head dmar_drhd_units;
 
 extern int dmar_table_init(void);
 extern int dmar_dev_scope_init(void);
+extern int dmar_parse_dev_scope(void *start, void *end, int *cnt,
+				struct pci_dev ***devices, u16 segment);
+extern void dmar_free_dev_scope(struct pci_dev ***devices, int *cnt);
 
 /* Intel IOMMU detection */
 extern int detect_intel_iommu(void);
@@ -157,8 +160,6 @@ struct dmar_atsr_unit {
 int dmar_parse_rmrr_atsr_dev(void);
 extern int dmar_parse_one_rmrr(struct acpi_dmar_header *header);
 extern int dmar_parse_one_atsr(struct acpi_dmar_header *header);
-extern int dmar_parse_dev_scope(void *start, void *end, int *cnt,
-				struct pci_dev ***devices, u16 segment);
 extern int intel_iommu_init(void);
 #else /* !CONFIG_INTEL_IOMMU: */
 static inline int intel_iommu_init(void) { return -ENODEV; }