iommu: Tidy the control flow in iommu_group_store_type()

Use a normal "goto unwind" instead of trying to be clever with checking
!ret and manually managing the unlock.
Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Tested-by: Heiko Stuebner <heiko@sntech.de>
Tested-by: Niklas Schnelle <schnelle@linux.ibm.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/17-v5-1b99ae392328+44574-iommu_err_unwind_jgg@nvidia.comSigned-off-by: Joerg Roedel <jroedel@suse.de>

drivers/iommu/iommu.c

@@ -2940,6 +2940,7 @@ static int iommu_setup_default_domain(struct iommu_group *group,
 static ssize_t iommu_group_store_type(struct iommu_group *group,
 				      const char *buf, size_t count)
 {
+	struct group_device *gdev;
 	int ret, req_type;
 
 	if (!capable(CAP_SYS_ADMIN) || !capable(CAP_SYS_RAWIO))
@@ -2964,20 +2965,23 @@ static ssize_t iommu_group_store_type(struct iommu_group *group,
 	if (req_type == IOMMU_DOMAIN_DMA_FQ &&
 	    group->default_domain->type == IOMMU_DOMAIN_DMA) {
 		ret = iommu_dma_init_fq(group->default_domain);
-		if (!ret)
-			group->default_domain->type = IOMMU_DOMAIN_DMA_FQ;
-		mutex_unlock(&group->mutex);
+		if (ret)
+			goto out_unlock;
 
-		return ret ?: count;
+		group->default_domain->type = IOMMU_DOMAIN_DMA_FQ;
+		ret = count;
+		goto out_unlock;
 	}
 
 	/* Otherwise, ensure that device exists and no driver is bound. */
 	if (list_empty(&group->devices) || group->owner_cnt) {
-		mutex_unlock(&group->mutex);
-		return -EPERM;
+		ret = -EPERM;
+		goto out_unlock;
 	}
 
 	ret = iommu_setup_default_domain(group, req_type);
+	if (ret)
+		goto out_unlock;
 
 	/*
 	 * Release the mutex here because ops->probe_finalize() call-back of
@@ -2988,13 +2992,12 @@ static ssize_t iommu_group_store_type(struct iommu_group *group,
 	mutex_unlock(&group->mutex);
 
 	/* Make sure dma_ops is appropriatley set */
-	if (!ret) {
-		struct group_device *gdev;
-
 	for_each_group_device(group, gdev)
 		iommu_group_do_probe_finalize(gdev->dev);
-	}
+	return count;
 
+out_unlock:
+	mutex_unlock(&group->mutex);
 	return ret ?: count;
 }