iommu/arm-smmu: Correct group reference count

The basic flow for add a device:
 arm_smmu_add_device
        |->iommu_group_get_for_dev
            |->iommu_group_get
                     return group;  (1)
            |->ops->device_group : Init/increase reference count to/by 1.
            |->iommu_group_add_device : Increase reference count by 1.
		     return group   (2)
        |->return 0;

Since we are adding one device, the flow is (2) and the group reference
count will be increased by 2. So, we need to add iommu_group_put at the
end of arm_smmu_add_device to decrease the count by 1.

Also take the failure path into consideration when fail to add a device.

Signed-off-by: Peng Fan <van.freenix@gmail.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

2 files changed, 12 insertions, 7 deletions

diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c
index 2e3e235f509c..3ea4d576bf08 100644
--- a/drivers/iommu/arm-smmu-v3.c
+++ b/drivers/iommu/arm-smmu-v3.c
@@ -1809,13 +1809,13 @@ static int arm_smmu_add_device(struct device *dev)
                 smmu = arm_smmu_get_for_pci_dev(pdev);
                 if (!smmu) {
                         ret = -ENOENT;
-                        goto out_put_group;
+                        goto out_remove_dev;
                 }
 
                 smmu_group = kzalloc(sizeof(*smmu_group), GFP_KERNEL);
                 if (!smmu_group) {
                         ret = -ENOMEM;
-                        goto out_put_group;
+                        goto out_remove_dev;
                 }
 
                 smmu_group->ste.valid   = true;
@@ -1831,20 +1831,20 @@ static int arm_smmu_add_device(struct device *dev)
         for (i = 0; i < smmu_group->num_sids; ++i) {
                 /* If we already know about this SID, then we're done */
                 if (smmu_group->sids[i] == sid)
-                        return 0;
+                        goto out_put_group;
         }
 
         /* Check the SID is in range of the SMMU and our stream table */
         if (!arm_smmu_sid_in_range(smmu, sid)) {
                 ret = -ERANGE;
-                goto out_put_group;
+                goto out_remove_dev;
         }
 
         /* Ensure l2 strtab is initialised */
         if (smmu->features & ARM_SMMU_FEAT_2_LVL_STRTAB) {
                 ret = arm_smmu_init_l2_strtab(smmu, sid);
                 if (ret)
-                        goto out_put_group;
+                        goto out_remove_dev;
         }
 
         /* Resize the SID array for the group */
@@ -1854,16 +1854,20 @@ static int arm_smmu_add_device(struct device *dev)
         if (!sids) {
                 smmu_group->num_sids--;
                 ret = -ENOMEM;
-                goto out_put_group;
+                goto out_remove_dev;
         }
 
         /* Add the new SID */
         sids[smmu_group->num_sids - 1] = sid;
         smmu_group->sids = sids;
-        return 0;
 
 out_put_group:
         iommu_group_put(group);
+        return 0;
+
+out_remove_dev:
+        iommu_group_remove_device(dev);
+        iommu_group_put(group);
         return ret;
 }
 
diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
index 1ce4b85d5216..6ed169bcb39d 100644
--- a/drivers/iommu/arm-smmu.c
+++ b/drivers/iommu/arm-smmu.c
@@ -1355,6 +1355,7 @@ static int arm_smmu_add_device(struct device *dev)
         if (IS_ERR(group))
                 return PTR_ERR(group);
 
+        iommu_group_put(group);
         return 0;
 }