Re: [PATCH] iommu: Fix group refcount in iommu_alloc_default_domain()

From: Sai Prakash Ranjan
Date: Mon May 25 2020 - 09:10:47 EST

Hi Joerg,

On 2020-05-25 18:32, Joerg Roedel wrote:

On Fri, May 22, 2020 at 06:31:45PM +0530, Sai Prakash Ranjan wrote:
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index a4c2f122eb8b..05f7b77c432f 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -1491,6 +1491,7 @@ static int iommu_alloc_default_domain(struct device *dev)
struct iommu_group *group;
unsigned int type;
+ int ret;

group = iommu_group_get(dev);
if (!group)
@@ -1501,7 +1502,11 @@ static int iommu_alloc_default_domain(struct device *dev)

type = iommu_get_def_domain_type(dev);

- return iommu_group_alloc_default_domain(dev->bus, group, type);
+ ret = iommu_group_alloc_default_domain(dev->bus, group, type);
+ iommu_group_put(group);
+ return ret;


Thanks for the report and the fix. I think it is better to fix this by
not taking a group reference in iommu_alloc_default_domain() at all and
pass group as a parameter. Please see the patch I just sent out.

Thanks for the patch, it looks like the right thing to do. Testing it
out now.


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