The basic flow for iommu_group_for_dev is:
iommu_group_get_for_dev
|-> iommu_group_get : increase reference count by 1.
return group;
|-> ops->device_group : Init/increase reference count to/by 1.
iommu_group_add_device : Increase reference count by 1.
return group;
We can see that ops->device_group and iommu_group_add_device will together
increase the iommu group reference count by 2. Actually we only need 1,
but not 2. So we need add iommu_group_put after iommu_group_add_device
to make sure iommu_group_get_for_dev only increase reference count by 1.
Signed-off-by: Peng Fan <van.free...@gmail.com>
Cc: Joerg Roedel <j...@8bytes.org>
Cc: Will Deacon <will.dea...@arm.com>
---
V1 thread: https://lkml.org/lkml/2015/11/3/304
Changes V2:
I did not see the update about device_group when I worked out V1. So
redo the patch and refine commit msg and rebased to latest linus'
linux master tree.
drivers/iommu/iommu.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index abae363..9c1971b 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -852,10 +852,10 @@ struct iommu_group *iommu_group_get_for_dev(struct device
*dev)
}
ret = iommu_group_add_device(group, dev);
- if (ret) {
- iommu_group_put(group);
+ iommu_group_put(group);
+
+ if (ret)
return ERR_PTR(ret);
- }
return group;
}
--
1.8.4
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