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vfio: fix noiommu vfio_iommu_group_get reference count 

In vfio_iommu_group_get() we want to increase the reference
count of the iommu group.

In noiommu case, the group does not exist and is allocated.
iommu_group_add_device() increases the group ref count. However we
then call iommu_group_put() which decrements it.

This leads to a "refcount_t: underflow WARN_ON".

Only decrement the ref count in case of iommu_group_add_device
failure.

Signed-off-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
This commit is contained in:
Eric Auger 2017-08-11 15:16:06 +02:00 committed by Alex Williamson
parent f203f7f1db
commit d935ad91f0
1 changed files with 3 additions and 2 deletions
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3
drivers/vfio/vfio.c
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@ -138,9 +138,10 @@ struct iommu_group *vfio_iommu_group_get(struct device *dev)
iommu_group_set_name(group, "vfio-noiommu");
iommu_group_set_iommudata(group, &noiommu, NULL);
ret = iommu_group_add_device(group, dev);
if (ret) {
iommu_group_put(group);
if (ret)
return NULL;
}
/*
* Where to taint? At this point we've added an IOMMU group for a