Messages in this thread Patch in this message | | | From | Peng Fan <> | Subject | [RFC V2] iommu: correct group reference count | Date | Mon, 9 Nov 2015 14:13:28 +0800 |
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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.freenix@gmail.com> Cc: Joerg Roedel <joro@8bytes.org> Cc: Will Deacon <will.deacon@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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