iommu: Improve error handling when setting bus iommu

When some part of bus_set_iommu fails it should undo any made changes
and not simply leave everything as is.

This includes unregistering the bus notifier in iommu_bus_init when
add_iommu_group fails and also setting the bus->iommu_ops back to NULL.

Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: Joerg Roedel <jroedel@suse.de>

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 08c53c5a046f267502e26c5b7f918e88ee05dea7..02e4313e937c3f281d8077a20e60e9c616da4c18 100644 (file)
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -818,7 +818,15 @@ static int iommu_bus_init(struct bus_type *bus, const struct iommu_ops *ops)
                kfree(nb);
                return err;
        }
-       return bus_for_each_dev(bus, NULL, &cb, add_iommu_group);
+
+       err = bus_for_each_dev(bus, NULL, &cb, add_iommu_group);
+       if (err) {
+               bus_unregister_notifier(bus, nb);
+               kfree(nb);
+               return err;
+       }
+
+       return 0;
 }
 
 /**
@@ -836,13 +844,19 @@ static int iommu_bus_init(struct bus_type *bus, const struct iommu_ops *ops)
  */
 int bus_set_iommu(struct bus_type *bus, const struct iommu_ops *ops)
 {
+       int err;
+
        if (bus->iommu_ops != NULL)
                return -EBUSY;
 
        bus->iommu_ops = ops;
 
        /* Do IOMMU specific setup for this bus-type */
-       return iommu_bus_init(bus, ops);
+       err = iommu_bus_init(bus, ops);
+       if (err)
+               bus->iommu_ops = NULL;
+
+       return err;
 }
 EXPORT_SYMBOL_GPL(bus_set_iommu);