iommu: Warn once when device_group callback returns NULL

This callback should never return NULL. Print a warning if
that happens so that we notice and can fix it.

Signed-off-by: Joerg Roedel <jroedel@suse.de>

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index de09e1e..3f6ea16 100644 (file)
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -1010,6 +1010,9 @@ struct iommu_group *iommu_group_get_for_dev(struct device *dev)
        if (ops && ops->device_group)
                group = ops->device_group(dev);
 
+       if (WARN_ON_ONCE(group == NULL))
+               return ERR_PTR(-EINVAL);
+
        if (IS_ERR(group))
                return group;