[PATCH v3 13/34] iommu: Export bus_iommu_probe() and make is safe for re-probing

[Joerg Roedel <joro-zLv9SwRftAIdnm+yROfE0A@public.gmane.org>]

From: Joerg Roedel <jroedel-l3A5Bk7waGM@public.gmane.org>

Add a check to the bus_iommu_probe() call-path to make sure it ignores
devices which have already been successfully probed. Then export the
bus_iommu_probe() function so it can be used by IOMMU drivers.

Tested-by: Marek Szyprowski <m.szyprowski-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org>
Acked-by: Marek Szyprowski <m.szyprowski-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org>
Signed-off-by: Joerg Roedel <jroedel-l3A5Bk7waGM@public.gmane.org>
---
 drivers/iommu/iommu.c | 10 +++++++++-
 include/linux/iommu.h |  1 +
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 834a45da0ed0..397fd4fd0c32 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -1610,11 +1610,19 @@ static int probe_iommu_group(struct device *dev, void *data)
 {
 	const struct iommu_ops *ops = dev->bus->iommu_ops;
 	struct list_head *group_list = data;
+	struct iommu_group *group;
 	int ret;
 
 	if (!dev_iommu_get(dev))
 		return -ENOMEM;
 
+	/* Device is probed already if in a group */
+	group = iommu_group_get(dev);
+	if (group) {
+		iommu_group_put(group);
+		return 0;
+	}
+
 	if (!try_module_get(ops->owner)) {
 		ret = -EINVAL;
 		goto err_free_dev_iommu;
@@ -1783,7 +1791,7 @@ static int iommu_group_create_direct_mappings(struct iommu_group *group)
 					  iommu_do_create_direct_mappings);
 }
 
-static int bus_iommu_probe(struct bus_type *bus)
+int bus_iommu_probe(struct bus_type *bus)
 {
 	const struct iommu_ops *ops = bus->iommu_ops;
 	int ret;
diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 30170d191e5e..fea1622408ad 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -445,6 +445,7 @@ static inline void iommu_iotlb_gather_init(struct iommu_iotlb_gather *gather)
 #define IOMMU_GROUP_NOTIFY_UNBOUND_DRIVER	6 /* Post Driver unbind */
 
 extern int bus_set_iommu(struct bus_type *bus, const struct iommu_ops *ops);
+extern int bus_iommu_probe(struct bus_type *bus);
 extern bool iommu_present(struct bus_type *bus);
 extern bool iommu_capable(struct bus_type *bus, enum iommu_cap cap);
 extern struct iommu_domain *iommu_domain_alloc(struct bus_type *bus);
-- 
2.17.1