of: property: Do not link to disabled devices

When creating a consumer/supplier relationship between two devices,
make sure the supplier node is actually active. Otherwise this will
create a link relationship that will never be fulfilled. This, in the
worst case scenario, will hang the system during boot.

Note that, in practice, the fact that a device-tree represented
consumer/supplier relationship isn't fulfilled will not prevent devices
from successfully probing.

Fixes: a3e1d1a7f5fc ("of: property: Add functional dependency link from DT bindings")
Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Reviewed-by: Saravana Kannan <saravanak@google.com>
Signed-off-by: Rob Herring <robh@kernel.org>

diff --git a/drivers/of/property.c b/drivers/of/property.c
index 9674b3c..1f2086f 100644 (file)
--- a/drivers/of/property.c
+++ b/drivers/of/property.c
@@ -1045,8 +1045,20 @@ static int of_link_to_phandle(struct device *dev, struct device_node *sup_np,
         * Find the device node that contains the supplier phandle.  It may be
         * @sup_np or it may be an ancestor of @sup_np.
         */
-       while (sup_np && !of_find_property(sup_np, "compatible", NULL))
+       while (sup_np) {
+
+               /* Don't allow linking to a disabled supplier */
+               if (!of_device_is_available(sup_np)) {
+                       of_node_put(sup_np);
+                       sup_np = NULL;
+               }
+
+               if (of_find_property(sup_np, "compatible", NULL))
+                       break;
+
                sup_np = of_get_next_parent(sup_np);
+       }
+
        if (!sup_np) {
                dev_dbg(dev, "Not linking to %pOFP - No device\n", tmp_np);
                return -ENODEV;