device property: Introduce device_for_each_child_node_scoped()

JIRA: https://issues.redhat.com/browse/RHEL-66957
CVE: CVE-2024-50197

commit 365130f
Author: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Date:   Sat Feb 17 16:42:38 2024 +0000

    device property: Introduce device_for_each_child_node_scoped()

    Similar to recently propose for_each_child_of_node_scoped() this
    new version of the loop macro instantiates a new local
    struct fwnode_handle * that uses the __free(fwnode_handle) auto
    cleanup handling so that if a reference to a node is held on early
    exit from the loop the reference will be released. If the loop
    runs to completion, the child pointer will be NULL and no action will
    be taken.

    The reason this is useful is that it removes the need for
    fwnode_handle_put() on early loop exits.  If there is a need
    to retain the reference, then return_ptr(child) or no_free_ptr(child)
    may be used to safely disable the auto cleanup.

    Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    Reviewed-by: Sakari Ailus <sakari.ailus@linux.intel.com>
    Link: https://lore.kernel.org/r/20240217164249.921878-5-jic23@kernel.org
    Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

Signed-off-by: Steve Best <sbest@redhat.com>

Author: sfbest

include/linux/property.h

@@ -141,6 +141,11 @@ struct fwnode_handle *device_get_next_child_node(const struct device *dev,
 	for (child = device_get_next_child_node(dev, NULL); child;	\
 	     child = device_get_next_child_node(dev, child))
 
+#define device_for_each_child_node_scoped(dev, child)			\
+	for (struct fwnode_handle *child __free(fwnode_handle) =	\
+		device_get_next_child_node(dev, NULL);			\
+	     child; child = device_get_next_child_node(dev, child))
+
 struct fwnode_handle *fwnode_get_named_child_node(const struct fwnode_handle *fwnode,
 						  const char *childname);
 struct fwnode_handle *device_get_named_child_node(const struct device *dev,