On Fri, Apr 17, 2020 at 9:54 AM Nicolas Saenz Julienne
<nsaenzjulienne@xxxxxxx> wrote:
>
> 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@xxxxxxx>
>
> ---
>
> Changes since v1:
> - Move availability check into the compatible search routine and bail
> if device node disabled
>
> drivers/of/property.c | 19 ++++++++++++++++++-
> 1 file changed, 18 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/of/property.c b/drivers/of/property.c
> index dc034eb45defd..14b6266dd054b 100644
> --- a/drivers/of/property.c
> +++ b/drivers/of/property.c
> @@ -1045,8 +1045,25 @@ 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 a device node as consumer of a disabled
> + * node.
> + */
Minor nit: I'd just say "Don't allow linking to a disabled supplier".
> + if (!of_device_is_available(sup_np)) {
> + dev_dbg(dev, "Not linking to %pOFP - Not available\n",
> + sup_np);
> + of_node_put(sup_np);
> + return -ENODEV;
> + }
This if block looks very similar to the one right after the loop.
Maybe there's a nice way to combine it?
If you replace this if block with this, it'll end up with the same result.
if (!of_device_is_available(sup_np)) {
of_node_put(sup_np);
sup_np = NULL;
}
of_get_next_parent() handles a NULL input properly. So that won't be a
problem. And "No device" is a valid statement for both cases I think.
> +
> + 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;
However, not against this patch as is if Rob/Frank like it as is.
-Saravana
