Re: [PATCH v5 4/9] rust: device: Enable printing fwnode name and path

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

On Tue, May 20, 2025 at 10:00:19PM +0200, Remo Senekowitsch wrote:
> Add two new public methods `display_name` and `display_path` to
> `FwNode`. They can be used by driver authors for logging purposes. In
> addition, they will be used by core property abstractions for automatic
> logging, for example when a driver attempts to read a required but
> missing property.
> 
> Signed-off-by: Remo Senekowitsch <remo@buenzli.dev>
> ---
>  rust/kernel/device/property.rs | 72 ++++++++++++++++++++++++++++++++++
>  1 file changed, 72 insertions(+)
> 
> diff --git a/rust/kernel/device/property.rs b/rust/kernel/device/property.rs
> index 70593343bd811..6ccc7947f9c31 100644
> --- a/rust/kernel/device/property.rs
> +++ b/rust/kernel/device/property.rs
> @@ -32,6 +32,78 @@ pub(crate) fn as_raw(&self) -> *mut bindings::fwnode_handle {
>          self.0.get()
>      }
>  
> +    /// Returns an object that implements [`Display`](core::fmt::Display) for
> +    /// printing the name of a node.
> +    pub fn display_name(&self) -> impl core::fmt::Display + '_ {
> +        struct FwNodeDisplayName<'a>(&'a FwNode);
> +
> +        impl core::fmt::Display for FwNodeDisplayName<'_> {
> +            fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
> +                // SAFETY: self is valid by its type invariant
> +                let name = unsafe { bindings::fwnode_get_name(self.0.as_raw()) };
> +                if name.is_null() {
> +                    return Ok(());

So if there is no name, you are returning Ok()?  Are you sure that's ok
to do?  What will the result of the string look like then?

thanks,

greg k-h