linux-kernel - Re: [PATCH v3 1/2] device property: Add scoped fwnode child node iterators

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Message-ID: <9ed3743b-4f86-42d3-94e0-8a720526dce4@kernel.org>
Date: Mon, 1 Sep 2025 19:48:14 +0200
From: Danilo Krummrich <dakr@...nel.org>
To: Jean-François Lessard <jefflessard3@...il.com>
Cc: Wolfram Sang <wsa+renesas@...g-engineering.com>,
 Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
 Daniel Scally <djrscally@...il.com>,
 Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
 Sakari Ailus <sakari.ailus@...ux.intel.com>,
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
 "Rafael J. Wysocki" <rafael@...nel.org>, Danilo Krummrich <dakr@...nel.org>,
 linux-i2c@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-acpi@...r.kernel.org
Subject: Re: [PATCH v3 1/2] device property: Add scoped fwnode child node
 iterators

On 9/1/25 6:36 PM, Jean-François Lessard wrote:
> Add scoped versions of fwnode child node iterators that automatically
> handle reference counting cleanup using the __free() attribute:
> 
> - fwnode_for_each_child_node_scoped()
> - fwnode_for_each_named_child_node_scoped()
> - fwnode_for_each_available_child_node_scoped()
> 
> These macros follow the same pattern as existing scoped iterators in the
> kernel, ensuring fwnode references are automatically released when the
> iterator variable goes out of scope. This prevents resource leaks and
> eliminates the need for manual cleanup in error paths.
> 
> The implementation mirrors the non-scoped variants but uses
> __free(fwnode_handle) for automatic resource management, providing a
> safer and more convenient interface for drivers iterating over firmware
> node children.
> 
> Signed-off-by: Jean-François Lessard <jefflessard3@...il.com>

Thanks for adding a user and splitting it up (Andy was a bit faster than me :).

> diff --git a/include/linux/property.h b/include/linux/property.h
> index 82f0cb3ab..279c244db 100644
> --- a/include/linux/property.h
> +++ b/include/linux/property.h
> @@ -176,6 +176,20 @@ struct fwnode_handle *fwnode_get_next_available_child_node(
>   	for (child = fwnode_get_next_available_child_node(fwnode, NULL); child;\
>   	     child = fwnode_get_next_available_child_node(fwnode, child))
>   
> +#define fwnode_for_each_child_node_scoped(fwnode, child)		\
> +	for (struct fwnode_handle *child __free(fwnode_handle) =	\
> +		fwnode_get_next_child_node(fwnode, NULL);		\
> +	     child; child = fwnode_get_next_child_node(fwnode, child))
> +
> +#define fwnode_for_each_named_child_node_scoped(fwnode, child, name)	\
> +	fwnode_for_each_child_node_scoped(fwnode, child)		\
> +		for_each_if(fwnode_name_eq(child, name))

IIRC, your first patch mentioned that your driver series would only use
fwnode_for_each_available_child_node_scoped().

And this series adds a user for fwnode_for_each_child_node_scoped(); do you also 
have a user for fwnode_for_each_named_child_node_scoped()?