Re: [PATCH v4 04/15] device property: Introduce device_for_each_child_node_scoped() - Greg Kroah-Hartman

From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: Jonathan Cameron <jic23@kernel.org>
Cc: linux-iio@vger.kernel.org,
	"Rafael J . Wysocki" <rafael@kernel.org>,
	"Len Brown" <lenb@kernel.org>,
	linux-acpi@vger.kernel.org,
	"Andy Shevchenko" <andriy.shevchenko@linux.intel.com>,
	"Daniel Scally" <djrscally@gmail.com>,
	"Heikki Krogerus" <heikki.krogerus@linux.intel.com>,
	"Sakari Ailus" <sakari.ailus@linux.intel.com>,
	"Julia Lawall" <Julia.Lawall@inria.fr>,
	"Nuno Sá" <nuno.sa@analog.com>,
	"Cosmin Tanislav" <cosmin.tanislav@analog.com>,
	"Mihail Chindris" <mihail.chindris@analog.com>,
	"Rasmus Villemoes" <linux@rasmusvillemoes.dk>,
	"Tomislav Denis" <tomislav.denis@avl.com>,
	"Marek Vasut" <marex@denx.de>,
	"Olivier Moysan" <olivier.moysan@foss.st.com>,
	"Fabrice Gasnier" <fabrice.gasnier@foss.st.com>,
	"Lad Prabhakar" <prabhakar.mahadev-lad.rj@bp.renesas.com>,
	"Dmitry Baryshkov" <dmitry.baryshkov@linaro.org>,
	"Marijn Suijten" <marijn.suijten@somainline.org>,
	"Marius Cristea" <marius.cristea@microchip.com>,
	"Ibrahim Tilki" <Ibrahim.Tilki@analog.com>,
	"Peter Zijlstra" <peterz@infradead.org>,
	"Jonathan Cameron" <Jonathan.Cameron@huawei.com>
Subject: Re: [PATCH v4 04/15] device property: Introduce device_for_each_child_node_scoped()
Date: Mon, 19 Feb 2024 09:56:12 +0100	[thread overview]
Message-ID: <2024021904-subgroup-activist-442c@gregkh> (raw)
In-Reply-To: <20240217164249.921878-5-jic23@kernel.org>

On Sat, Feb 17, 2024 at 04:42:38PM +0000, Jonathan Cameron wrote:
> From: Jonathan Cameron <Jonathan.Cameron@huawei.com>
> 
> 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.
> 
> Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
> ---
> v4: Include the alignement changes that were in patch 15 of v3 with
>     a tweak as I missed the first line. Thanks Andy!
> 
>  include/linux/property.h | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/include/linux/property.h b/include/linux/property.h
> index 9e67c3c4df6e..eefd662a2f9d 100644
> --- a/include/linux/property.h
> +++ b/include/linux/property.h
> @@ -182,6 +182,11 @@ 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,

Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>