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[v4,04/15] device property: Introduce device_for_each_child_node_scoped()

Message ID 20240217164249.921878-5-jic23@kernel.org
State New
Headers show
Series device property / IIO: Use cleanup.h magic for fwnode_handle_put() handling. | expand

Commit Message

Jonathan Cameron Feb. 17, 2024, 4:42 p.m. UTC
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(+)

Comments

Greg Kroah-Hartman Feb. 19, 2024, 8:56 a.m. UTC | #1
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>
Sakari Ailus Feb. 20, 2024, 6:59 a.m. UTC | #2
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>

Reviewed-by: Sakari Ailus <sakari.ailus@linux.intel.com>
diff mbox series

Patch

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,