linux-kernel - [PATCH v2 0/3] device property: introduce fwnode_for_each_available_child_node

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Message-Id: <20240523-fwnode_for_each_available_child_node_scoped-v2-0-701f3a03f2fb@gmail.com>
Date: Thu, 23 May 2024 17:47:13 +0200
From: Javier Carrasco <javier.carrasco.cruz@...il.com>
To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>, 
 "Rafael J. Wysocki" <rafael@...nel.org>, 
 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>, 
 Jean Delvare <jdelvare@...e.com>, Guenter Roeck <linux@...ck-us.net>, 
 Antoniu Miclaus <antoniu.miclaus@...log.com>, 
 Jonathan Cameron <jic23@...nel.org>
Cc: linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org, 
 linux-hwmon@...r.kernel.org, 
 Javier Carrasco <javier.carrasco.cruz@...il.com>, stable@...r.kernel.org
Subject: [PATCH v2 0/3] device property: introduce
 fwnode_for_each_available_child_node_scoped()

The _scoped() version of the fwnode_for_each_available_child_node()
follows the approach recently taken for other loops that handle child
nodes like for_each_child_of_node_scoped() or
device_for_each_child_node_scoped(), which are based on the __free()
auto cleanup handler to remove the need for fwnode_handle_put() on
early loop exits.

This new variant has been tested with the LTC2992, which currently uses
the non-scoped variant. There is one error path that does not decrement
the refcount of the child node, which can be fixed by using the new
macro. The bug was introduced in a later modification of the loop, which
shows how useful an automatic cleanup solution can be in many uses of
the non-scoped version.

In order to provide a backportable patch, the conversion in the LTC2992
driver is carried out in two steps: first the missing
fwnode_handle_put() is added, and then the code is refactored to adopt
the new, safer approach.

@Andy Shevchenko: I kept your Reviewed-by in 3/3, that now also removes
the new fwnode_handle_put() and braces added with 1/3.

Signed-off-by: Javier Carrasco <javier.carrasco.cruz@...il.com>
---
Changes in v2:
- Fix the memory leak in a backportable patch and tag it for stable.
- Refactor 1/3 with 3/3 as well.
- Link to v1: https://lore.kernel.org/r/20240522-fwnode_for_each_available_child_node_scoped-v1-0-1188b0da12dc@gmail.com

---
Javier Carrasco (3):
      hwmon: (ltc2992) Fix memory leak in ltc2992_parse_dt()
      device property: introduce fwnode_for_each_available_child_node_scoped()
      hwmon: (ltc2992) Use fwnode_for_each_available_child_node_scoped()

 drivers/hwmon/ltc2992.c  | 11 +++--------
 include/linux/property.h |  5 +++++
 2 files changed, 8 insertions(+), 8 deletions(-)
---
base-commit: 124cfbcd6d185d4f50be02d5f5afe61578916773
change-id: 20240521-fwnode_for_each_available_child_node_scoped-8f1f09d3a10c

Best regards,
-- 
Javier Carrasco <javier.carrasco.cruz@...il.com>