[PATCH] extcon: realtek: Use scope-based resource management in extcon_rtk_type_c_init()

[PATCH] extcon: realtek: Use scope-based resource management in extcon_rtk_type_c_init()

[Markus Elfring]

From: Markus Elfring <elfring@users.sourceforge.net>
Date: Tue, 4 Jun 2024 21:55:08 +0200

Scope-based resource management became supported also for another
programming interface by contributions of Jonathan Cameron on 2024-02-17.
See also the commit 59ed5e2d505bf5f9b4af64d0021cd0c96aec1f7c ("device
property: Add cleanup.h based fwnode_handle_put() scope based cleanup.").

* Thus use the attribute “__free(fwnode_handle)”.

* Reduce the scope for the local variable “fwnode”.

Fixes: 8a590d7371f0 ("extcon: add Realtek DHC RTD SoC Type-C driver")
Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
---
 drivers/extcon/extcon-rtk-type-c.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/extcon/extcon-rtk-type-c.c b/drivers/extcon/extcon-rtk-type-c.c
index 19a01e663733..8a4b074fd745 100644
--- a/drivers/extcon/extcon-rtk-type-c.c
+++ b/drivers/extcon/extcon-rtk-type-c.c
@@ -18,6 +18,7 @@
 #include <linux/syscalls.h>
 #include <linux/suspend.h>
 #include <linux/debugfs.h>
+#include <linux/property.h>
 #include <linux/extcon.h>
 #include <linux/extcon-provider.h>
 #include <linux/sys_soc.h>
@@ -1237,7 +1238,6 @@ static int extcon_rtk_type_c_init(struct type_c_data *type_c)

 	if (!type_c->port) {
 		struct typec_capability typec_cap = { };
-		struct fwnode_handle *fwnode;
 		const char *buf;
 		int ret;

@@ -1246,7 +1246,8 @@ static int extcon_rtk_type_c_init(struct type_c_data *type_c)
 		typec_cap.driver_data = type_c;
 		typec_cap.ops = &type_c_port_ops;

-		fwnode = device_get_named_child_node(dev, "connector");
+		struct fwnode_handle *fwnode __free(fwnode_handle)
+					     = device_get_named_child_node(dev, "connector");
 		if (!fwnode)
 			return -EINVAL;

--
2.45.1

Re: [PATCH] extcon: realtek: Use scope-based resource management in extcon_rtk_type_c_init()

[Andy Shevchenko]

On Tue, Jun 04, 2024 at 10:06:14PM +0200, Markus Elfring wrote:
> From: Markus Elfring <elfring@users.sourceforge.net>
> Date: Tue, 4 Jun 2024 21:55:08 +0200
> 
> Scope-based resource management became supported also for another
> programming interface by contributions of Jonathan Cameron on 2024-02-17.
> See also the commit 59ed5e2d505bf5f9b4af64d0021cd0c96aec1f7c ("device
> property: Add cleanup.h based fwnode_handle_put() scope based cleanup.").
> 
> * Thus use the attribute “__free(fwnode_handle)”.
> 
> * Reduce the scope for the local variable “fwnode”.

> Fixes: 8a590d7371f0 ("extcon: add Realtek DHC RTD SoC Type-C driver")

The problem here is that the above mentioned API only recently appeared in the
kernel. It will be impossible to backport without backporting a new API, which
is usually contradicts the idea of stable kernels. That's why it's better to
really fix without using a new APIs and then convert to a new one. Hence needs
two patches.

-- 
With Best Regards,
Andy Shevchenko

[PATCH v2] extcon: realtek: Prevent resource leak in extcon_rtk_type_c_init()

[Markus Elfring]

From: Markus Elfring <elfring@users.sourceforge.net>
Date: Sat, 29 Jun 2024 11:30:06 +0200

The API documentation for the function “device_get_named_child_node”
contains the following information:
“…
The caller is responsible for calling fwnode_handle_put()
on the returned fwnode pointer.
…”

The mentioned requirement was not fulfilled so that a resource leak
will occur in error cases after a device_get_named_child_node() call
succeeded in this function implementation.

Thus apply scope-based resource management which became supported also
for this programming interface by contributions of Jonathan Cameron
on 2024-02-17.
See also the commit 59ed5e2d505bf5f9b4af64d0021cd0c96aec1f7c ("device
property: Add cleanup.h based fwnode_handle_put() scope based cleanup.").

* Use the attribute “__free(fwnode_handle)” accordingly.

* Reduce the scope for the local variable “fwnode”.

Cc: stable@vger.kernel.org
Fixes: 8a590d7371f0 ("extcon: add Realtek DHC RTD SoC Type-C driver")
Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
---

V2:
* The change description was extended.

* The summary phrase was adjusted.

* A “stable tag” was added.


I guess that clarifications can become interesting also for backporting concerns
because of the proposed software transformation.



 drivers/extcon/extcon-rtk-type-c.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/extcon/extcon-rtk-type-c.c b/drivers/extcon/extcon-rtk-type-c.c
index 19a01e663733..8a4b074fd745 100644
--- a/drivers/extcon/extcon-rtk-type-c.c
+++ b/drivers/extcon/extcon-rtk-type-c.c
@@ -18,6 +18,7 @@
 #include <linux/syscalls.h>
 #include <linux/suspend.h>
 #include <linux/debugfs.h>
+#include <linux/property.h>
 #include <linux/extcon.h>
 #include <linux/extcon-provider.h>
 #include <linux/sys_soc.h>
@@ -1237,7 +1238,6 @@ static int extcon_rtk_type_c_init(struct type_c_data *type_c)

 	if (!type_c->port) {
 		struct typec_capability typec_cap = { };
-		struct fwnode_handle *fwnode;
 		const char *buf;
 		int ret;

@@ -1246,7 +1246,8 @@ static int extcon_rtk_type_c_init(struct type_c_data *type_c)
 		typec_cap.driver_data = type_c;
 		typec_cap.ops = &type_c_port_ops;

-		fwnode = device_get_named_child_node(dev, "connector");
+		struct fwnode_handle *fwnode __free(fwnode_handle)
+					     = device_get_named_child_node(dev, "connector");
 		if (!fwnode)
 			return -EINVAL;

--
2.45.2