linux-kernel - [PATCH 2] usb: typec: anx7411: Use scope-based resource management in anx7411_typec_port

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Date: Fri, 28 Jun 2024 09:26:47 +0200
From: Markus Elfring <Markus.Elfring@....de>
To: linux-usb@...r.kernel.org, kernel-janitors@...r.kernel.org,
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
 Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
 Jonathan Cameron <Jonathan.Cameron@...wei.com>, Xin Ji <xji@...logixsemi.com>
Cc: LKML <linux-kernel@...r.kernel.org>, Julia Lawall <julia.lawall@...ia.fr>
Subject: [PATCH 2] usb: typec: anx7411: Use scope-based resource management in
 anx7411_typec_port_probe()

From: Markus Elfring <elfring@...rs.sourceforge.net>
Date: Fri, 28 Jun 2024 08:25:34 +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 some 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@...r.kernel.org
Fixes: fe6d8a9c8e64 ("usb: typec: anx7411: Add Analogix PD ANX7411 support")
Reviewed-by: Heikki Krogerus <heikki.krogerus@...ux.intel.com>
Signed-off-by: Markus Elfring <elfring@...rs.sourceforge.net>
---

V2:
* The change description was extended as requested by patch reviewers.

* The tag “Reviewed-by” was added according to feedback by Heikki Krogerus.

* A “stable tag” was added.

V1:
Initial patch review
https://lore.kernel.org/r/889729ac-3fc5-4666-b9f5-ce6e588a341a@web.de/
https://lkml.org/lkml/2024/6/5/1276

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

 drivers/usb/typec/anx7411.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/usb/typec/anx7411.c b/drivers/usb/typec/anx7411.c
index b12a07edc71b..9fb52f233a30 100644
--- a/drivers/usb/typec/anx7411.c
+++ b/drivers/usb/typec/anx7411.c
@@ -16,6 +16,7 @@
 #include <linux/of_graph.h>
 #include <linux/of_platform.h>
 #include <linux/pm_runtime.h>
+#include <linux/property.h>
 #include <linux/regulator/consumer.h>
 #include <linux/slab.h>
 #include <linux/types.h>
@@ -1142,11 +1143,11 @@ static int anx7411_typec_port_probe(struct anx7411_data *ctx,
 {
 	struct typec_capability *cap = &ctx->typec.caps;
 	struct typec_params *typecp = &ctx->typec;
-	struct fwnode_handle *fwnode;
 	const char *buf;
 	int ret, i;

-	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;

@@ -1237,7 +1238,7 @@ static int anx7411_typec_port_probe(struct anx7411_data *ctx,
 		typecp->caps_flags |= HAS_SINK_WATT;
 	}

-	cap->fwnode = fwnode;
+	cap->fwnode = no_free_ptr(fwnode);

 	ctx->typec.role_sw = usb_role_switch_get(dev);
 	if (IS_ERR(ctx->typec.role_sw)) {
--
2.45.2