linux-kernel - [PATCH v2] usb: roles: add lockdep class key to struct usb_role

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Message-ID: <20240815044058.1493751-1-amitsd@google.com>
Date: Wed, 14 Aug 2024 21:40:55 -0700
From: Amit Sunil Dhamne <amitsd@...gle.com>
To: heikki.krogerus@...ux.intel.com, gregkh@...uxfoundation.org
Cc: badhri@...gle.com, linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org, 
	kyletso@...gle.com, rdbabiera@...gle.com, 
	Amit Sunil Dhamne <amitsd@...gle.com>
Subject: [PATCH v2] usb: roles: add lockdep class key to struct usb_role_switch

There can be multiple role switch devices running on a platform. Given
that lockdep is not capable of differentiating between locks of
different instances, false positive warnings for circular locking are
reported. To prevent this, register unique lockdep key for each of the
individual instances.

Signed-off-by: Amit Sunil Dhamne <amitsd@...gle.com>
---
v1->v2
- Avoid usage of ifdefs.
---
 drivers/usb/roles/class.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/drivers/usb/roles/class.c b/drivers/usb/roles/class.c
index d7aa913ceb8a..9dbe9f6bea83 100644
--- a/drivers/usb/roles/class.c
+++ b/drivers/usb/roles/class.c
@@ -11,6 +11,7 @@
 #include <linux/usb/role.h>
 #include <linux/property.h>
 #include <linux/device.h>
+#include <linux/lockdep.h>
 #include <linux/module.h>
 #include <linux/mutex.h>
 #include <linux/slab.h>
@@ -33,6 +34,8 @@ struct usb_role_switch {
 	usb_role_switch_set_t set;
 	usb_role_switch_get_t get;
 	bool allow_userspace_control;
+
+	struct lock_class_key key;
 };
 
 #define to_role_switch(d)	container_of(d, struct usb_role_switch, dev)
@@ -396,6 +399,11 @@ usb_role_switch_register(struct device *parent,
 
 	sw->registered = true;
 
+	if (IS_ENABLED(CONFIG_LOCKDEP)) {
+		lockdep_register_key(&sw->key);
+		lockdep_set_class(&sw->lock, &sw->key);
+	}
+
 	/* TODO: Symlinks for the host port and the device controller. */
 
 	return sw;
@@ -412,6 +420,10 @@ void usb_role_switch_unregister(struct usb_role_switch *sw)
 {
 	if (IS_ERR_OR_NULL(sw))
 		return;
+
+	if (IS_ENABLED(CONFIG_LOCKDEP))
+		lockdep_unregister_key(&sw->key);
+
 	sw->registered = false;
 	if (dev_fwnode(&sw->dev))
 		component_del(&sw->dev, &connector_ops);
-- 
2.46.0.76.ge559c4bf1a-goog