3 files changed, 98 insertions, 24 deletions

diff --git a/Documentation/networking/devlink/index.rst b/Documentation/networking/devlink/index.rst
index 443123772f44..c17cdb079611 100644
--- a/Documentation/networking/devlink/index.rst
+++ b/Documentation/networking/devlink/index.rst
@@ -4,6 +4,22 @@ Linux Devlink Documentation
 devlink is an API to expose device information and resources not directly
 related to any device class, such as chip-wide/switch-ASIC-wide configuration.
 
+Locking
+-------
+
+Driver facing APIs are currently transitioning to allow more explicit
+locking. Drivers can use the existing ``devlink_*`` set of APIs, or
+new APIs prefixed by ``devl_*``. The older APIs handle all the locking
+in devlink core, but don't allow registration of most sub-objects once
+the main devlink object is itself registered. The newer ``devl_*`` APIs assume
+the devlink instance lock is already held. Drivers can take the instance
+lock by calling ``devl_lock()``. It is also held in most of the callbacks.
+Eventually all callbacks will be invoked under the devlink instance lock,
+refer to the use of the ``DEVLINK_NL_FLAG_NO_LOCK`` flag in devlink core
+to find out which callbacks are not converted, yet.
+
+Drivers are encouraged to use the devlink instance lock for their own needs.
+
 Interface documentation
 -----------------------
 
diff --git a/include/net/devlink.h b/include/net/devlink.h
index 8d5349d2fb68..9de0d091aee9 100644
--- a/include/net/devlink.h
+++ b/include/net/devlink.h
@@ -1479,6 +1479,17 @@ void *devlink_priv(struct devlink *devlink);
 struct devlink *priv_to_devlink(void *priv);
 struct device *devlink_to_dev(const struct devlink *devlink);
 
+/* Devlink instance explicit locking */
+void devl_lock(struct devlink *devlink);
+void devl_unlock(struct devlink *devlink);
+void devl_assert_locked(struct devlink *devlink);
+bool devl_lock_is_held(struct devlink *devlink);
+
+int devl_port_register(struct devlink *devlink,
+		       struct devlink_port *devlink_port,
+		       unsigned int port_index);
+void devl_port_unregister(struct devlink_port *devlink_port);
+
 struct ib_device;
 
 struct net *devlink_net(const struct devlink *devlink);
diff --git a/net/core/devlink.c b/net/core/devlink.c
index fcd9f6d85cf1..769e5f7fa219 100644
--- a/net/core/devlink.c
+++ b/net/core/devlink.c
@@ -225,6 +225,33 @@ struct devlink *__must_check devlink_try_get(struct devlink *devlink)
 	return NULL;
 }
 
+void devl_assert_locked(struct devlink *devlink)
+{
+	lockdep_assert_held(&devlink->lock);
+}
+EXPORT_SYMBOL_GPL(devl_assert_locked);
+
+#ifdef CONFIG_LOCKDEP
+/* For use in conjunction with LOCKDEP only e.g. rcu_dereference_protected() */
+bool devl_lock_is_held(struct devlink *devlink)
+{
+	return lockdep_is_held(&devlink->lock);
+}
+EXPORT_SYMBOL_GPL(devl_lock_is_held);
+#endif
+
+void devl_lock(struct devlink *devlink)
+{
+	mutex_lock(&devlink->lock);
+}
+EXPORT_SYMBOL_GPL(devl_lock);
+
+void devl_unlock(struct devlink *devlink)
+{
+	mutex_unlock(&devlink->lock);
+}
+EXPORT_SYMBOL_GPL(devl_unlock);
+
 static struct devlink *devlink_get_from_attrs(struct net *net,
 					      struct nlattr **attrs)
 {
@@ -9249,6 +9276,32 @@ static void devlink_port_type_warn_cancel(struct devlink_port *devlink_port)
 	cancel_delayed_work_sync(&devlink_port->type_warn_dw);
 }
 
+int devl_port_register(struct devlink *devlink,
+		       struct devlink_port *devlink_port,
+		       unsigned int port_index)
+{
+	lockdep_assert_held(&devlink->lock);
+
+	if (devlink_port_index_exists(devlink, port_index))
+		return -EEXIST;
+
+	WARN_ON(devlink_port->devlink);
+	devlink_port->devlink = devlink;
+	devlink_port->index = port_index;
+	spin_lock_init(&devlink_port->type_lock);
+	INIT_LIST_HEAD(&devlink_port->reporter_list);
+	mutex_init(&devlink_port->reporters_lock);
+	list_add_tail(&devlink_port->list, &devlink->port_list);
+	INIT_LIST_HEAD(&devlink_port->param_list);
+	INIT_LIST_HEAD(&devlink_port->region_list);
+
+	INIT_DELAYED_WORK(&devlink_port->type_warn_dw, &devlink_port_type_warn);
+	devlink_port_type_warn_schedule(devlink_port);
+	devlink_port_notify(devlink_port, DEVLINK_CMD_PORT_NEW);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(devl_port_register);
+
 /**
  *	devlink_port_register - Register devlink port
  *
@@ -9266,29 +9319,28 @@ int devlink_port_register(struct devlink *devlink,
 			  struct devlink_port *devlink_port,
 			  unsigned int port_index)
 {
-	mutex_lock(&devlink->lock);
-	if (devlink_port_index_exists(devlink, port_index)) {
-		mutex_unlock(&devlink->lock);
-		return -EEXIST;
-	}
+	int err;
 
-	WARN_ON(devlink_port->devlink);
-	devlink_port->devlink = devlink;
-	devlink_port->index = port_index;
-	spin_lock_init(&devlink_port->type_lock);
-	INIT_LIST_HEAD(&devlink_port->reporter_list);
-	mutex_init(&devlink_port->reporters_lock);
-	list_add_tail(&devlink_port->list, &devlink->port_list);
-	INIT_LIST_HEAD(&devlink_port->param_list);
-	INIT_LIST_HEAD(&devlink_port->region_list);
+	mutex_lock(&devlink->lock);
+	err = devl_port_register(devlink, devlink_port, port_index);
 	mutex_unlock(&devlink->lock);
-	INIT_DELAYED_WORK(&devlink_port->type_warn_dw, &devlink_port_type_warn);
-	devlink_port_type_warn_schedule(devlink_port);
-	devlink_port_notify(devlink_port, DEVLINK_CMD_PORT_NEW);
-	return 0;
+	return err;
 }
 EXPORT_SYMBOL_GPL(devlink_port_register);
 
+void devl_port_unregister(struct devlink_port *devlink_port)
+{
+	lockdep_assert_held(&devlink_port->devlink->lock);
+
+	devlink_port_type_warn_cancel(devlink_port);
+	devlink_port_notify(devlink_port, DEVLINK_CMD_PORT_DEL);
+	list_del(&devlink_port->list);
+	WARN_ON(!list_empty(&devlink_port->reporter_list));
+	WARN_ON(!list_empty(&devlink_port->region_list));
+	mutex_destroy(&devlink_port->reporters_lock);
+}
+EXPORT_SYMBOL_GPL(devl_port_unregister);
+
 /**
  *	devlink_port_unregister - Unregister devlink port
  *
@@ -9298,14 +9350,9 @@ void devlink_port_unregister(struct devlink_port *devlink_port)
 {
 	struct devlink *devlink = devlink_port->devlink;
 
-	devlink_port_type_warn_cancel(devlink_port);
-	devlink_port_notify(devlink_port, DEVLINK_CMD_PORT_DEL);
 	mutex_lock(&devlink->lock);
-	list_del(&devlink_port->list);
+	devl_port_unregister(devlink_port);
 	mutex_unlock(&devlink->lock);
-	WARN_ON(!list_empty(&devlink_port->reporter_list));
-	WARN_ON(!list_empty(&devlink_port->region_list));
-	mutex_destroy(&devlink_port->reporters_lock);
 }
 EXPORT_SYMBOL_GPL(devlink_port_unregister);