devlink: add warning in case driver does not set port type

Prevent misbehavior of drivers who would not set port type for longer
period of time. Drivers should always set port type. Do WARN if that
happens.

Note that it is perfectly fine to temporarily not have the type set,
during initialization and port type change.
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/devlink.h

@@ -17,6 +17,7 @@
 #include <linux/list.h>
 #include <linux/netdevice.h>
 #include <linux/spinlock.h>
+#include <linux/workqueue.h>
 #include <net/net_namespace.h>
 #include <uapi/linux/devlink.h>
 
@@ -64,6 +65,7 @@ struct devlink_port {
 	enum devlink_port_type desired_type;
 	void *type_dev;
 	struct devlink_port_attrs attrs;
+	struct delayed_work type_warn_dw;
 };
 
 struct devlink_sb_pool_info {

net/core/devlink.c

@@ -21,6 +21,7 @@
 #include <linux/netdevice.h>
 #include <linux/spinlock.h>
 #include <linux/refcount.h>
+#include <linux/workqueue.h>
 #include <rdma/ib_verbs.h>
 #include <net/netlink.h>
 #include <net/genetlink.h>
@@ -5390,6 +5391,38 @@ void devlink_free(struct devlink *devlink)
 }
 EXPORT_SYMBOL_GPL(devlink_free);
 
+static void devlink_port_type_warn(struct work_struct *work)
+{
+	WARN(true, "Type was not set for devlink port.");
+}
+
+static bool devlink_port_type_should_warn(struct devlink_port *devlink_port)
+{
+	/* Ignore CPU and DSA flavours. */
+	return devlink_port->attrs.flavour != DEVLINK_PORT_FLAVOUR_CPU &&
+	       devlink_port->attrs.flavour != DEVLINK_PORT_FLAVOUR_DSA;
+}
+
+#define DEVLINK_PORT_TYPE_WARN_TIMEOUT (HZ * 30)
+
+static void devlink_port_type_warn_schedule(struct devlink_port *devlink_port)
+{
+	if (!devlink_port_type_should_warn(devlink_port))
+		return;
+	/* Schedule a work to WARN in case driver does not set port
+	 * type within timeout.
+	 */
+	schedule_delayed_work(&devlink_port->type_warn_dw,
+			      DEVLINK_PORT_TYPE_WARN_TIMEOUT);
+}
+
+static void devlink_port_type_warn_cancel(struct devlink_port *devlink_port)
+{
+	if (!devlink_port_type_should_warn(devlink_port))
+		return;
+	cancel_delayed_work_sync(&devlink_port->type_warn_dw);
+}
+
 /**
  *	devlink_port_register - Register devlink port
  *
@@ -5419,6 +5452,8 @@ int devlink_port_register(struct devlink *devlink,
 	list_add_tail(&devlink_port->list, &devlink->port_list);
 	INIT_LIST_HEAD(&devlink_port->param_list);
 	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;
 }
@@ -5433,6 +5468,7 @@ 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);
@@ -5446,6 +5482,7 @@ static void __devlink_port_type_set(struct devlink_port *devlink_port,
 {
 	if (WARN_ON(!devlink_port->registered))
 		return;
+	devlink_port_type_warn_cancel(devlink_port);
 	spin_lock(&devlink_port->type_lock);
 	devlink_port->type = type;
 	devlink_port->type_dev = type_dev;
@@ -5519,6 +5556,7 @@ EXPORT_SYMBOL_GPL(devlink_port_type_ib_set);
 void devlink_port_type_clear(struct devlink_port *devlink_port)
 {
 	__devlink_port_type_set(devlink_port, DEVLINK_PORT_TYPE_NOTSET, NULL);
+	devlink_port_type_warn_schedule(devlink_port);
 }
 EXPORT_SYMBOL_GPL(devlink_port_type_clear);