netdevsim: Forbid devlink reload when adding or deleting ports

In order to remove complexity in devlink core related to
devlink_reload_enable/disable, let's rewrite new_port/del_port
logic to rely on internal to netdevsim lcok.

We should protect only reload_down flow because it destroys nsim_dev,
which is needed for nsim_dev_port_add/nsim_dev_port_del to hold
port_list_lock.
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/netdevsim/bus.c

@@ -183,8 +183,6 @@ new_port_store(struct device *dev, struct device_attribute *attr,
 	       const char *buf, size_t count)
 {
 	struct nsim_bus_dev *nsim_bus_dev = to_nsim_bus_dev(dev);
-	struct nsim_dev *nsim_dev = dev_get_drvdata(dev);
-	struct devlink *devlink;
 	unsigned int port_index;
 	int ret;
 
@@ -195,12 +193,10 @@ new_port_store(struct device *dev, struct device_attribute *attr,
 	if (ret)
 		return ret;
 
-	devlink = priv_to_devlink(nsim_dev);
+	if (!mutex_trylock(&nsim_bus_dev->nsim_bus_reload_lock))
+		return -EBUSY;
 
-	mutex_lock(&nsim_bus_dev->nsim_bus_reload_lock);
-	devlink_reload_disable(devlink);
 	ret = nsim_dev_port_add(nsim_bus_dev, NSIM_DEV_PORT_TYPE_PF, port_index);
-	devlink_reload_enable(devlink);
 	mutex_unlock(&nsim_bus_dev->nsim_bus_reload_lock);
 	return ret ? ret : count;
 }
@@ -212,8 +208,6 @@ del_port_store(struct device *dev, struct device_attribute *attr,
 	       const char *buf, size_t count)
 {
 	struct nsim_bus_dev *nsim_bus_dev = to_nsim_bus_dev(dev);
-	struct nsim_dev *nsim_dev = dev_get_drvdata(dev);
-	struct devlink *devlink;
 	unsigned int port_index;
 	int ret;
 
@@ -224,12 +218,10 @@ del_port_store(struct device *dev, struct device_attribute *attr,
 	if (ret)
 		return ret;
 
-	devlink = priv_to_devlink(nsim_dev);
+	if (!mutex_trylock(&nsim_bus_dev->nsim_bus_reload_lock))
+		return -EBUSY;
 
-	mutex_lock(&nsim_bus_dev->nsim_bus_reload_lock);
-	devlink_reload_disable(devlink);
 	ret = nsim_dev_port_del(nsim_bus_dev, NSIM_DEV_PORT_TYPE_PF, port_index);
-	devlink_reload_enable(devlink);
 	mutex_unlock(&nsim_bus_dev->nsim_bus_reload_lock);
 	return ret ? ret : count;
 }

drivers/net/netdevsim/dev.c

@@ -864,16 +864,23 @@ static int nsim_dev_reload_down(struct devlink *devlink, bool netns_change,
 				struct netlink_ext_ack *extack)
 {
 	struct nsim_dev *nsim_dev = devlink_priv(devlink);
+	struct nsim_bus_dev *nsim_bus_dev;
+
+	nsim_bus_dev = nsim_dev->nsim_bus_dev;
+	if (!mutex_trylock(&nsim_bus_dev->nsim_bus_reload_lock))
+		return -EOPNOTSUPP;
 
 	if (nsim_dev->dont_allow_reload) {
 		/* For testing purposes, user set debugfs dont_allow_reload
 		 * value to true. So forbid it.
 		 */
 		NL_SET_ERR_MSG_MOD(extack, "User forbid the reload for testing purposes");
+		mutex_unlock(&nsim_bus_dev->nsim_bus_reload_lock);
 		return -EOPNOTSUPP;
 	}
 
 	nsim_dev_reload_destroy(nsim_dev);
+	mutex_unlock(&nsim_bus_dev->nsim_bus_reload_lock);
 	return 0;
 }