devlink: make sure driver does not read updated driverinit param before reload

The driverinit param purpose is to serve the driver during init/reload
time to provide a value, either default or set by user.

Make sure that driver does not read value updated by user before the
reload is performed. Hold the new value in a separate struct and switch
it during reload.

Note that this is required to be eventually possible to call
devl_param_driverinit_value_get() without holding instance lock.
Signed-off-by: Jiri Pirko <jiri@nvidia.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/devlink.h

@@ -489,6 +489,10 @@ struct devlink_param_item {
 	const struct devlink_param *param;
 	union devlink_param_value driverinit_value;
 	bool driverinit_value_valid;
+	union devlink_param_value driverinit_value_new; /* Not reachable
+							 * until reload.
+							 */
+	bool driverinit_value_new_valid;
 };
 
 enum devlink_param_generic_id {

net/devlink/dev.c

@@ -369,6 +369,9 @@ int devlink_reload(struct devlink *devlink, struct net *dest_net,
 	if (dest_net && !net_eq(dest_net, curr_net))
 		devlink_reload_netns_change(devlink, curr_net, dest_net);
 
+	if (action == DEVLINK_RELOAD_ACTION_DRIVER_REINIT)
+		devlink_params_driverinit_load_new(devlink);
+
 	err = devlink->ops->reload_up(devlink, action, limit, actions_performed, extack);
 	devlink_reload_failed_set(devlink, !!err);
 	if (err)

net/devlink/devl_internal.h

@@ -189,6 +189,9 @@ static inline bool devlink_reload_supported(const struct devlink_ops *ops)
 	return ops->reload_down && ops->reload_up;
 }
 
+/* Params */
+void devlink_params_driverinit_load_new(struct devlink *devlink);
+
 /* Resources */
 struct devlink_resource;
 int devlink_resources_validate(struct devlink *devlink,

net/devlink/leftover.c

@@ -4097,9 +4097,12 @@ static int devlink_nl_param_fill(struct sk_buff *msg, struct devlink *devlink,
 		if (!devlink_param_cmode_is_supported(param, i))
 			continue;
 		if (i == DEVLINK_PARAM_CMODE_DRIVERINIT) {
-			if (!param_item->driverinit_value_valid)
+			if (param_item->driverinit_value_new_valid)
+				param_value[i] = param_item->driverinit_value_new;
+			else if (param_item->driverinit_value_valid)
+				param_value[i] = param_item->driverinit_value;
+			else
 				return -EOPNOTSUPP;
-			param_value[i] = param_item->driverinit_value;
 		} else {
 			ctx.cmode = i;
 			err = devlink_param_get(devlink, param, &ctx);
@@ -4387,8 +4390,8 @@ static int __devlink_nl_cmd_param_set_doit(struct devlink *devlink,
 		return -EOPNOTSUPP;
 
 	if (cmode == DEVLINK_PARAM_CMODE_DRIVERINIT) {
-		param_item->driverinit_value = value;
-		param_item->driverinit_value_valid = true;
+		param_item->driverinit_value_new = value;
+		param_item->driverinit_value_new_valid = true;
 	} else {
 		if (!param->set)
 			return -EOPNOTSUPP;
@@ -9690,6 +9693,21 @@ void devl_param_driverinit_value_set(struct devlink *devlink, u32 param_id,
 }
 EXPORT_SYMBOL_GPL(devl_param_driverinit_value_set);
 
+void devlink_params_driverinit_load_new(struct devlink *devlink)
+{
+	struct devlink_param_item *param_item;
+
+	list_for_each_entry(param_item, &devlink->param_list, list) {
+		if (!devlink_param_cmode_is_supported(param_item->param,
+						      DEVLINK_PARAM_CMODE_DRIVERINIT) ||
+		    !param_item->driverinit_value_new_valid)
+			continue;
+		param_item->driverinit_value = param_item->driverinit_value_new;
+		param_item->driverinit_value_valid = true;
+		param_item->driverinit_value_new_valid = false;
+	}
+}
+
 /**
  *	devl_param_value_changed - notify devlink on a parameter's value
  *				   change. Should be called by the driver