[LU-6128] LNet: Problem handling error when lnet_check_routes() fail.

• Type: Bug
• Status: Resolved
• Priority: Critical
• Resolution: Fixed
• Fix Version/s: Lustre 2.7.0
• Labels: HB
• Severity: 3
• Assignee: Amir Shehata
• Reporter: Amir Shehata

Description

In LNetCtl():

                LNET_MUTEX_LOCK(&the_lnet.ln_api_mutex);
                rc = lnet_add_route(config->cfg_net,
                                    config->cfg_config_u.cfg_route.rtr_hop,
                                    config->cfg_nid,
                                    config->cfg_config_u.cfg_route.
                                        rtr_priority);
                LNET_MUTEX_UNLOCK(&the_lnet.ln_api_mutex);
                return (rc != 0) ? rc : lnet_check_routes();

If lnet_check_routes() returns error, it means the route just added was invalid and must be removed, see LNetNIInit(). It's wrong to just return the error to user space:
1. User space would treat the error as a failure to add the route, but the route was indeed added already.
2. Two conflicting routes now live in the routing table.