RDMACMEVENTDISCONNECTED

RDMACMEVENTDISCONNECTED is an event type associated with the RDMA Connection Manager (RDMA-CM) API used by applications that establish connections over RDMA-capable transports such as InfiniBand and RoCE. It denotes that the connection linked to a previously established RDMA CM identifier (cm_id) has been disconnected.

The event can occur for several reasons, including a voluntary disconnect initiated by either side, an error condition on the underlying transport, or a failure of the remote peer. When a disconnect happens, the RDMA-CM layer emits the RDMACMEVENTDISCONNECTED event to the application’s event channel. This event informs the application that the associated connection is no longer usable and that resources tied to that connection should be cleaned up.

In typical usage, applications retrieve RDMA-CM events from an event channel, check for the event type, and respond accordingly. When handling a RDMACMEVENTDISCONNECTED event, the application should acknowledge the event with rdma_ack_cm_event, then perform necessary cleanup such as closing queue pairs, deregistering memory regions, destroying protection domains, and releasing the cm_id. After a disconnect, the same cm_id is generally not reused, and a new connection establishment process may be started if desired.

Notes for developers include that the exact field names and handling APIs may vary between kernel and user-space libraries or across API versions. Always refer to the specific RDMA-CM documentation for the environment in which the application runs. Related RDMA-CM events include RDMA_CM_EVENT_ESTABLISHED and RDMA_CM_EVENT_CONNECT_REQUEST.