1RDMA_GET_CM_EVENT(3) Librdmacm Programmer's Manual RDMA_GET_CM_EVENT(3)
2
6 rdma_get_cm_event - Retrieves the next pending communication event.
7
9 #include <rdma/rdma_cma.h>
10 int rdma_get_cm_event (struct rdma_event_channel *channel, struct
12 rdma_cm_event **event);
13
15 channel Event channel to check for events.
16 event Allocated information about the next communication event.
18
20 Retrieves a communication event. If no events are pending, by default,
21 the call will block until an event is received.
22
24 Returns 0 on success, or -1 on error. If an error occurs, errno will
25 be set to indicate the failure reason.
26
28 The default synchronous behavior of this routine can be changed by mod‐
29 ifying the file descriptor associated with the given channel. All
30 events that are reported must be acknowledged by calling
31 rdma_ack_cm_event. Destruction of an rdma_cm_id will block until
32 related events have been acknowledged.
33
35 Communication event details are returned in the rdma_cm_event struc‐
36 ture. This structure is allocated by the rdma_cm and released by the
37 rdma_ack_cm_event routine. Details of the rdma_cm_event structure are
38 given below.
39 id The rdma_cm identifier associated with the event. If the
41 event type is RDMA_CM_EVENT_CONNECT_REQUEST, then this ref‐
42 erences a new id for that communication.
43 listen_id For RDMA_CM_EVENT_CONNECT_REQUEST event types, this refer‐
45 ences the corresponding listening request identifier.
46 event Specifies the type of communication event which occurred.
48 See EVENT TYPES below.
49 status Returns any asynchronous error information associated with
51 an event. The status is zero if the operation was success‐
52 ful, otherwise the status value is non-zero and is either
53 set to an errno or a transport specific value. For details
54 on transport specific status values, see the event type
55 information below.
56 param Provides additional details based on the type of event.
58 Users should select the conn or ud subfields based on the
59 rdma_port_space of the rdma_cm_id associated with the
60 event. See UD EVENT DATA and CONN EVENT DATA below.
61
63 Event parameters related to unreliable datagram (UD) services:
64 RDMA_PS_UDP and RDMA_PS_IPOIB. The UD event data is valid for
65 RDMA_CM_EVENT_ESTABLISHED and RDMA_CM_EVENT_MULTICAST_JOIN events,
66 unless stated otherwise.
67 private_data
69 References any user-specified data associated with
70 RDMA_CM_EVENT_CONNECT_REQUEST or RDMA_CM_EVENT_ESTABLISHED
71 events. The data referenced by this field matches that
72 specified by the remote side when calling rdma_connect or
73 rdma_accept. This field is NULL if the event does not
74 include private data. The buffer referenced by this
75 pointer is deallocated when calling rdma_ack_cm_event.
76 private_data_len
78 The size of the private data buffer. Users should note
79 that the size of the private data buffer may be larger than
80 the amount of private data sent by the remote side. Any
81 additional space in the buffer will be zeroed out.
82 ah_attr Address information needed to send data to the remote end‐
84 point(s). Users should use this structure when allocating
85 their address handle.
86 qp_num QP number of the remote endpoint or multicast group.
88 qkey QKey needed to send data to the remote endpoint(s).
90
92 Event parameters related to connected QP services: RDMA_PS_TCP. The
93 connection related event data is valid for RDMA_CM_EVENT_CON‐
94 NECT_REQUEST and RDMA_CM_EVENT_ESTABLISHED events, unless stated other‐
95 wise.
96 private_data
98 References any user-specified data associated with the
99 event. The data referenced by this field matches that
100 specified by the remote side when calling rdma_connect or
101 rdma_accept. This field is NULL if the event does not
102 include private data. The buffer referenced by this
103 pointer is deallocated when calling rdma_ack_cm_event.
104 private_data_len
106 The size of the private data buffer. Users should note
107 that the size of the private data buffer may be larger than
108 the amount of private data sent by the remote side. Any
109 additional space in the buffer will be zeroed out.
110 responder_resources
112 The number of responder resources requested of the recipi‐
113 ent. This field matches the initiator depth specified by
114 the remote node when calling rdma_connect and rdma_accept.
115 initiator_depth
117 The maximum number of outstanding RDMA read/atomic opera‐
118 tions that the recipient may have outstanding. This field
119 matches the responder resources specified by the remote
120 node when calling rdma_connect and rdma_accept.
121 flow_control
123 Indicates if hardware level flow control is provided by the
124 sender.
125 retry_count For RDMA_CM_EVENT_CONNECT_REQUEST events only, indicates
127 the number of times that the recipient should retry send
128 operations.
129 rnr_retry_count
131 The number of times that the recipient should retry
132 receiver not ready (RNR) NACK errors.
133 srq Specifies if the sender is using a shared-receive queue.
135 qp_num Indicates the remote QP number for the connection.
137
139 The following types of communication events may be reported.
140 RDMA_CM_EVENT_ADDR_RESOLVED
142 Address resolution (rdma_resolve_addr) completed successfully.
143 RDMA_CM_EVENT_ADDR_ERROR
145 Address resolution (rdma_resolve_addr) failed.
146 RDMA_CM_EVENT_ROUTE_RESOLVED
148 Route resolution (rdma_resolve_route) completed successfully.
149 RDMA_CM_EVENT_ROUTE_ERROR
151 Route resolution (rdma_resolve_route) failed.
152 RDMA_CM_EVENT_CONNECT_REQUEST
154 Generated on the passive side to notify the user of a new con‐
155 nection request.
156 RDMA_CM_EVENT_CONNECT_RESPONSE
158 Generated on the active side to notify the user of a successful
159 response to a connection request. It is only generated on
160 rdma_cm_id's that do not have a QP associated with them.
161 RDMA_CM_EVENT_CONNECT_ERROR
163 Indicates that an error has occurred trying to establish or a
164 connection. May be generated on the active or passive side of a
165 connection.
166 RDMA_CM_EVENT_UNREACHABLE
168 Generated on the active side to notify the user that the remote
169 server is not reachable or unable to respond to a connection
170 request. If this event is generated in response to a UD QP res‐
171 olution request over InfiniBand, the event status field will
172 contain an errno, if negative, or the status result carried in
173 the IB CM SIDR REP message.
174 RDMA_CM_EVENT_REJECTED
176 Indicates that a connection request or response was rejected by
177 the remote end point. The event status field will contain the
178 transport specific reject reason if available. Under Infini‐
179 Band, this is the reject reason carried in the IB CM REJ mes‐
180 sage.
181 RDMA_CM_EVENT_ESTABLISHED
183 Indicates that a connection has been established with the remote
184 end point.
185 RDMA_CM_EVENT_DISCONNECTED
187 The connection has been disconnected.
188 RDMA_CM_EVENT_DEVICE_REMOVAL
190 The local RDMA device associated with the rdma_cm_id has been
191 removed. Upon receiving this event, the user must destroy the
192 related rdma_cm_id.
193 RDMA_CM_EVENT_MULTICAST_JOIN
195 The multicast join operation (rdma_join_multicast) completed
196 successfully.
197 RDMA_CM_EVENT_MULTICAST_ERROR
199 An error either occurred joining a multicast group, or, if the
200 group had already been joined, on an existing group. The speci‐
201 fied multicast group is no longer accessible and should be
202 rejoined, if desired.
203 RDMA_CM_EVENT_ADDR_CHANGE
205 The network device associated with this ID through address reso‐
206 lution changed its HW address, eg following of bonding failover.
207 This event can serve as a hint for applications who want the
208 links used for their RDMA sessions to align with the network
209 stack.
210 RDMA_CM_EVENT_TIMEWAIT_EXIT
212 The QP associated with a connection has exited its timewait
213 state and is now ready to be re-used. After a QP has been dis‐
214 connected, it is maintained in a timewait state to allow any in
215 flight packets to exit the network. After the timewait state
216 has completed, the rdma_cm will report this event.
217
219 rdma_ack_cm_event(3), rdma_create_event_channel(3),
220 rdma_resolve_addr(3), rdma_resolve_route(3), rdma_connect(3), rdma_lis‐
221 ten(3), rdma_join_multicast(3), rdma_destroy_id(3), rdma_event_str(3)
222librdmacm 2007-10-31 RDMA_GET_CM_EVENT(3)