RDMA_ACCEPT(3)           Librdmacm Programmer's Manual          RDMA_ACCEPT(3)

NAME
       rdma_accept - Called to accept a connection request.

SYNOPSIS
       #include <rdma/rdma_cma.h>

       int rdma_accept (struct rdma_cm_id *id, struct rdma_conn_param
       *conn_param);

ARGUMENTS
       id          Connection identifier associated with the request.

       conn_param  Information needed to establish the connection.  See
                   CONNECTION PROPERTIES below for details.

DESCRIPTION
       Called from the listening side to accept a connection or datagram
       service lookup request.

RETURN VALUE
       Returns 0 on success, or -1 on error.  If an error occurs, errno will
       be set to indicate the failure reason.

NOTES
       Unlike the socket accept routine, rdma_accept is not called on a
       listening rdma_cm_id.  Instead, after calling rdma_listen, the user
       waits for an RDMA_CM_EVENT_CONNECT_REQUEST event to occur.  Connection
       request events give the user a newly created rdma_cm_id, similar to a
       new socket, but the rdma_cm_id is bound to a specific RDMA device.
       rdma_accept is called on the new rdma_cm_id.

CONNECTION PROPERTIES
       The following properties are used to configure the communication and
       specified by the conn_param parameter when accepting a connection or
       datagram communication request.  Users should use the rdma_conn_param
       values reported in the connection request event to determine
       appropriate values for these fields when accepting.  Users may
       reference the rdma_conn_param structure in the connection event
       directly, or can reference their own structure.  If the rdma_conn_param
       structure from an event is referenced, the event must not be acked
       until after this call returns.

       If the conn_param parameter is NULL, the values reported in the
       connection request event are used, adjusted down based on local
       hardware restrictions.

       private_data
              References a user-controlled data buffer.  The contents of the
              buffer are copied and transparently passed to the remote side as
              part of the communication request.  May be NULL if private_data
              is not required.

       private_data_len
              Specifies the size of the user-controlled data buffer.  Note
              that the actual amount of data transferred to the remote side is
              transport dependent and may be larger than that requested.

       responder_resources
              The maximum number of outstanding RDMA read and atomic
              operations that the local side will accept from the remote side.
              Applies only to RDMA_PS_TCP.  This value must be less than or
              equal to the local RDMA device attribute max_qp_rd_atom, but
              preferably greater than or equal to the responder_resources
              value reported in the connect request event.

       initiator_depth
              The maximum number of outstanding RDMA read and atomic
              operations that the local side will have to the remote side.
              Applies only to RDMA_PS_TCP.  This value must be less than or
              equal to the local RDMA device attribute max_qp_init_rd_atom and
              the initiator_depth value reported in the connect request event.

       flow_control
              Specifies if hardware flow control is available.  This value is
              exchanged with the remote peer and is not used to configure the
              QP.  Applies only to RDMA_PS_TCP.

       retry_count
              This value is ignored.

       rnr_retry_count
              The maximum number of times that a send operation from the
              remote peer should be retried on a connection after receiving a
              receiver not ready (RNR) error.  RNR errors are generated when a
              send request arrives before a buffer has been posted to receive
              the incoming data.  Applies only to RDMA_PS_TCP.

       srq    Specifies if the QP associated with the connection is using a
              shared receive queue.  This field is ignored by the library if a
              QP has been created on the rdma_cm_id.  Applies only to
              RDMA_PS_TCP.

       qp_num Specifies the QP number associated with the connection.  This
              field is ignored by the library if a QP has been created on the
              rdma_cm_id.

INFINIBAND SPECIFIC
       In addition to the connection properties defined above, InfiniBand QPs
       are configured with minimum RNR NAK timer and local ACK timeout values.
       The minimum RNR NAK timer value is set to 0, for a delay of 655 ms.
       The local ACK timeout is calculated based on the packet lifetime and
       local HCA ACK delay.  The packet lifetime is determined by the
       InfiniBand Subnet Administrator and is part of the route (path record)
       information obtained by the active side of the connection.  The HCA ACK
       delay is a property of the locally used HCA.

       The RNR retry count is a 3-bit value.

       The length of the private data provided by the user is limited to 196
       bytes for RDMA_PS_TCP, or 136 bytes for RDMA_PS_UDP.

SEE ALSO
       rdma_listen(3), rdma_reject(3), rdma_get_cm_event(3)

librdmacm                         2014-05-27                    RDMA_ACCEPT(3)