rdma_accept(3) — Linux manual page

NAME | SYNOPSIS | ARGUMENTS | DESCRIPTION | RETURN VALUE | NOTES | CONNECTION PROPERTIES | INFINIBAND SPECIFIC | SEE ALSO | COLOPHON

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

NAME         top

       rdma_accept - Called to accept a connection request.

SYNOPSIS         top

       #include <rdma/rdma_cma.h>

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

ARGUMENTS         top

       id          Connection identifier associated with the request.

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

DESCRIPTION         top

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

RETURN VALUE         top

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

NOTES         top

       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         top

       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         top

       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         top

       rdma_listen(3), rdma_reject(3), rdma_get_cm_event(3)

COLOPHON         top

       This page is part of the rdma-core (RDMA Core Userspace Libraries
       and Daemons) project.  Information about the project can be found
       at ⟨https://github.com/linux-rdma/rdma-core⟩.  If you have a bug
       report for this manual page, send it to
       linux-rdma@vger.kernel.org.  This page was obtained from the
       project's upstream Git repository
       ⟨https://github.com/linux-rdma/rdma-core.git⟩ on 2021-08-27.  (At
       that time, the date of the most recent commit that was found in
       the repository was 2021-08-18.)  If you discover any rendering
       problems in this HTML version of the page, or you believe there
       is a better or more up-to-date source for the page, or you have
       corrections or improvements to the information in this COLOPHON
       (which is not part of the original manual page), send a mail to
       man-pages@man7.org

librdmacm                      2014-05-27                 RDMA_ACCEPT(3)

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