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NAME

       ibv_post_send - post a list of work requests (WRs) to a send queue

SYNOPSIS

       #include <infiniband/verbs.h>

       int ibv_post_send(struct ibv_qp *qp, struct ibv_send_wr *wr,
                         struct ibv_send_wr **bad_wr);

DESCRIPTION

       ibv_post_send()  posts  the linked list of work requests (WRs) starting
       with wr to the send queue of the queue pair qp.   It  stops  processing
       WRs  from  this  list  at  the  first  failure  (that  can  be detected
       immediately while requests are being posted), and returns this  failing
       WR through bad_wr.

       The   argument   wr   is   an   ibv_send_wr   struct,   as  defined  in
       <infiniband/verbs.h>.

       struct ibv_send_wr {
               uint64_t                wr_id;                  /* User defined WR ID */
               struct ibv_send_wr     *next;                   /* Pointer to next WR in list, NULL if last WR */
               struct ibv_sge         *sg_list;                /* Pointer to the s/g array */
               int                     num_sge;                /* Size of the s/g array */
               enum ibv_wr_opcode      opcode;                 /* Operation type */
               int                     send_flags;             /* Flags of the WR properties */
               uint32_t                imm_data;               /* Immediate data (in network byte order) */
               union {
                       struct {
                               uint64_t        remote_addr;    /* Start address of remote memory buffer */
                               uint32_t        rkey;           /* Key of the remote Memory Region */
                       } rdma;
                       struct {
                               uint64_t        remote_addr;    /* Start address of remote memory buffer */
                               uint64_t        compare_add;    /* Compare operand */
                               uint64_t        swap;           /* Swap operand */
                               uint32_t        rkey;           /* Key of the remote Memory Region */
                       } atomic;
                       struct {
                               struct ibv_ah  *ah;             /* Address handle (AH) for the remote node address */
                               uint32_t        remote_qpn;     /* QP number of the destination QP */
                               uint32_t        remote_qkey;    /* Q_Key number of the destination QP */
                       } ud;
               } wr;
       };

       struct ibv_sge {
               uint64_t                addr;                   /* Start address of the local memory buffer */
               uint32_t                length;                 /* Length of the buffer */
               uint32_t                lkey;                   /* Key of the local Memory Region */
       };

       Each QP Transport Service Type supports a specific set of  opcodes,  as
       shown in the following table:

       OPCODE                      | IBV_QPT_UD | IBV_QPT_UC | IBV_QPT_RC
       ----------------------------+------------+------------+-----------
       IBV_WR_SEND                 |     X      |     X      |     X
       IBV_WR_SEND_WITH_IMM        |     X      |     X      |     X
       IBV_WR_RDMA_WRITE           |            |     X      |     X
       IBV_WR_RDMA_WRITE_WITH_IMM  |            |     X      |     X
       IBV_WR_RDMA_READ            |            |            |     X
       IBV_WR_ATOMIC_CMP_AND_SWP   |            |            |     X
       IBV_WR_ATOMIC_FETCH_AND_ADD |            |            |     X

       The  attribute  send_flags  describes  the  properties of the WR. It is
       either 0 or the bitwise OR of one or more of the following flags:

       IBV_SEND_FENCE  Set the  fence  indicator.  Valid  only  for  QPs  with
       Transport Service Type IBV_QPT_RC

       IBV_SEND_SIGNALED  Set the completion notification indicator.  Relevant
       only if QP was created with sq_sig_all=0

       IBV_SEND_SOLICITED  Set the solicited event indicator. Valid  only  for
       Send and RDMA Write with immediate

       IBV_SEND_INLINE  Send data in given gather list as inline data
              in a send WQE.  Valid only for Send and RDMA Write.   The  L_Key
              will not be checked.

RETURN VALUE

       ibv_post_send()  returns 0 on success, or the value of errno on failure
       (which indicates the failure reason).

NOTES

       The user should not alter or destroy  AHs  associated  with  WRs  until
       request is fully executed and a work completion has been retrieved from
       the corresponding completion queue (CQ) to avoid unexpected behavior.

       The buffers used by a WR can only be safely reused after WR the request
       is  fully  executed  and  a work completion has been retrieved from the
       corresponding completion queue (CQ). However,  if  the  IBV_SEND_INLINE
       flag  was  set,  the  buffer  can  be reused immediately after the call
       returns.

SEE ALSO

       ibv_create_qp(3),          ibv_create_ah(3),          ibv_post_recv(3),
       ibv_post_srq_recv(3), ibv_poll_cq(3)

AUTHORS

       Dotan Barak <dotanba@gmail.com>