NAME

       ibv_post_srq_ops  -  perform  on  a  special  shared  receive  queue  (SRQ)  configuration
       manipulations

SYNOPSIS

       #include <infiniband/verbs.h>

       int ibv_post_srq_ops(struct ibv_srq *srq, struct ibv_ops_wr *wr,
                            struct ibv_ops_wr **bad_wr);

DESCRIPTION

       The ibv_post_srq_ops() performs series of offload configuration manipulations  on  special
       types  of  SRQ  srq.  Currenlty  it  is  used  to  configure  tag  matching SRQ. Series of
       configuration operations defined by linked lists of struct  ibv_ops_wr  elements  starting
       from wr.

       struct ibv_ops_wr {
               uint64_t                wr_id;   /* User defined WR ID */
               /* Pointer to next WR in list, NULL if last WR */
               struct ibv_ops_wr      *next;
               enum ibv_ops_wr_opcode  opcode;  /* From enum ibv_ops_wr_opcode */
               int                     flags;   /* From enum ibv_ops_flags */
               struct {
                       /* Number of unexpected messages
                        * handled by SW */
                       uint32_t unexpected_cnt;
                       /* Input parameter for the DEL opcode
                        * and output parameter for the ADD opcode */
                       uint32_t handle;
                       struct {
                               uint64_t                recv_wr_id;   /* User defined WR ID for TM_RECV */
                               struct ibv_sge         *sg_list; /* Pointer to the s/g array */
                               int                     num_sge; /* Size of the s/g array */
                               uint64_t                tag;
                               uint64_t                mask;    /* Incoming message considered matching if
                                                                   TMH.tag & entry.mask == entry.tag */
                       } add;
               } tm;
       };

       First  part  of struct ibv_ops_wr retains ibv_send_wr notion.  Opcode defines operation to
       perform. Currently supported IBV_WR_TAG_ADD, IBV_WR_TAG_DEL  and  IBV_WR_TAG_SYNC  values.
       See below for detailed description.

       To  allow  reliable  data  delivery  TM  SRQ  maintains  special low level synchronization
       primitive - phase synchronization. Receive side message handling comprises two  concurrent
       activities  -  posting  tagged  buffers  by SW and receiving incoming messages by HW. This
       process considered coherent only if all unexpected messages received by HW  is  completely
       processed   in   SW.   To  pass  to  hardware  number  of  processed  unexpected  messages
       unexpected_cnt field should be used and IBV_OPS_TM_SYNC flag should be set.

       To request WC for tag list operations IBV_OPS_SIGNALED flags should  be  passed.  In  this
       case WC will be generated on TM SRQ's CQ, provided wr_id will identify WC.

       Opcode  IBV_WR_TAG_ADD  used to add tag entry to tag matching list.  Tag entry consists of
       SGE list, tag & mask (matching  parameters),  user  specified  opaque  wr_id  (passed  via
       recv_wr_id  field)  and  uniquely  identified by handle (returned by driver).  Size of tag
       matching list is limited by max_num_tags.  SGE list size is limited by max_sge.

       Opcode IBV_WR_TAG_DEL removes previously added tag entry.  Field handle should be  set  to
       value  returned  by previously performed IBV_WR_TAG_ADD operation.  Operation may fail due
       to concurrent tag consumption - in this case IBV_WC_TM_ERR status will be returned in WC.

       Opcode IBV_WR_TAG_SYNC may be used if no  changes  to  matching  list  required,  just  to
       updated unexpected messages counter.

       IBV_WC_TM_SYNC_REQ  flag  returned in list operation WC shows that counter synchronization
       required.  This  flag  also  may  be  returned  by  unexpected  receive  WC,  asking   for
       IBV_WR_TAG_SYNC operation to keep TM coherence consistency.

RETURN VALUE

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

SEE ALSO

       ibv_create_srq_ex(3),

AUTHORS

       Artemy Kovalyov <artemyko@mellanox.com>