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>