pml_ucx: initialize req_mpi_object.comm for error handler

without this fix, an error handler invoked on pml_ucx request would
segfault while trying to dereference requests[i]->req_mpi_object.comm

Signed-off-by: Yossi Itigin <yosefe@mellanox.com>

ompi/mca/pml/ucx/pml_ucx.c

@@ -477,11 +477,12 @@ int mca_pml_ucx_irecv_init(void *buf, size_t count, ompi_datatype_t *datatype,
     PML_UCX_TRACE_RECV("irecv_init request *%p=%p", buf, count, datatype, src,
                        tag, comm, (void*)request, (void*)req);
 
-    req->ompi.req_state = OMPI_REQUEST_INACTIVE;
-    req->flags          = 0;
-    req->buffer         = buf;
-    req->count          = count;
-    req->datatype.datatype = mca_pml_ucx_get_datatype(datatype);
+    req->ompi.req_state           = OMPI_REQUEST_INACTIVE;
+    req->ompi.req_mpi_object.comm = comm;
+    req->flags                    = 0;
+    req->buffer                   = buf;
+    req->count                    = count;
+    req->datatype.datatype        = mca_pml_ucx_get_datatype(datatype);
 
     PML_UCX_MAKE_RECV_TAG(req->tag, req->recv.tag_mask, tag, src, comm);
 
@@ -510,7 +511,8 @@ int mca_pml_ucx_irecv(void *buf, size_t count, ompi_datatype_t *datatype,
     }
 
     PML_UCX_VERBOSE(8, "got request %p", (void*)req);
-    *request = req;
+    req->req_mpi_object.comm = comm;
+    *request                 = req;
     return OMPI_SUCCESS;
 }
 
@@ -582,13 +584,15 @@ int mca_pml_ucx_isend_init(const void *buf, size_t count, ompi_datatype_t *datat
         return OMPI_ERROR;
     }
 
-    req->ompi.req_state = OMPI_REQUEST_INACTIVE;
-    req->flags          = MCA_PML_UCX_REQUEST_FLAG_SEND;
-    req->buffer         = (void *)buf;
-    req->count          = count;
-    req->tag            = PML_UCX_MAKE_SEND_TAG(tag, comm);
-    req->send.mode      = mode;
-    req->send.ep        = ep;
+    req->ompi.req_state           = OMPI_REQUEST_INACTIVE;
+    req->ompi.req_mpi_object.comm = comm;
+    req->flags                    = MCA_PML_UCX_REQUEST_FLAG_SEND;
+    req->buffer                   = (void *)buf;
+    req->count                    = count;
+    req->tag                      = PML_UCX_MAKE_SEND_TAG(tag, comm);
+    req->send.mode                = mode;
+    req->send.ep                  = ep;
+
     if (MCA_PML_BASE_SEND_BUFFERED == mode) {
         req->datatype.ompi_datatype = datatype;
         OBJ_RETAIN(datatype);
@@ -706,7 +710,8 @@ int mca_pml_ucx_isend(const void *buf, size_t count, ompi_datatype_t *datatype,
         return OMPI_SUCCESS;
     } else if (!UCS_PTR_IS_ERR(req)) {
         PML_UCX_VERBOSE(8, "got request %p", (void*)req);
-        *request = req;
+        req->req_mpi_object.comm = comm;
+        *request                 = req;
         return OMPI_SUCCESS;
     } else {
         PML_UCX_ERROR("ucx send failed: %s", ucs_status_string(UCS_PTR_STATUS(req)));
@@ -786,7 +791,7 @@ int mca_pml_ucx_send(const void *buf, size_t count, ompi_datatype_t *datatype, i
 }
 
 int mca_pml_ucx_iprobe(int src, int tag, struct ompi_communicator_t* comm,
-                         int *matched, ompi_status_public_t* mpi_status)
+                       int *matched, ompi_status_public_t* mpi_status)
 {
     static unsigned progress_count = 0;
 
@@ -811,7 +816,7 @@ int mca_pml_ucx_iprobe(int src, int tag, struct ompi_communicator_t* comm,
 }
 
 int mca_pml_ucx_probe(int src, int tag, struct ompi_communicator_t* comm,
-                        ompi_status_public_t* mpi_status)
+                      ompi_status_public_t* mpi_status)
 {
     ucp_tag_t ucp_tag, ucp_tag_mask;
     ucp_tag_recv_info_t info;

ompi/mca/pml/ucx/pml_ucx_request.c

@@ -228,7 +228,7 @@ void mca_pml_ucx_completed_request_init(ompi_request_t *ompi_req)
     mca_pml_ucx_request_init_common(ompi_req, false, OMPI_REQUEST_ACTIVE,
                                     mca_pml_completed_request_free,
                                     mca_pml_completed_request_cancel);
+    ompi_req->req_mpi_object.comm = &ompi_mpi_comm_world.comm;
     ompi_request_complete(ompi_req, false);
-
 }