Ensure no fork support with GDR. CUDA-aware code only.

This commit was SVN r29854.

ompi/mca/btl/openib/btl_openib_mca.c

@@ -793,6 +793,20 @@ int btl_openib_verify_mca_params (void)
     } else {
         mca_btl_openib_module.super.btl_flags &= ~MCA_BTL_FLAGS_CUDA_COPY_ASYNC_RECV;
     }
+    /* Cannot have fork support and GDR on at the same time.  If the user asks for both,
+     * then print a message and return error.  If the user does not explicitly ask for
+     * fork support, then turn it off in the presence of GDR.  */
+    if (mca_btl_openib_component.cuda_want_gdr && mca_btl_openib_component.cuda_have_gdr &&
+        mca_btl_openib_component.driver_have_gdr) {
+        if (1 == mca_btl_openib_component.want_fork_support) {
+              opal_show_help("help-mpi-btl-openib.txt", "no_fork_with_gdr",
+                             true, ompi_process_info.nodename);
+              return OMPI_ERR_BAD_PARAM;
+        }
+        if (-1 == mca_btl_openib_component.want_fork_support) {
+            mca_btl_openib_component.want_fork_support = 0;
+        }
+    }
 #endif
 
 #if BTL_OPENIB_MALLOC_HOOKS_ENABLED

ompi/mca/btl/openib/help-mpi-btl-openib.txt

@@ -723,3 +723,8 @@ installation does not have that support.  Contact Mellanox to figure
 out how to get an OFED stack with that support.
 
   Local host:              %s
+[no_fork_with_gdr]
+You cannot have fork support and CUDA GPU Direct RDMA support on at
+the same time.  Please disable one of them.
+
+  Local host:              %s