RDMA/ucma: Add option to manually set IB path

Export rdma_set_ib_paths to user space to allow applications to
manually set the IB path used for connections.  This allows
alternative ways for a user space application or library to obtain
path record information, including retrieving path information
from cached data, avoiding direct interaction with the IB SA.
The IB SA is a single, centralized entity that can limit scaling
on large clusters running MPI applications.

Future changes to the rdma cm can expand on this framework to
support the full range of features allowed by the IB CM, such as
separate forward and reverse paths and APM.

Signed-off-by: Sean Hefty <sean.hefty@intel.com>
Reviewed-By: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

1 files changed, 4 insertions, 2 deletions

diff --git a/include/rdma/rdma_user_cm.h b/include/rdma/rdma_user_cm.h
index c55705460b87..1d165022c02d 100644
--- a/include/rdma/rdma_user_cm.h
+++ b/include/rdma/rdma_user_cm.h
@@ -215,12 +215,14 @@ struct rdma_ucm_event_resp {
 
 /* Option levels */
 enum {
-        RDMA_OPTION_ID          = 0
+        RDMA_OPTION_ID          = 0,
+        RDMA_OPTION_IB          = 1
 };
 
 /* Option details */
 enum {
-        RDMA_OPTION_ID_TOS      = 0
+        RDMA_OPTION_ID_TOS      = 0,
+        RDMA_OPTION_IB_PATH     = 1
 };
 
 struct rdma_ucm_set_option {