IB/core: Add support for multicast loopback blocking

This patch also adds a creation flag for QPs,
IB_QP_CREATE_MULTICAST_BLOCK_LOOPBACK, which when set means that
multicast sends from the QP to a group that the QP is attached to will
not be looped back to the QP's receive queue.  This can be used to
save receive resources when a consumer does not want a local copy of
multicast traffic; for example IPoIB must waste CPU time throwing away
such local copies of multicast traffic.

This patch also adds a device capability flag that shows whether a
device supports this feature or not.

Signed-off-by: Ron Livne <ronli@voltaire.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

1 files changed, 3 insertions, 1 deletions

diff --git a/include/rdma/ib_verbs.h b/include/rdma/ib_verbs.h
index 10ebaaae0161..07b41e05565a 100644
--- a/include/rdma/ib_verbs.h
+++ b/include/rdma/ib_verbs.h
@@ -104,6 +104,7 @@ enum ib_device_cap_flags {
         IB_DEVICE_UD_IP_CSUM            = (1<<18),
         IB_DEVICE_UD_TSO                = (1<<19),
         IB_DEVICE_MEM_MGT_EXTENSIONS    = (1<<21),
+        IB_DEVICE_BLOCK_MULTICAST_LOOPBACK = (1<<22),
 };
 
 enum ib_atomic_cap {
@@ -555,7 +556,8 @@ enum ib_qp_type {
 };
 
 enum ib_qp_create_flags {
-        IB_QP_CREATE_IPOIB_UD_LSO       = 1 << 0,
+        IB_QP_CREATE_IPOIB_UD_LSO               = 1 << 0,
+        IB_QP_CREATE_BLOCK_MULTICAST_LOOPBACK   = 1 << 1,
 };
 
 struct ib_qp_init_attr {