The mlx4 CM paravirtualization layer rewrites a VF's local
communication ID to a PF-visible ID when CM MADs are sent from the VF.
For messages that start or advance a connection from the VF side, such
as REQ, REP, MRA and SIDR_REQ, mlx4_ib_multiplex_cm_handler() allocates
an id_map_entry when no existing mapping is found.

A REJ is different because it is a terminal response to an already known
exchange. It should either find an existing id_map_entry, rewrite the
local communication ID, and schedule that entry for deletion, or it
should pass through unchanged when no mapping exists.

Some REJ messages, such as rejects for an inbound REQ before an MRA or
REP was sent, do not have an id_map_entry because their local_comm_id is
zero. Timeout REJ messages are handled in the initial lookup branch, but
a lookup miss there must not fall through to id_map_alloc(); such a miss
means there is no existing mapping to translate or delete for the REJ.

Commit 227a0e142e37 ("IB/mlx4: Add support for REJ due to timeout")
added the timeout REJ case to the initial branch so an outgoing timeout
REJ could reuse the id_map_entry that was created when the VF's REQ was
multiplexed. Reusing that entry is the useful part: it rewrites the
timeout REJ local_comm_id to the same PF-visible ID that was sent in the
REQ. If the lookup misses, allocating a new id_map_entry does not help
because the peer has never seen that new PF-visible ID, and REJ is not
starting a new exchange.

Keep timeout REJ handling in the initial lookup branch, but return before
allocation if no mapping is found. Handle the other REJ cases with the
same lookup-only behavior. When a mapping is found, translate the local
communication ID and schedule delayed deletion, as is already done for
DREQ and for received REJ in the demux path. When no mapping is found,
keep the existing pass-through behavior.

Signed-off-by: Praveen Kumar Kannoju <praveen.kannoju@oracle.com>
---
 drivers/infiniband/hw/mlx4/cm.c | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/drivers/infiniband/hw/mlx4/cm.c b/drivers/infiniband/hw/mlx4/cm.c
index 63a868a3822f..202fd5365e35 100644
--- a/drivers/infiniband/hw/mlx4/cm.c
+++ b/drivers/infiniband/hw/mlx4/cm.c
@@ -315,14 +315,20 @@ int mlx4_ib_multiplex_cm_handler(struct ib_device *ibdev, int port, int slave_id
 		id = id_map_get(ibdev, &pv_cm_id, slave_id, sl_cm_id);
 		if (id)
 			goto cont;
+		if (mad->mad_hdr.attr_id == CM_REJ_ATTR_ID)
+			return 0;
 		id = id_map_alloc(ibdev, slave_id, sl_cm_id);
 		if (IS_ERR(id)) {
 			mlx4_ib_warn(ibdev, "%s: id{slave: %d, sl_cm_id: 0x%x} Failed to id_map_alloc\n",
 				__func__, slave_id, sl_cm_id);
 			return PTR_ERR(id);
 		}
-	} else if (mad->mad_hdr.attr_id == CM_REJ_ATTR_ID ||
-		   mad->mad_hdr.attr_id == CM_SIDR_REP_ATTR_ID) {
+	} else if (mad->mad_hdr.attr_id == CM_REJ_ATTR_ID) {
+		sl_cm_id = get_local_comm_id(mad);
+		id = id_map_get(ibdev, &pv_cm_id, slave_id, sl_cm_id);
+		if (!id)
+			return 0;
+	} else if (mad->mad_hdr.attr_id == CM_SIDR_REP_ATTR_ID) {
 		return 0;
 	} else {
 		sl_cm_id = get_local_comm_id(mad);
@@ -338,7 +342,8 @@ int mlx4_ib_multiplex_cm_handler(struct ib_device *ibdev, int port, int slave_id
 cont:
 	set_local_comm_id(mad, id->pv_cm_id);
 
-	if (mad->mad_hdr.attr_id == CM_DREQ_ATTR_ID)
+	if (mad->mad_hdr.attr_id == CM_DREQ_ATTR_ID ||
+	    mad->mad_hdr.attr_id == CM_REJ_ATTR_ID)
 		schedule_delayed(ibdev, id);
 	return 0;
 }
-- 
2.43.7