rdma_cm: add rdma_consumer_reject_data helper function

rdma_consumer_reject_data() will return the private data pointer
and length if any is available.

Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>
diff --git a/drivers/infiniband/core/cma.c b/drivers/infiniband/core/cma.c
index bd1d4fe..8c30e3d 100644
--- a/drivers/infiniband/core/cma.c
+++ b/drivers/infiniband/core/cma.c
@@ -128,6 +128,22 @@ bool rdma_is_consumer_reject(struct rdma_cm_id *id, int reason)
 }
 EXPORT_SYMBOL(rdma_is_consumer_reject);
 
+const void *rdma_consumer_reject_data(struct rdma_cm_id *id,
+				      struct rdma_cm_event *ev, u8 *data_len)
+{
+	const void *p;
+
+	if (rdma_is_consumer_reject(id, ev->status)) {
+		*data_len = ev->param.conn.private_data_len;
+		p = ev->param.conn.private_data;
+	} else {
+		*data_len = 0;
+		p = NULL;
+	}
+	return p;
+}
+EXPORT_SYMBOL(rdma_consumer_reject_data);
+
 static void cma_add_one(struct ib_device *device);
 static void cma_remove_one(struct ib_device *device, void *client_data);