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 <[e-mail]>
Reviewed-by: Christoph Hellwig <[e-mail]>
Signed-off-by: Steve Wise <[e-mail]>
Signed-off-by: Doug Ledford <[e-mail]>

drivers/infiniband/core/cma.c

···
 }
 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);
 

include/rdma/rdma_cm.h

···
  */
 bool rdma_is_consumer_reject(struct rdma_cm_id *id, int reason);
 
+/**
+ * rdma_consumer_reject_data - return the consumer reject private data and
+ *			       length, if any.
+ * @id: Communication identifier that received the REJECT event.
+ * @ev: RDMA CM reject event.
+ * @data_len: Pointer to the resulting length of the consumer data.
+ */
+const void *rdma_consumer_reject_data(struct rdma_cm_id *id,
+				      struct rdma_cm_event *ev, u8 *data_len);
+
 #endif /* RDMA_CM_H */