IB/core: clarify the documentation of ib_post_send()

index c179318..b5c894f 100644
@@ -1425,6 +1425,11 @@ int ib_destroy_qp(struct ib_qp *qp);
  * @send_wr: A list of work requests to post on the send queue.
  * @bad_send_wr: On an immediate failure, this parameter will reference
  *   the work request that failed to be posted on the QP.
+ *
+ * Note: while IBTA Vol1 section 11.4.1.1 specifies that if an immediate
+ * error is returned that the QP state shall not be affected, implementations
+ * of ib_post_send() may return an immediate error after already having
+ * processed one or more work requests.
  */
 static inline int ib_post_send(struct ib_qp *qp,
 			       struct ib_send_wr *send_wr,