--- rpc/svc.c	2015-11-17 23:49:36.363172000 -0500
+++ rpc/svc.c	2015-11-18 15:45:26.310954000 -0500
@@ -1232,9 +1232,11 @@ svc_run_internal(SVCGROUP *grp, bool_t i
 					if (stpref != st)
 						rqstp = NULL;
 				} else {
+					mtx_lock(&st->st_lock);
 					rqstp->rq_thread = st;
 					STAILQ_INSERT_TAIL(&st->st_reqs,
 					    rqstp, rq_link);
+					mtx_unlock(&st->st_lock);
 				}
 			}
 		} while (rqstp == NULL && stat == XPRT_MOREREQS