[PGPRO-5703] Place setting of n_peers after the exit on permission denied.

Previously setting of n_peers before error exit leds to a warning:
pg_query_state: last request was interrupted
and MAX_RCV_TIMEOUT pause at second function call.

Tags: pg_query_state

Author: antamel

pg_query_state.c

@@ -541,14 +541,18 @@ pg_query_state(PG_FUNCTION_ARGS)
 				break;
 			}
 		}
-		pg_atomic_write_u32(&counterpart_userid->n_peers, 1);
-		params->reqid = ++reqid;
-		pg_write_barrier();
 
 		counterpart_user_id = GetRemoteBackendUserId(proc);
 		if (!(superuser() || GetUserId() == counterpart_user_id))
+		{
+			UnlockShmem(&tag);
 			ereport(ERROR, (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
 							errmsg("permission denied")));
+		}
+
+		pg_atomic_write_u32(&counterpart_userid->n_peers, 1);
+		params->reqid = ++reqid;
+		pg_write_barrier();
 
 		bg_worker_procs = GetRemoteBackendWorkers(proc);