From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755510AbYKTOcS (ORCPT ); Thu, 20 Nov 2008 09:32:18 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754791AbYKTOcH (ORCPT ); Thu, 20 Nov 2008 09:32:07 -0500 Received: from earthlight.etchedpixels.co.uk ([81.2.110.250]:56225 "EHLO lxorguk.ukuu.org.uk" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1754758AbYKTOcG (ORCPT ); Thu, 20 Nov 2008 09:32:06 -0500 Date: Thu, 20 Nov 2008 14:31:47 +0000 From: Alan Cox To: Thomas Pfaff Cc: linux-kernel@vger.kernel.org Subject: Re: Question about TTY_DO_WRITE_WAKEUP Message-ID: <20081120143147.5e8d6c20@lxorguk.ukuu.org.uk> In-Reply-To: References: <20081120131726.2636b559@lxorguk.ukuu.org.uk> X-Mailer: Claws Mail 3.5.0 (GTK+ 2.12.12; x86_64-redhat-linux-gnu) Organization: Red Hat UK Cyf., Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SL4 1TE, Y Deyrnas Gyfunol. Cofrestrwyd yng Nghymru a Lloegr o'r rhif cofrestru 3798903 Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > Is the TTY_DO_WRITE_WAKEUP bit some kind of cruft that can be removed entirely > or should i generate a patch for serial devices only ? It shouldn't happen at the serial level. The line discipline sets the flag as and when it has data for the process above. The expected flow in normal use is app writes to tty data goes to n_tty ldisc goes to tty n_tty ldisc seems tty blocked n_tty ldisc sets DO_WRITE_WAKEUP tty gets ucongested calls n_tty write_wakeup SIGIO sent Flag set again The important part of the logic is in n_tty.c and tty_io.c Alan