Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261412AbVBRQmX (ORCPT ); Fri, 18 Feb 2005 11:42:23 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261407AbVBRQmX (ORCPT ); Fri, 18 Feb 2005 11:42:23 -0500 Received: from adsl-69-149-197-17.dsl.austtx.swbell.net ([69.149.197.17]:57483 "EHLO gw.microgate.com") by vger.kernel.org with ESMTP id S261404AbVBRQmT (ORCPT ); Fri, 18 Feb 2005 11:42:19 -0500 Message-ID: <42161A9D.1080406@microgate.com> Date: Fri, 18 Feb 2005 10:41:01 -0600 From: Paul Fulghum User-Agent: Mozilla Thunderbird 1.0 (Windows/20041206) X-Accept-Language: en-us, en MIME-Version: 1.0 To: franck.bui-huu@innova-card.com CC: linux-kernel@vger.kernel.org, linux-os@analogic.com, pmarques@grupopie.com Subject: Re: [TTY] 2 points seems strange to me. References: <20050217175150.D8E015B874@frankbuss.de> <20050217181241.A22752@flint.arm.linux.org.uk> <4215B5AC.4050600@innova-card.com> <42160290.3070000@microgate.com> <421617D3.4080207@innova-card.com> In-Reply-To: <421617D3.4080207@innova-card.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1148 Lines: 31 Franck Bui-Huu wrote: > I was looking at driver for 8250 in 8250.c file and at the end > of "receive_chars" interrupt handler, it calls "tty_flip_buffer_push" > even if "tty->low_latency" is set since no such test is done before > the call... Yes this is a known problem. In the case of SMP kernel and low_latency, and 8250.c, this causes a dead lock. This has resurfaced again and again for many months from different sources. There is disagreement on what code is in error and what should be fixed. So it stays broken. > I was also wondering why not always calling "schedule_delayed_work" > whatever the state of "tty->latency"? If low_latency is set and you are not calling from interrupt, then calling work directly speeds processing. I submitted a patch that forced schedule_delayed_work if in interrupt context to avoid this problem. It was rejected. -- Paul Fulghum Microgate Systems, Ltd. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/