From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S264477AbUEaAdX (ORCPT ); Sun, 30 May 2004 20:33:23 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S264482AbUEaAdX (ORCPT ); Sun, 30 May 2004 20:33:23 -0400 Received: from mx1.redhat.com ([66.187.233.31]:38597 "EHLO mx1.redhat.com") by vger.kernel.org with ESMTP id S264477AbUEaAdV (ORCPT ); Sun, 30 May 2004 20:33:21 -0400 Date: Sun, 30 May 2004 17:32:52 -0700 From: "David S. Miller" To: Benjamin Herrenschmidt Cc: akpm@osdl.org, linux-kernel@vger.kernel.org, rmk+serial@arm.linux.org.uk Subject: Re: [PATCH] Fix typo in pmac_zilog Message-Id: <20040530173252.4a040e99.davem@redhat.com> In-Reply-To: <1085901218.10399.11.camel@gaston> References: <1085715655.6320.138.camel@gaston> <20040529234258.42a2dc64.davem@redhat.com> <1085901218.10399.11.camel@gaston> X-Mailer: Sylpheed version 0.9.10 (GTK+ 1.2.10; sparc-unknown-linux-gnu) X-Face: "_;p5u5aPsO,_Vsx"^v-pEq09'CU4&Dc1$fQExov$62l60cgCc%FnIwD=.UF^a>?5'9Kn[;433QFVV9M..2eN.@4ZWPGbdi<=?[:T>y?SD(R*-3It"Vj:)"dP Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Sun, 30 May 2004 17:13:38 +1000 Benjamin Herrenschmidt wrote: > There is a deadlock issue. I triggered once when I had a bug where the > driver was flooding the input with zero's. All serial drivers seem to be > affected. Apparently, tty_flip_* may call back into your write() routine Yes indeed, one code path is: tty_flip_buffer_push() if (tty->low_latency) flush_to_ldisc() { tty->ldisc.receive_buf() == n_tty_receive_buf() { ... n_tty_receive_char() { ... start_tty() { tty->driver->start() == uart_start() and that's where we try to grab the uart port lock again. It seems lots of serial drivers have this bug, even 8250.c :-) I'll fix up the Sparc drivers meanwhile.