From patchwork Tue Apr 20 16:56:06 2010 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexander Graf X-Patchwork-Id: 50548 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from lists.gnu.org (lists.gnu.org [199.232.76.165]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTPS id 68472B7D08 for ; Wed, 21 Apr 2010 02:59:44 +1000 (EST) Received: from localhost ([127.0.0.1]:39047 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1O4GnV-0004P3-Su for incoming@patchwork.ozlabs.org; Tue, 20 Apr 2010 12:59:41 -0400 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1O4GkD-0003iM-7m for qemu-devel@nongnu.org; Tue, 20 Apr 2010 12:56:17 -0400 Received: from [140.186.70.92] (port=58864 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1O4GkB-0003hO-Fx for qemu-devel@nongnu.org; Tue, 20 Apr 2010 12:56:16 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.69) (envelope-from ) id 1O4Gk6-0004Gs-E7 for qemu-devel@nongnu.org; Tue, 20 Apr 2010 12:56:15 -0400 Received: from cantor.suse.de ([195.135.220.2]:54087 helo=mx1.suse.de) by eggs.gnu.org with esmtp (Exim 4.69) (envelope-from ) id 1O4Gk6-0004G3-8T for qemu-devel@nongnu.org; Tue, 20 Apr 2010 12:56:10 -0400 Received: from relay1.suse.de (charybdis-ext.suse.de [195.135.221.2]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.suse.de (Postfix) with ESMTP id 6E01994109; Tue, 20 Apr 2010 18:56:07 +0200 (CEST) From: Alexander Graf To: qemu-devel Developers Date: Tue, 20 Apr 2010 18:56:06 +0200 Message-Id: <1271782566-16420-1-git-send-email-agraf@suse.de> X-Mailer: git-send-email 1.6.0.2 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.4-2.6 Cc: Bastian Blank , Aurelien Jarno Subject: [Qemu-devel] [PATCH] [RESEND] Make char muxer more robust wrt small FIFOs X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Virtio-Console can only process one character at a time. Using it on S390 gave me strage "lags" where I got the character I pressed before when pressing one. So I typed in "abc" and only received "a", then pressed "d" but the guest received "b" and so on. While the stdio driver calls a poll function that just processes on its queue in case virtio-console can't take multiple characters at once, the muxer does not have such callbacks, so it can't empty its queue. To work around that limitation, I introduced a new timer that only gets active when the guest can not receive any more characters. In that case it polls again after a while to check if the guest is now receiving input. This patch fixes input when using -nographic on s390 for me. --- Please consider for stable. --- qemu-char.c | 10 ++++++++++ 1 files changed, 10 insertions(+), 0 deletions(-) diff --git a/qemu-char.c b/qemu-char.c index 05df971..ce9df3a 100644 --- a/qemu-char.c +++ b/qemu-char.c @@ -235,6 +235,7 @@ typedef struct { IOEventHandler *chr_event[MAX_MUX]; void *ext_opaque[MAX_MUX]; CharDriverState *drv; + QEMUTimer *accept_timer; int focus; int mux_cnt; int term_got_escape; @@ -396,6 +397,13 @@ static void mux_chr_accept_input(CharDriverState *chr) d->chr_read[m](d->ext_opaque[m], &d->buffer[m][d->cons[m]++ & MUX_BUFFER_MASK], 1); } + + /* We're still not able to sync producer and consumer, so let's wait a bit + and try again by then. */ + if (d->prod[m] != d->cons[m]) { + qemu_mod_timer(d->accept_timer, qemu_get_clock(vm_clock) + + (int64_t)100000); + } } static int mux_chr_can_read(void *opaque) @@ -478,6 +486,8 @@ static CharDriverState *qemu_chr_open_mux(CharDriverState *drv) chr->opaque = d; d->drv = drv; d->focus = -1; + d->accept_timer = qemu_new_timer(vm_clock, + (QEMUTimerCB*)mux_chr_accept_input, chr); chr->chr_write = mux_chr_write; chr->chr_update_read_handler = mux_chr_update_read_handler; chr->chr_accept_input = mux_chr_accept_input;