From patchwork Mon Jun 6 12:49:34 2011 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Gerd Hoffmann X-Patchwork-Id: 98938 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from lists.gnu.org (lists.gnu.org [140.186.70.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTPS id 21596B6F59 for ; Tue, 7 Jun 2011 00:42:43 +1000 (EST) Received: from localhost ([::1]:37233 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1QTb0p-0006ZZ-CP for incoming@patchwork.ozlabs.org; Mon, 06 Jun 2011 10:42:39 -0400 Received: from eggs.gnu.org ([140.186.70.92]:43974) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1QTZFe-0002PX-IC for qemu-devel@nongnu.org; Mon, 06 Jun 2011 08:49:51 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1QTZFZ-0007g0-4l for qemu-devel@nongnu.org; Mon, 06 Jun 2011 08:49:49 -0400 Received: from mx1.redhat.com ([209.132.183.28]:13387) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1QTZFY-0007fB-FX for qemu-devel@nongnu.org; Mon, 06 Jun 2011 08:49:44 -0400 Received: from int-mx01.intmail.prod.int.phx2.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id p56Cnh8p016989 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Mon, 6 Jun 2011 08:49:43 -0400 Received: from rincewind.home.kraxel.org (vpn2-8-52.ams2.redhat.com [10.36.8.52]) by int-mx01.intmail.prod.int.phx2.redhat.com (8.13.8/8.13.8) with ESMTP id p56CnfRh031932; Mon, 6 Jun 2011 08:49:42 -0400 Received: by rincewind.home.kraxel.org (Postfix, from userid 500) id 34D88400E4; Mon, 6 Jun 2011 14:49:40 +0200 (CEST) From: Gerd Hoffmann To: qemu-devel@nongnu.org Date: Mon, 6 Jun 2011 14:49:34 +0200 Message-Id: <1307364580-28385-2-git-send-email-kraxel@redhat.com> In-Reply-To: <1307364580-28385-1-git-send-email-kraxel@redhat.com> References: <1307364580-28385-1-git-send-email-kraxel@redhat.com> X-Scanned-By: MIMEDefang 2.67 on 10.5.11.11 X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 209.132.183.28 Cc: Hans de Goede , Gerd Hoffmann Subject: [Qemu-devel] [PATCH 1/7] spice-qemu-char: Fix flow control in client -> guest direction X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org From: Hans de Goede In the old spice-vmc device we used to have: last_out = virtio_serial_write(&svc->port, p, MIN(len, VMC_MAX_HOST_WRITE)); if (last_out > 0) ... Now in the chardev backend we have: last_out = MIN(len, VMC_MAX_HOST_WRITE); qemu_chr_read(scd->chr, p, last_out); if (last_out > 0) { ... Which causes us to no longer detect if the virtio port is not ready to receive data from us. chardev actually has a mechanism to detect this, but it requires a separate call to qemu_chr_can_read, before calling qemu_chr_read (which return void). This patch uses qemu_chr_can_read to fix the flow control from client to guest. Signed-off-by: Hans de Goede Signed-off-by: Gerd Hoffmann --- spice-qemu-char.c | 11 +++++------ 1 files changed, 5 insertions(+), 6 deletions(-) diff --git a/spice-qemu-char.c b/spice-qemu-char.c index fa15a71..605c241 100644 --- a/spice-qemu-char.c +++ b/spice-qemu-char.c @@ -36,14 +36,13 @@ static int vmc_write(SpiceCharDeviceInstance *sin, const uint8_t *buf, int len) while (len > 0) { last_out = MIN(len, VMC_MAX_HOST_WRITE); - qemu_chr_read(scd->chr, p, last_out); - if (last_out > 0) { - out += last_out; - len -= last_out; - p += last_out; - } else { + if (qemu_chr_can_read(scd->chr) < last_out) { break; } + qemu_chr_read(scd->chr, p, last_out); + out += last_out; + len -= last_out; + p += last_out; } dprintf(scd, 3, "%s: %lu/%zd\n", __func__, out, len + out);