From patchwork Wed Mar 31 07:34:08 2010 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Amit Shah X-Patchwork-Id: 49096 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 956A0B7C09 for ; Wed, 31 Mar 2010 19:24:14 +1100 (EST) Received: from localhost ([127.0.0.1]:46499 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1NwtDg-0005WV-0Y for incoming@patchwork.ozlabs.org; Wed, 31 Mar 2010 04:24:12 -0400 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1NwsTl-0006RZ-HT for qemu-devel@nongnu.org; Wed, 31 Mar 2010 03:36:45 -0400 Received: from [140.186.70.92] (port=33397 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1NwsTh-0006P3-C7 for qemu-devel@nongnu.org; Wed, 31 Mar 2010 03:36:45 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.69) (envelope-from ) id 1NwsTd-0007GR-Qa for qemu-devel@nongnu.org; Wed, 31 Mar 2010 03:36:41 -0400 Received: from mx1.redhat.com ([209.132.183.28]:32743) by eggs.gnu.org with esmtp (Exim 4.69) (envelope-from ) id 1NwsTd-0007G2-Gc for qemu-devel@nongnu.org; Wed, 31 Mar 2010 03:36:37 -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 (8.13.8/8.13.8) with ESMTP id o2V7aa3C026745 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Wed, 31 Mar 2010 03:36:36 -0400 Received: from localhost (vpn-235-197.phx2.redhat.com [10.3.235.197]) by int-mx01.intmail.prod.int.phx2.redhat.com (8.13.8/8.13.8) with ESMTP id o2V7aYHu000529; Wed, 31 Mar 2010 03:36:35 -0400 From: Amit Shah To: qemu list Date: Wed, 31 Mar 2010 13:04:08 +0530 Message-Id: <1270020848-15526-18-git-send-email-amit.shah@redhat.com> In-Reply-To: <1270020848-15526-17-git-send-email-amit.shah@redhat.com> References: <1270020848-15526-1-git-send-email-amit.shah@redhat.com> <1270020848-15526-2-git-send-email-amit.shah@redhat.com> <1270020848-15526-3-git-send-email-amit.shah@redhat.com> <1270020848-15526-4-git-send-email-amit.shah@redhat.com> <1270020848-15526-5-git-send-email-amit.shah@redhat.com> <1270020848-15526-6-git-send-email-amit.shah@redhat.com> <1270020848-15526-7-git-send-email-amit.shah@redhat.com> <1270020848-15526-8-git-send-email-amit.shah@redhat.com> <1270020848-15526-9-git-send-email-amit.shah@redhat.com> <1270020848-15526-10-git-send-email-amit.shah@redhat.com> <1270020848-15526-11-git-send-email-amit.shah@redhat.com> <1270020848-15526-12-git-send-email-amit.shah@redhat.com> <1270020848-15526-13-git-send-email-amit.shah@redhat.com> <1270020848-15526-14-git-send-email-amit.shah@redhat.com> <1270020848-15526-15-git-send-email-amit.shah@redhat.com> <1270020848-15526-16-git-send-email-amit.shah@redhat.com> <1270020848-15526-17-git-send-email-amit.shah@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. Cc: Amit Shah , "Michael S. Tsirkin" , Gerd Hoffmann , Juan Quintela Subject: [Qemu-devel] [PATCH 17/17] virtio-serial: Implement flow control for individual ports 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 Individual ports can now signal to the virtio-serial core to stop sending data if the ports cannot immediately handle new data. When a port later unthrottles, any data queued up in the virtqueue are sent to the port. Signed-off-by: Amit Shah --- hw/virtio-serial-bus.c | 24 ++++++++++++++++++++++++ hw/virtio-serial.h | 9 +++++++++ 2 files changed, 33 insertions(+), 0 deletions(-) diff --git a/hw/virtio-serial-bus.c b/hw/virtio-serial-bus.c index 757de7c..7b57ed8 100644 --- a/hw/virtio-serial-bus.c +++ b/hw/virtio-serial-bus.c @@ -187,6 +187,11 @@ int virtio_serial_close(VirtIOSerialPort *port) port->host_connected = false; send_control_event(port, VIRTIO_CONSOLE_PORT_OPEN, 0); + /* + * If there's any data the guest sent which the app didn't + * consume, discard it. + */ + flush_queued_data(port, true); return 0; } @@ -226,6 +231,21 @@ size_t virtio_serial_guest_ready(VirtIOSerialPort *port) return 0; } +void virtio_serial_throttle_port(VirtIOSerialPort *port, bool throttle) +{ + if (!port) { + return; + } + + if (throttle) { + port->throttled = true; + return; + } + + port->throttled = false; + flush_queued_data(port, false); +} + /* Guest wants to notify us of some event */ static void handle_control_message(VirtIOSerial *vser, void *buf, size_t len) { @@ -382,6 +402,10 @@ static void handle_output(VirtIODevice *vdev, VirtQueue *vq) discard = true; } + if (!discard && port->throttled) { + return; + } + flush_queued_data(port, discard); } diff --git a/hw/virtio-serial.h b/hw/virtio-serial.h index 62d76a2..a93b545 100644 --- a/hw/virtio-serial.h +++ b/hw/virtio-serial.h @@ -110,6 +110,8 @@ struct VirtIOSerialPort { bool guest_connected; /* Is this device open for IO on the host? */ bool host_connected; + /* Do apps not want to receive data? */ + bool throttled; }; struct VirtIOSerialPortInfo { @@ -173,4 +175,11 @@ ssize_t virtio_serial_write(VirtIOSerialPort *port, const uint8_t *buf, */ size_t virtio_serial_guest_ready(VirtIOSerialPort *port); +/* + * Flow control: Ports can signal to the virtio-serial core to stop + * sending data or re-start sending data, depending on the 'throttle' + * value here. + */ +void virtio_serial_throttle_port(VirtIOSerialPort *port, bool throttle); + #endif