From patchwork Wed Apr 14 05:28:37 2010 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Amit Shah X-Patchwork-Id: 50114 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 93DA9B7D19 for ; Wed, 14 Apr 2010 16:20:45 +1000 (EST) Received: from localhost ([127.0.0.1]:60249 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1O1vxo-0001ya-7H for incoming@patchwork.ozlabs.org; Wed, 14 Apr 2010 02:20:40 -0400 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1O1vCV-0002e5-Ha for qemu-devel@nongnu.org; Wed, 14 Apr 2010 01:31:47 -0400 Received: from [140.186.70.92] (port=49170 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1O1vCS-0002cJ-Fj for qemu-devel@nongnu.org; Wed, 14 Apr 2010 01:31:46 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.69) (envelope-from ) id 1O1vCQ-00066Z-KI for qemu-devel@nongnu.org; Wed, 14 Apr 2010 01:31:44 -0400 Received: from mx1.redhat.com ([209.132.183.28]:12098) by eggs.gnu.org with esmtp (Exim 4.69) (envelope-from ) id 1O1vCQ-00066P-CF for qemu-devel@nongnu.org; Wed, 14 Apr 2010 01:31:42 -0400 Received: from int-mx08.intmail.prod.int.phx2.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.21]) by mx1.redhat.com (8.13.8/8.13.8) with ESMTP id o3E5VeRc019555 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK); Wed, 14 Apr 2010 01:31:40 -0400 Received: from localhost (vpn-236-230.phx2.redhat.com [10.3.236.230]) by int-mx08.intmail.prod.int.phx2.redhat.com (8.13.8/8.13.8) with ESMTP id o3E5VXhZ001625; Wed, 14 Apr 2010 01:31:34 -0400 From: Amit Shah To: Anthony Liguori Date: Wed, 14 Apr 2010 10:58:37 +0530 Message-Id: <1271222917-7803-18-git-send-email-amit.shah@redhat.com> In-Reply-To: <1271222917-7803-17-git-send-email-amit.shah@redhat.com> References: <1271222917-7803-1-git-send-email-amit.shah@redhat.com> <1271222917-7803-2-git-send-email-amit.shah@redhat.com> <1271222917-7803-3-git-send-email-amit.shah@redhat.com> <1271222917-7803-4-git-send-email-amit.shah@redhat.com> <1271222917-7803-5-git-send-email-amit.shah@redhat.com> <1271222917-7803-6-git-send-email-amit.shah@redhat.com> <1271222917-7803-7-git-send-email-amit.shah@redhat.com> <1271222917-7803-8-git-send-email-amit.shah@redhat.com> <1271222917-7803-9-git-send-email-amit.shah@redhat.com> <1271222917-7803-10-git-send-email-amit.shah@redhat.com> <1271222917-7803-11-git-send-email-amit.shah@redhat.com> <1271222917-7803-12-git-send-email-amit.shah@redhat.com> <1271222917-7803-13-git-send-email-amit.shah@redhat.com> <1271222917-7803-14-git-send-email-amit.shah@redhat.com> <1271222917-7803-15-git-send-email-amit.shah@redhat.com> <1271222917-7803-16-git-send-email-amit.shah@redhat.com> <1271222917-7803-17-git-send-email-amit.shah@redhat.com> X-Scanned-By: MIMEDefang 2.67 on 10.5.11.21 X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. Cc: qemu list , Amit Shah , Gerd Hoffmann , Juan Quintela Subject: [Qemu-devel] [PATCH v5 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. Disable throttling once a port is closed (and we discard all the unconsumed buffers in the vq). The guest kernel can reclaim the buffers when it receives the port close event or when a port is being removed. Ensure we free up the buffers before we send out any events to the guest. Signed-off-by: Amit Shah --- hw/virtio-serial-bus.c | 37 ++++++++++++++++++++++++++++++++++--- hw/virtio-serial.h | 9 +++++++++ 2 files changed, 43 insertions(+), 3 deletions(-) diff --git a/hw/virtio-serial-bus.c b/hw/virtio-serial-bus.c index 0166780..de64154 100644 --- a/hw/virtio-serial-bus.c +++ b/hw/virtio-serial-bus.c @@ -117,7 +117,7 @@ static void flush_queued_data(VirtIOSerialPort *port, bool discard) VirtQueueElement elem; vq = port->ovq; - while (virtqueue_pop(vq, &elem)) { + while ((discard || !port->throttled) && virtqueue_pop(vq, &elem)) { uint8_t *buf; size_t ret, buf_size; @@ -185,6 +185,13 @@ int virtio_serial_open(VirtIOSerialPort *port) int virtio_serial_close(VirtIOSerialPort *port) { port->host_connected = false; + /* + * If there's any data the guest sent which the app didn't + * consume, reset the throttling flag and discard the data. + */ + port->throttled = false; + flush_queued_data(port, true); + send_control_event(port, VIRTIO_CONSOLE_PORT_OPEN, 0); return 0; @@ -226,6 +233,20 @@ size_t virtio_serial_guest_ready(VirtIOSerialPort *port) return 0; } +void virtio_serial_throttle_port(VirtIOSerialPort *port, bool throttle) +{ + if (!port) { + return; + } + + port->throttled = throttle; + if (throttle) { + return; + } + + 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) { @@ -379,6 +400,10 @@ static void handle_output(VirtIODevice *vdev, VirtQueue *vq) discard = true; } + if (!discard && port->throttled) { + return; + } + flush_queued_data(port, discard); } @@ -554,6 +579,8 @@ static void virtser_bus_dev_print(Monitor *mon, DeviceState *qdev, int indent) indent, "", port->guest_connected); monitor_printf(mon, "%*s dev-prop-int: host_connected: %d\n", indent, "", port->host_connected); + monitor_printf(mon, "%*s dev-prop-int: throttled: %d\n", + indent, "", port->throttled); } /* This function is only used if a port id is not provided by the user */ @@ -591,13 +618,17 @@ static void add_port(VirtIOSerial *vser, uint32_t port_id) static void remove_port(VirtIOSerial *vser, uint32_t port_id) { + VirtIOSerialPort *port; unsigned int i; i = port_id / 32; vser->ports_map[i] &= ~(1U << (port_id % 32)); - send_control_event(find_port_by_id(vser, port_id), - VIRTIO_CONSOLE_PORT_REMOVE, 1); + port = find_port_by_id(vser, port_id); + /* Flush out any unconsumed buffers first */ + flush_queued_data(port, true); + + send_control_event(port, VIRTIO_CONSOLE_PORT_REMOVE, 1); } static int virtser_port_qdev_init(DeviceState *qdev, DeviceInfo *base) 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