From patchwork Tue Apr 27 12:34:11 2010 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Amit Shah X-Patchwork-Id: 51078 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 F0BAFB7D5B for ; Tue, 27 Apr 2010 23:18:57 +1000 (EST) Received: from localhost ([127.0.0.1]:55909 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1O6kg2-0007PV-BL for incoming@patchwork.ozlabs.org; Tue, 27 Apr 2010 09:18:14 -0400 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1O6k1x-0006I9-S2 for qemu-devel@nongnu.org; Tue, 27 Apr 2010 08:36:49 -0400 Received: from [140.186.70.92] (port=51544 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1O6k1w-0006HF-Bd for qemu-devel@nongnu.org; Tue, 27 Apr 2010 08:36:49 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.69) (envelope-from ) id 1O6k1o-0002st-Kq for qemu-devel@nongnu.org; Tue, 27 Apr 2010 08:36:47 -0400 Received: from mx1.redhat.com ([209.132.183.28]:1866) by eggs.gnu.org with esmtp (Exim 4.69) (envelope-from ) id 1O6k1n-0002sc-3L for qemu-devel@nongnu.org; Tue, 27 Apr 2010 08:36:39 -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 o3RCaboq013594 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK); Tue, 27 Apr 2010 08:36:37 -0400 Received: from localhost (vpn-238-78.phx2.redhat.com [10.3.238.78]) by int-mx01.intmail.prod.int.phx2.redhat.com (8.13.8/8.13.8) with ESMTP id o3RCaZGW021747; Tue, 27 Apr 2010 08:36:36 -0400 From: Amit Shah To: Anthony Liguori Date: Tue, 27 Apr 2010 18:04:11 +0530 Message-Id: <1272371652-23087-18-git-send-email-amit.shah@redhat.com> In-Reply-To: <1272371652-23087-17-git-send-email-amit.shah@redhat.com> References: <1272371652-23087-1-git-send-email-amit.shah@redhat.com> <1272371652-23087-2-git-send-email-amit.shah@redhat.com> <1272371652-23087-3-git-send-email-amit.shah@redhat.com> <1272371652-23087-4-git-send-email-amit.shah@redhat.com> <1272371652-23087-5-git-send-email-amit.shah@redhat.com> <1272371652-23087-6-git-send-email-amit.shah@redhat.com> <1272371652-23087-7-git-send-email-amit.shah@redhat.com> <1272371652-23087-8-git-send-email-amit.shah@redhat.com> <1272371652-23087-9-git-send-email-amit.shah@redhat.com> <1272371652-23087-10-git-send-email-amit.shah@redhat.com> <1272371652-23087-11-git-send-email-amit.shah@redhat.com> <1272371652-23087-12-git-send-email-amit.shah@redhat.com> <1272371652-23087-13-git-send-email-amit.shah@redhat.com> <1272371652-23087-14-git-send-email-amit.shah@redhat.com> <1272371652-23087-15-git-send-email-amit.shah@redhat.com> <1272371652-23087-16-git-send-email-amit.shah@redhat.com> <1272371652-23087-17-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 , qemu list , Juan Quintela Subject: [Qemu-devel] [PATCH v6 17/18] 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 | 50 ++++++++++++++++++++++++++++++++++++++++++----- hw/virtio-serial.h | 9 ++++++++ 2 files changed, 53 insertions(+), 6 deletions(-) diff --git a/hw/virtio-serial-bus.c b/hw/virtio-serial-bus.c index 8d07152..97694d5 100644 --- a/hw/virtio-serial-bus.c +++ b/hw/virtio-serial-bus.c @@ -111,14 +111,14 @@ static size_t write_to_port(VirtIOSerialPort *port, return offset; } -static void flush_queued_data(VirtIOSerialPort *port, VirtQueue *vq, - VirtIODevice *vdev, bool discard) +static void do_flush_queued_data(VirtIOSerialPort *port, VirtQueue *vq, + VirtIODevice *vdev, bool discard) { VirtQueueElement elem; assert(port || discard); - while (virtqueue_pop(vq, &elem)) { + while ((discard || !port->throttled) && virtqueue_pop(vq, &elem)) { uint8_t *buf; size_t ret, buf_size; @@ -135,6 +135,13 @@ static void flush_queued_data(VirtIOSerialPort *port, VirtQueue *vq, virtio_notify(vdev, vq); } +static void flush_queued_data(VirtIOSerialPort *port, bool discard) +{ + assert(port || discard); + + do_flush_queued_data(port, port->ovq, &port->vser->vdev, discard); +} + static size_t send_control_msg(VirtIOSerialPort *port, void *buf, size_t len) { VirtQueueElement elem; @@ -186,6 +193,13 @@ 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; @@ -227,6 +241,20 @@ 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) { @@ -380,7 +408,11 @@ static void handle_output(VirtIODevice *vdev, VirtQueue *vq) discard = true; } - flush_queued_data(port, vq, vdev, discard); + if (!discard && port->throttled) { + return; + } + + do_flush_queued_data(port, vq, vdev, discard); } static void handle_input(VirtIODevice *vdev, VirtQueue *vq) @@ -555,6 +587,8 @@ 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 */ @@ -592,13 +626,17 @@ 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