From 0cf30e5b630f838073eb583ce1c09f9421c74042 Mon Sep 17 00:00:00 2001 From: Amit Shah Date: Tue, 27 Apr 2010 09:07:44 -0300 Subject: [PATCH 17/20] virtio-serial: Implement flow control for individual ports RH-Author: Amit Shah Message-id: <1272359264-8464-18-git-send-email-amit.shah@redhat.com> Patchwork-id: 8863 O-Subject: [RHEL6 PATCH v4 17/17] virtio-serial: Implement flow control for individual ports Bugzilla: 574296 RH-Acked-by: Gerd Hoffmann RH-Acked-by: Juan Quintela RH-Acked-by: Alon Levy 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. Add a bus info message for showing port's throttled status: show whether a port is throttled in 'info qtree'. Bugzilla: 574296 Upstream: Signed-off-by: Amit Shah --- hw/virtio-serial-bus.c | 37 ++++++++++++++++++++++++++++++++++--- hw/virtio-serial.h | 9 +++++++++ 2 files changed, 43 insertions(+), 3 deletions(-) Signed-off-by: Eduardo Habkost --- 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 -- 1.7.0.3