Ports enter a "throttled" state when writing to the chardev would block.
The current output VirtQueueElement is kept around until the chardev
becomes writable again.
There are several places in the virtio-serial lifecycle where the
VirtQueueElement should be thrown away. For example, if the virtio
device is reset then virtqueue elements are no longer valid.
This patch adds the discard_throttle_data() function to unmap the
scatter-gather list and decrement vq->inuse. This ensures that the
VirtQueueElement is freed properly.
Cc: amit.s...@redhat.com
Signed-off-by: Stefan Hajnoczi <stefa...@redhat.com>
---
hw/char/virtio-serial-bus.c | 14 ++++++++++++++
1 file changed, 14 insertions(+)
diff --git a/hw/char/virtio-serial-bus.c b/hw/char/virtio-serial-bus.c
index db57a38..35aa3c7 100644
--- a/hw/char/virtio-serial-bus.c
+++ b/hw/char/virtio-serial-bus.c
@@ -132,6 +132,15 @@ static void discard_vq_data(VirtQueue *vq, VirtIODevice
*vdev)
virtio_notify(vdev, vq);
}
+static void discard_throttle_data(VirtIOSerialPort *port)
+{
+ if (port->elem) {
+ virtqueue_detach_element(port->ovq, port->elem, 0);
+ g_free(port->elem);
+ port->elem = NULL;
+ }
+}
+
static void do_flush_queued_data(VirtIOSerialPort *port, VirtQueue *vq,
VirtIODevice *vdev)
{
@@ -254,6 +263,7 @@ int virtio_serial_close(VirtIOSerialPort *port)
* consume, reset the throttling flag and discard the data.
*/
port->throttled = false;
+ discard_throttle_data(port);
discard_vq_data(port->ovq, VIRTIO_DEVICE(port->vser));
send_control_event(port->vser, port->id, VIRTIO_CONSOLE_PORT_OPEN, 0);
@@ -554,6 +564,9 @@ static void guest_reset(VirtIOSerial *vser)
QTAILQ_FOREACH(port, &vser->ports, next) {
vsc = VIRTIO_SERIAL_PORT_GET_CLASS(port);
+
+ discard_throttle_data(port);
+
if (port->guest_connected) {
port->guest_connected = false;
if (vsc->set_guest_connected) {
@@ -864,6 +877,7 @@ static void remove_port(VirtIOSerial *vser, uint32_t
port_id)
assert(port);
/* Flush out any unconsumed buffers first */
+ discard_throttle_data(port);
discard_vq_data(port->ovq, VIRTIO_DEVICE(port->vser));
send_control_event(vser, port->id, VIRTIO_CONSOLE_PORT_REMOVE, 1);
--
2.7.4
