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virtio-serial: add missing virtio_detach_element() call

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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device is reset then virtqueue elements are no longer valid.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.shah@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Tested-by: Ladi Prosek <lprosek@redhat.com>
Reviewed-by: Ladi Prosek <lprosek@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
Stefan Hajnoczi 2016-09-19 14:28:05 +01:00 committed by Michael S. Tsirkin
parent 97b93c8ad2
commit d4c19cdeeb
1 changed files with 14 additions and 0 deletions
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14
hw/char/virtio-serial-bus.c
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@ -145,6 +145,15 @@ 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)
{
@ -267,6 +276,7 @@ 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);
@ -591,6 +601,9 @@ 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) {
@ -901,6 +914,7 @@ 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);