Commit d4c19cde authored by Stefan Hajnoczi's avatar Stefan Hajnoczi Committed by Michael S. Tsirkin
Browse files

virtio-serial: add missing virtio_detach_element() call 



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device is reset then virtqueue elements are no longer valid.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: default avatarStefan Hajnoczi <stefanha@redhat.com>
Tested-by: default avatarLadi Prosek <lprosek@redhat.com>
Reviewed-by: default avatarLadi Prosek <lprosek@redhat.com>
Reviewed-by: default avatarMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: default avatarMichael S. Tsirkin <mst@redhat.com>
parent 97b93c8a

hw/char/virtio-serial-bus.c

+14 −0
Original line number Diff line number Diff line
@@ -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);