virtio-serial-bus: let chardev know the exact number of bytes requested

Using the virtqueue_avail_bytes() function had an unnecessarily
crippling effect on the number of bytes needed by the guest as reported
to the chardev layer in the can_read() callback.

Using the new virtqueue_get_avail_bytes() function will let us advertise
the exact number of bytes we can send to the guest.

Signed-off-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
Amit Shah 2012-09-25 00:05:16 +05:30 committed by Michael S. Tsirkin
parent 0d8d769085
commit ad3005ad8c

View File

@ -287,6 +287,7 @@ ssize_t virtio_serial_write(VirtIOSerialPort *port, const uint8_t *buf,
size_t virtio_serial_guest_ready(VirtIOSerialPort *port)
{
VirtQueue *vq = port->ivq;
unsigned int bytes;
if (!virtio_queue_ready(vq) ||
!(port->vser->vdev.status & VIRTIO_CONFIG_S_DRIVER_OK) ||
@ -296,14 +297,8 @@ size_t virtio_serial_guest_ready(VirtIOSerialPort *port)
if (use_multiport(port->vser) && !port->guest_connected) {
return 0;
}
if (virtqueue_avail_bytes(vq, 4096, 0)) {
return 4096;
}
if (virtqueue_avail_bytes(vq, 1, 0)) {
return 1;
}
return 0;
virtqueue_get_avail_bytes(vq, &bytes, NULL);
return bytes;
}
static void flush_queued_data_bh(void *opaque)