virtio: console: Remove cached data on port close
Remove any data that we might have in a port's inbuf when closing a port
or when any data is received when a port is closed.
Signed-off-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
index 99d182b..5506ff8 100644
--- a/drivers/char/virtio_console.c
+++ b/drivers/char/virtio_console.c
@@ -316,6 +316,31 @@
return ret;
}
+/* Discard any unread data this port has. Callers lockers. */
+static void discard_port_data(struct port *port)
+{
+ struct port_buffer *buf;
+ struct virtqueue *vq;
+ unsigned int len;
+
+ vq = port->in_vq;
+ if (port->inbuf)
+ buf = port->inbuf;
+ else
+ buf = vq->vq_ops->get_buf(vq, &len);
+
+ if (!buf)
+ return;
+
+ if (add_inbuf(vq, buf) < 0) {
+ buf->len = buf->offset = 0;
+ dev_warn(port->dev, "Error adding buffer back to vq\n");
+ return;
+ }
+
+ port->inbuf = NULL;
+}
+
static bool port_has_data(struct port *port)
{
unsigned long flags;
@@ -534,8 +559,13 @@
/* Notify host of port being closed */
send_control_msg(port, VIRTIO_CONSOLE_PORT_OPEN, 0);
+ spin_lock_irq(&port->inbuf_lock);
port->guest_connected = false;
+ discard_port_data(port);
+
+ spin_unlock_irq(&port->inbuf_lock);
+
return 0;
}
@@ -872,6 +902,16 @@
spin_lock_irqsave(&port->inbuf_lock, flags);
port->inbuf = get_inbuf(port);
+ /*
+ * Don't queue up data when port is closed. This condition
+ * can be reached when a console port is not yet connected (no
+ * tty is spawned) and the host sends out data to console
+ * ports. For generic serial ports, the host won't
+ * (shouldn't) send data till the guest is connected.
+ */
+ if (!port->guest_connected)
+ discard_port_data(port);
+
spin_unlock_irqrestore(&port->inbuf_lock, flags);
wake_up_interruptible(&port->waitqueue);