virtio: console: fix locking around send_sigio_to_port()

send_sigio_to_port() checks the value of guest_connected, which we
always modify under the inbuf_lock; make sure invocations of
send_sigio_to_port() have take the inbuf_lock around the call.

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 3572c5a..d5e2c70 100644 (file)
--- a/drivers/char/virtio_console.c
+++ b/drivers/char/virtio_console.c
@@ -1661,7 +1661,9 @@ static void handle_control_message(struct ports_device *portdev,
                 * If the guest is connected, it'll be interested in
                 * knowing the host connection state changed.
                 */
+               spin_lock_irq(&port->inbuf_lock);
                send_sigio_to_port(port);
+               spin_unlock_irq(&port->inbuf_lock);
                break;
        case VIRTIO_CONSOLE_PORT_NAME:
                /*
@@ -1781,13 +1783,13 @@ static void in_intr(struct virtqueue *vq)
        if (!port->guest_connected && !is_rproc_serial(port->portdev->vdev))
                discard_port_data(port);
 
+       /* Send a SIGIO indicating new data in case the process asked for it */
+       send_sigio_to_port(port);
+
        spin_unlock_irqrestore(&port->inbuf_lock, flags);
 
        wake_up_interruptible(&port->waitqueue);
 
-       /* Send a SIGIO indicating new data in case the process asked for it */
-       send_sigio_to_port(port);
-
        if (is_console_port(port) && hvc_poll(port->cons.hvc))
                hvc_kick();
 }