virtio: console: Make read() return -ENODEV on hot-unplug

When a port is hot-unplugged while an app was blocked on a read() call,
the call was unblocked but would not get an error returned.

Return -ENODEV to ensure the app knows the port has gone away.

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 47b710c..e17ecf5 100644 (file)
--- a/drivers/char/virtio_console.c
+++ b/drivers/char/virtio_console.c
@@ -582,6 +582,9 @@ static ssize_t port_fops_read(struct file *filp, char __user *ubuf,
                if (ret < 0)
                        return ret;
        }
+       /* Port got hot-unplugged. */
+       if (!port->guest_connected)
+               return -ENODEV;
        /*
         * We could've received a disconnection message while we were
         * waiting for more data.