virtio: console: Unblock poll on port hot-unplug

When a port is hot-unplugged while an app is blocked on poll(), unblock
the poll() and return.

Signed-off-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

1 files changed, 4 insertions, 0 deletions

diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
index 92f1f65d57a9..47b710ca4ab3 100644
--- a/drivers/char/virtio_console.c
+++ b/drivers/char/virtio_console.c
@@ -663,6 +663,10 @@ static unsigned int port_fops_poll(struct file *filp, poll_table *wait)
         port = filp->private_data;
         poll_wait(filp, &port->waitqueue, wait);
 
+        if (!port->guest_connected) {
+                /* Port got unplugged */
+                return POLLHUP;
+        }
         ret = 0;
         if (!will_read_block(port))
                 ret |= POLLIN | POLLRDNORM;