[PATCH 06/10] virtio: console: fix race in port_fops_poll() and port unplug

[Amit Shah <amit.shah@redhat.com>]

Between poll() being called and processed, the port can be unplugged.
Check if this happened, and bail out.

Signed-off-by: Amit Shah <amit.shah@redhat.com>
---
 drivers/char/virtio_console.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
index 7728af9..1d4b748 100644
--- a/drivers/char/virtio_console.c
+++ b/drivers/char/virtio_console.c
@@ -967,6 +967,10 @@ static unsigned int port_fops_poll(struct file *filp, poll_table *wait)
 	unsigned int ret;
 
 	port = filp->private_data;
+	if (!port->guest_connected) {
+		/* Port was unplugged before we could proceed */
+		return POLLHUP;
+	}
 	poll_wait(filp, &port->waitqueue, wait);
 
 	if (!port->guest_connected) {
-- 
1.8.1.4