Commit 96f97a83 authored Jul 29, 2013 by Amit Shah Committed by Rusty Russell Jul 29, 2013

virtio: console: return -ENODEV on all read operations after unplug



If a port gets unplugged while a user is blocked on read(), -ENODEV is
returned.  However, subsequent read()s returned 0, indicating there's no
host-side connection (but not indicating the device went away).

This also happened when a port was unplugged and the user didn't have
any blocking operation pending.  If the user didn't monitor the SIGIO
signal, they won't have a chance to find out if the port went away.

Fix by returning -ENODEV on all read()s after the port gets unplugged.
write() already behaves this way.

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

parent 92d34538

drivers/char/virtio_console.c

+5 −1

Original line number	Original line	Diff line number	Diff line
	@@ -749,6 +749,10 @@ static ssize_t port_fops_read(struct file filp, char __user ubuf,

	port = filp->private_data;		port = filp->private_data;

			/* Port is hot-unplugged. */
			if (!port->guest_connected)
			return -ENODEV;

	if (!port_has_data(port)) {		if (!port_has_data(port)) {
	/*		/*
	* If nothing's connected on the host just return 0 in		* If nothing's connected on the host just return 0 in
	@@ -765,7 +769,7 @@ static ssize_t port_fops_read(struct file filp, char __user ubuf,
	if (ret < 0)		if (ret < 0)
	return ret;		return ret;
	}		}
	/* Port got hot-unplugged. */		/* Port got hot-unplugged while we were waiting above. */
	if (!port->guest_connected)		if (!port->guest_connected)
	return -ENODEV;		return -ENODEV;
	/*		/*