virtio: console: Add ability to hot-unplug ports

Remove port data; deregister from the hvc core if it's a console port.

Signed-off-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Amit Shah 2009-12-21 22:27:31 +05:30 committed by Rusty Russell
parent 7f5d810dac
commit 1f7aa42d16
2 changed files with 64 additions and 2 deletions

View File

@ -783,6 +783,36 @@ static struct attribute_group port_attribute_group = {
.attrs = port_sysfs_entries,
};
/* Remove all port-specific data. */
static int remove_port(struct port *port)
{
spin_lock_irq(&port->portdev->ports_lock);
list_del(&port->list);
spin_unlock_irq(&port->portdev->ports_lock);
if (is_console_port(port)) {
spin_lock_irq(&pdrvdata_lock);
list_del(&port->cons.list);
spin_unlock_irq(&pdrvdata_lock);
hvc_remove(port->cons.hvc);
}
if (port->guest_connected)
send_control_msg(port, VIRTIO_CONSOLE_PORT_OPEN, 0);
while (port->in_vq->vq_ops->detach_unused_buf(port->in_vq))
;
sysfs_remove_group(&port->dev->kobj, &port_attribute_group);
device_destroy(pdrvdata.class, port->dev->devt);
cdev_del(&port->cdev);
discard_port_data(port);
kfree(port->name);
kfree(port);
return 0;
}
/* Any private messages that the Host and Guest want to share */
static void handle_control_message(struct ports_device *portdev,
struct port_buffer *buf)
@ -854,6 +884,32 @@ static void handle_control_message(struct ports_device *portdev,
err);
break;
case VIRTIO_CONSOLE_PORT_REMOVE:
/*
* Hot unplug the port. We don't decrement nr_ports
* since we don't want to deal with extra complexities
* of using the lowest-available port id: We can just
* pick up the nr_ports number as the id and not have
* userspace send it to us. This helps us in two
* ways:
*
* - We don't need to have a 'port_id' field in the
* config space when a port is hot-added. This is a
* good thing as we might queue up multiple hotplug
* requests issued in our workqueue.
*
* - Another way to deal with this would have been to
* use a bitmap of the active ports and select the
* lowest non-active port from that map. That
* bloats the already tight config space and we
* would end up artificially limiting the
* max. number of ports to sizeof(bitmap). Right
* now we can support 2^32 ports (as the port id is
* stored in a u32 type).
*
*/
remove_port(port);
break;
}
}
@ -1078,12 +1134,17 @@ static void config_work_handler(struct work_struct *work)
/*
* Port 0 got hot-added. Since we already did all the
* other initialisation for it, just tell the Host
* that the port is ready.
* that the port is ready if we find the port. In
* case the port was hot-removed earlier, we call
* add_port to add the port.
*/
struct port *port;
port = find_port_by_id(portdev, 0);
send_control_msg(port, VIRTIO_CONSOLE_PORT_READY, 1);
if (!port)
add_port(portdev, 0);
else
send_control_msg(port, VIRTIO_CONSOLE_PORT_READY, 1);
return;
}
if (virtconconf.nr_ports > portdev->config.max_nr_ports) {

View File

@ -41,6 +41,7 @@ struct virtio_console_control {
#define VIRTIO_CONSOLE_RESIZE 2
#define VIRTIO_CONSOLE_PORT_OPEN 3
#define VIRTIO_CONSOLE_PORT_NAME 4
#define VIRTIO_CONSOLE_PORT_REMOVE 5
#ifdef __KERNEL__
int __init virtio_cons_early_init(int (*put_chars)(u32, const char *, int));