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Commit 1f7aa42d authored by Amit Shah's avatar Amit Shah Committed by Rusty Russell
Browse files

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: default avatarAmit Shah <amit.shah@redhat.com>
Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
parent 7f5d810d

drivers/char/virtio_console.c

+63 −2
Original line number Diff line number Diff line
@@ -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;

	}

}
@@ -1078,11 +1134,16 @@ 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);

		if (!port)

			add_port(portdev, 0);

		else

			send_control_msg(port, VIRTIO_CONSOLE_PORT_READY, 1);

		return;

	}

include/linux/virtio_console.h

+1 −0
Original line number Diff line number Diff line
@@ -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));