virtio: console: Add file operations to ports for open/read/write/poll

Allow guest userspace applications to open, read from, write to, poll
the ports via the char dev interface.

When a port gets opened, a notification is sent to the host via a
control message indicating a connection has been established. Similarly,
on closing of the port, a notification is sent indicating disconnection.

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 21:49:30 +05:30 коммит произвёл Rusty Russell
Родитель fb08bd274d
Коммит 2030fa496d
2 изменённых файлов: 164 добавлений и 1 удалений

Просмотреть файл

@ -19,11 +19,15 @@
#include <linux/cdev.h>
#include <linux/device.h>
#include <linux/err.h>
#include <linux/fs.h>
#include <linux/init.h>
#include <linux/list.h>
#include <linux/poll.h>
#include <linux/sched.h>
#include <linux/spinlock.h>
#include <linux/virtio.h>
#include <linux/virtio_console.h>
#include <linux/wait.h>
#include <linux/workqueue.h>
#include "hvc_console.h"
@ -163,8 +167,14 @@ struct port {
struct cdev cdev;
struct device *dev;
/* A waitqueue for poll() or blocking read operations */
wait_queue_head_t waitqueue;
/* The 'id' to identify the port with the Host */
u32 id;
/* Is the host device open */
bool host_connected;
};
/* This is the very early arch-specified put chars function. */
@ -417,6 +427,146 @@ static ssize_t fill_readbuf(struct port *port, char *out_buf, size_t out_count,
return out_count;
}
/* The condition that must be true for polling to end */
static bool wait_is_over(struct port *port)
{
return port_has_data(port) || !port->host_connected;
}
static ssize_t port_fops_read(struct file *filp, char __user *ubuf,
size_t count, loff_t *offp)
{
struct port *port;
ssize_t ret;
port = filp->private_data;
if (!port_has_data(port)) {
/*
* If nothing's connected on the host just return 0 in
* case of list_empty; this tells the userspace app
* that there's no connection
*/
if (!port->host_connected)
return 0;
if (filp->f_flags & O_NONBLOCK)
return -EAGAIN;
ret = wait_event_interruptible(port->waitqueue,
wait_is_over(port));
if (ret < 0)
return ret;
}
/*
* We could've received a disconnection message while we were
* waiting for more data.
*
* This check is not clubbed in the if() statement above as we
* might receive some data as well as the host could get
* disconnected after we got woken up from our wait. So we
* really want to give off whatever data we have and only then
* check for host_connected.
*/
if (!port_has_data(port) && !port->host_connected)
return 0;
return fill_readbuf(port, ubuf, count, true);
}
static ssize_t port_fops_write(struct file *filp, const char __user *ubuf,
size_t count, loff_t *offp)
{
struct port *port;
char *buf;
ssize_t ret;
port = filp->private_data;
count = min((size_t)(32 * 1024), count);
buf = kmalloc(count, GFP_KERNEL);
if (!buf)
return -ENOMEM;
ret = copy_from_user(buf, ubuf, count);
if (ret) {
ret = -EFAULT;
goto free_buf;
}
ret = send_buf(port, buf, count);
free_buf:
kfree(buf);
return ret;
}
static unsigned int port_fops_poll(struct file *filp, poll_table *wait)
{
struct port *port;
unsigned int ret;
port = filp->private_data;
poll_wait(filp, &port->waitqueue, wait);
ret = 0;
if (port->inbuf)
ret |= POLLIN | POLLRDNORM;
if (port->host_connected)
ret |= POLLOUT;
if (!port->host_connected)
ret |= POLLHUP;
return ret;
}
static int port_fops_release(struct inode *inode, struct file *filp)
{
struct port *port;
port = filp->private_data;
/* Notify host of port being closed */
send_control_msg(port, VIRTIO_CONSOLE_PORT_OPEN, 0);
return 0;
}
static int port_fops_open(struct inode *inode, struct file *filp)
{
struct cdev *cdev = inode->i_cdev;
struct port *port;
port = container_of(cdev, struct port, cdev);
filp->private_data = port;
/*
* Don't allow opening of console port devices -- that's done
* via /dev/hvc
*/
if (is_console_port(port))
return -ENXIO;
/* Notify host of port being opened */
send_control_msg(filp->private_data, VIRTIO_CONSOLE_PORT_OPEN, 1);
return 0;
}
/*
* The file operations that we support: programs in the guest can open
* a console device, read from it, write to it, poll for data and
* close it. The devices are at
* /dev/vport<device number>p<port number>
*/
static const struct file_operations port_fops = {
.owner = THIS_MODULE,
.open = port_fops_open,
.read = port_fops_read,
.write = port_fops_write,
.poll = port_fops_poll,
.release = port_fops_release,
};
/*
* The put_chars() callback is pretty straightforward.
*
@ -560,6 +710,9 @@ int init_port_console(struct port *port)
list_add_tail(&port->cons.list, &pdrvdata.consoles);
spin_unlock_irq(&pdrvdata_lock);
/* Notify host of port being opened */
send_control_msg(port, VIRTIO_CONSOLE_PORT_OPEN, 1);
return 0;
}
@ -599,6 +752,10 @@ static void handle_control_message(struct ports_device *portdev,
port->cons.hvc->irq_requested = 1;
resize_console(port);
break;
case VIRTIO_CONSOLE_PORT_OPEN:
port->host_connected = cpkt->value;
wake_up_interruptible(&port->waitqueue);
break;
}
}
@ -645,6 +802,8 @@ static void in_intr(struct virtqueue *vq)
spin_unlock_irqrestore(&port->inbuf_lock, flags);
wake_up_interruptible(&port->waitqueue);
if (is_console_port(port) && hvc_poll(port->cons.hvc))
hvc_kick();
}
@ -697,10 +856,12 @@ static int add_port(struct ports_device *portdev, u32 id)
port->inbuf = NULL;
port->cons.hvc = NULL;
port->host_connected = false;
port->in_vq = portdev->in_vqs[port->id];
port->out_vq = portdev->out_vqs[port->id];
cdev_init(&port->cdev, NULL);
cdev_init(&port->cdev, &port_fops);
devt = MKDEV(portdev->chr_major, id);
err = cdev_add(&port->cdev, devt, 1);
@ -721,6 +882,7 @@ static int add_port(struct ports_device *portdev, u32 id)
}
spin_lock_init(&port->inbuf_lock);
init_waitqueue_head(&port->waitqueue);
inbuf = alloc_buf(PAGE_SIZE);
if (!inbuf) {

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@ -39,6 +39,7 @@ struct virtio_console_control {
#define VIRTIO_CONSOLE_PORT_READY 0
#define VIRTIO_CONSOLE_CONSOLE_PORT 1
#define VIRTIO_CONSOLE_RESIZE 2
#define VIRTIO_CONSOLE_PORT_OPEN 3
#ifdef __KERNEL__
int __init virtio_cons_early_init(int (*put_chars)(u32, const char *, int));