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authorAmit Shah <amit.shah@redhat.com>2009-11-26 11:25:38 +0530
committerRusty Russell <rusty@rustcorp.com.au>2010-02-24 14:22:55 +1030
commit3c7969ccb569968a79fab3729075751bc8fc2f78 (patch)
treec5f9d8362d8b448961cb0bf355a445e14646dec4 /drivers
parent2030fa496d74b49220308eaccf656e2338019cfd (diff)
downloadlinux-3c7969ccb569968a79fab3729075751bc8fc2f78.tar.bz2
virtio: console: Ensure only one process can have a port open at a time
Add a guest_connected field that ensures only one process can have a port open at a time. This also ensures we don't have a race when we later add support for dropping buffers when closing the char dev and buffer caching is turned off for the particular port. Signed-off-by: Amit Shah <amit.shah@redhat.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/char/virtio_console.c18
1 files changed, 17 insertions, 1 deletions
diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
index ece1546fbb20..5e3503a31312 100644
--- a/drivers/char/virtio_console.c
+++ b/drivers/char/virtio_console.c
@@ -175,6 +175,9 @@ struct port {
/* Is the host device open */
bool host_connected;
+
+ /* We should allow only one process to open a port */
+ bool guest_connected;
};
/* This is the very early arch-specified put chars function. */
@@ -528,6 +531,8 @@ static int port_fops_release(struct inode *inode, struct file *filp)
/* Notify host of port being closed */
send_control_msg(port, VIRTIO_CONSOLE_PORT_OPEN, 0);
+ port->guest_connected = false;
+
return 0;
}
@@ -546,6 +551,16 @@ static int port_fops_open(struct inode *inode, struct file *filp)
if (is_console_port(port))
return -ENXIO;
+ /* Allow only one process to open a particular port at a time */
+ spin_lock_irq(&port->inbuf_lock);
+ if (port->guest_connected) {
+ spin_unlock_irq(&port->inbuf_lock);
+ return -EMFILE;
+ }
+
+ port->guest_connected = true;
+ spin_unlock_irq(&port->inbuf_lock);
+
/* Notify host of port being opened */
send_control_msg(filp->private_data, VIRTIO_CONSOLE_PORT_OPEN, 1);
@@ -709,6 +724,7 @@ int init_port_console(struct port *port)
pdrvdata.next_vtermno++;
list_add_tail(&port->cons.list, &pdrvdata.consoles);
spin_unlock_irq(&pdrvdata_lock);
+ port->guest_connected = true;
/* Notify host of port being opened */
send_control_msg(port, VIRTIO_CONSOLE_PORT_OPEN, 1);
@@ -856,7 +872,7 @@ static int add_port(struct ports_device *portdev, u32 id)
port->inbuf = NULL;
port->cons.hvc = NULL;
- port->host_connected = false;
+ port->host_connected = port->guest_connected = false;
port->in_vq = portdev->in_vqs[port->id];
port->out_vq = portdev->out_vqs[port->id];