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 <[email protected]> --- drivers/char/virtio_console.c | 17 ++++++++++++++++- 1 files changed, 16 insertions(+), 1 deletions(-) diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c index c949e6c..abab15f 100644 --- a/drivers/char/virtio_console.c +++ b/drivers/char/virtio_console.c @@ -181,6 +181,9 @@ 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. */ @@ -565,6 +568,8 @@ 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; } @@ -583,6 +588,15 @@ 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); @@ -746,6 +760,7 @@ 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; return 0; } @@ -889,7 +904,7 @@ 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]; -- 1.6.2.5 _______________________________________________ Virtualization mailing list [email protected] https://lists.linux-foundation.org/mailman/listinfo/virtualization
