A process can request for SIGIO on host connect / disconnect events using the O_ASYNC file flag using fcntl().
If that's requested, and if the guest-side connection for the port is open, any host-side open/close events for that port will raise a SIGIO. The process can then use poll() within the signal handler to find out which port triggered the signal. Signed-off-by: Amit Shah <[email protected]> --- drivers/char/virtio_console.c | 20 ++++++++++++++++++++ 1 files changed, 20 insertions(+), 0 deletions(-) diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c index a34f40e..b74d097 100644 --- a/drivers/char/virtio_console.c +++ b/drivers/char/virtio_console.c @@ -187,6 +187,9 @@ struct port { /* The 'name' of the port that we expose via sysfs properties */ char *name; + /* We can notify apps of host connect / disconnect events via SIGIO */ + struct fasync_struct *async_queue; + /* The 'id' to identify the port with the Host */ u32 id; @@ -719,6 +722,14 @@ static int port_fops_open(struct inode *inode, struct file *filp) return 0; } +static int port_fops_fasync(int fd, struct file *filp, int mode) +{ + struct port *port; + + port = filp->private_data; + return fasync_helper(fd, filp, mode, &port->async_queue); +} + /* * 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 @@ -732,6 +743,7 @@ static const struct file_operations port_fops = { .write = port_fops_write, .poll = port_fops_poll, .release = port_fops_release, + .fasync = port_fops_fasync, }; /* @@ -1011,6 +1023,7 @@ static int add_port(struct ports_device *portdev, u32 id) port->name = NULL; port->inbuf = NULL; port->cons.hvc = NULL; + port->async_queue = NULL; port->cons.ws.ws_row = port->cons.ws.ws_col = 0; @@ -1234,6 +1247,13 @@ static void handle_control_message(struct ports_device *portdev, spin_lock_irq(&port->outvq_lock); reclaim_consumed_buffers(port); spin_unlock_irq(&port->outvq_lock); + + /* + * If the guest is connected, it'll be interested in + * knowing the host connection state changed. + */ + if (port->async_queue && port->guest_connected) + kill_fasync(&port->async_queue, SIGIO, POLL_OUT); break; case VIRTIO_CONSOLE_PORT_NAME: /* -- 1.7.2.2 _______________________________________________ Virtualization mailing list [email protected] https://lists.linux-foundation.org/mailman/listinfo/virtualization
