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Commit 3eae0ade authored by Amit Shah's avatar Amit Shah Committed by Rusty Russell
Browse files

virtio: console: Send SIGIO to processes that request it for host events 



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: default avatarAmit Shah <amit.shah@redhat.com>
Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
parent e062013c

drivers/char/virtio_console.c

+25 −0
Original line number Diff line number Diff line
@@ -196,6 +196,9 @@ 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;
@@ -815,6 +818,14 @@ static int port_fops_open(struct inode *inode, struct file *filp) 
	return ret;

}



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
@@ -828,6 +839,7 @@ static const struct file_operations port_fops = { 
	.write = port_fops_write,

	.poll  = port_fops_poll,

	.release = port_fops_release,

	.fasync = port_fops_fasync,

};



/*
@@ -1086,6 +1098,12 @@ static unsigned int fill_queue(struct virtqueue *vq, spinlock_t *lock) 
	return nr_added_bufs;

}



static void send_sigio_to_port(struct port *port)

{

	if (port->async_queue && port->guest_connected)

		kill_fasync(&port->async_queue, SIGIO, POLL_OUT);

}



static int add_port(struct ports_device *portdev, u32 id)

{

	char debugfs_name[16];
@@ -1108,6 +1126,7 @@ 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;
@@ -1362,6 +1381,12 @@ 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.

		 */

		send_sigio_to_port(port);

		break;

	case VIRTIO_CONSOLE_PORT_NAME:

		/*