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: Amit Shah <amit.shah@redhat.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
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@ -196,6 +196,9 @@ struct port {
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/* The 'name' of the port that we expose via sysfs properties */
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char *name;
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/* We can notify apps of host connect / disconnect events via SIGIO */
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struct fasync_struct *async_queue;
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/* The 'id' to identify the port with the Host */
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u32 id;
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@ -815,6 +818,14 @@ static int port_fops_open(struct inode *inode, struct file *filp)
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return ret;
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}
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static int port_fops_fasync(int fd, struct file *filp, int mode)
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{
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struct port *port;
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port = filp->private_data;
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return fasync_helper(fd, filp, mode, &port->async_queue);
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}
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/*
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* The file operations that we support: programs in the guest can open
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* a console device, read from it, write to it, poll for data and
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@ -828,6 +839,7 @@ static const struct file_operations port_fops = {
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.write = port_fops_write,
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.poll = port_fops_poll,
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.release = port_fops_release,
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.fasync = port_fops_fasync,
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};
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/*
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@ -1086,6 +1098,12 @@ static unsigned int fill_queue(struct virtqueue *vq, spinlock_t *lock)
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return nr_added_bufs;
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}
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static void send_sigio_to_port(struct port *port)
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{
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if (port->async_queue && port->guest_connected)
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kill_fasync(&port->async_queue, SIGIO, POLL_OUT);
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}
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static int add_port(struct ports_device *portdev, u32 id)
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{
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char debugfs_name[16];
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@ -1108,6 +1126,7 @@ static int add_port(struct ports_device *portdev, u32 id)
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port->name = NULL;
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port->inbuf = NULL;
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port->cons.hvc = NULL;
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port->async_queue = NULL;
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port->cons.ws.ws_row = port->cons.ws.ws_col = 0;
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@ -1362,6 +1381,12 @@ static void handle_control_message(struct ports_device *portdev,
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spin_lock_irq(&port->outvq_lock);
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reclaim_consumed_buffers(port);
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spin_unlock_irq(&port->outvq_lock);
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/*
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* If the guest is connected, it'll be interested in
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* knowing the host connection state changed.
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*/
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send_sigio_to_port(port);
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break;
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case VIRTIO_CONSOLE_PORT_NAME:
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/*
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