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Commit d6933561 authored by Amit Shah's avatar Amit Shah Committed by Rusty Russell
Browse files

virtio: console: Fill ports' entire in_vq with buffers 



Instead of allocating just one buffer for a port's in_vq, fill
the entire in_vq with buffers so the host need not stall while
an application consumes the data and makes the buffer available
again for the host.

Signed-off-by: default avatarAmit Shah <amit.shah@redhat.com>
Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
parent 22a29eac

drivers/char/virtio_console.c

+32 −21
Original line number Diff line number Diff line
@@ -330,6 +330,7 @@ static void discard_port_data(struct port *port) 
	struct port_buffer *buf;

	struct virtqueue *vq;

	unsigned int len;

	int ret;



	vq = port->in_vq;

	if (port->inbuf)
@@ -337,16 +338,18 @@ static void discard_port_data(struct port *port) 
	else

		buf = vq->vq_ops->get_buf(vq, &len);



	if (!buf)

		return;



	ret = 0;

	while (buf) {

		if (add_inbuf(vq, buf) < 0) {

		buf->len = buf->offset = 0;

		dev_warn(port->dev, "Error adding buffer back to vq\n");

		return;

			ret++;

			free_buf(buf);

		}

		buf = vq->vq_ops->get_buf(vq, &len);

	}



	port->inbuf = NULL;

	if (ret)

		dev_warn(port->dev, "Errors adding %d buffers back to vq\n",

			 ret);

}



static bool port_has_data(struct port *port)
@@ -354,12 +357,19 @@ static bool port_has_data(struct port *port) 
	unsigned long flags;

	bool ret;



	ret = false;

	spin_lock_irqsave(&port->inbuf_lock, flags);

	if (port->inbuf)

	if (port->inbuf) {

		ret = true;

		goto out;

	}

	port->inbuf = get_inbuf(port);

	if (port->inbuf) {

		ret = true;

		goto out;

	}

	ret = false;

out:

	spin_unlock_irqrestore(&port->inbuf_lock, flags);



	return ret;

}
@@ -1011,6 +1021,7 @@ static void in_intr(struct virtqueue *vq) 
		return;



	spin_lock_irqsave(&port->inbuf_lock, flags);

	if (!port->inbuf)

		port->inbuf = get_inbuf(port);



	/*
@@ -1087,7 +1098,7 @@ static int add_port(struct ports_device *portdev, u32 id) 
{

	char debugfs_name[16];

	struct port *port;

	struct port_buffer *inbuf;

	struct port_buffer *buf;

	dev_t devt;

	int err;
@@ -1132,22 +1143,21 @@ static int add_port(struct ports_device *portdev, u32 id) 
	spin_lock_init(&port->inbuf_lock);

	init_waitqueue_head(&port->waitqueue);



	inbuf = alloc_buf(PAGE_SIZE);

	if (!inbuf) {

	/* Fill the in_vq with buffers so the host can send us data. */

	err = fill_queue(port->in_vq, &port->inbuf_lock);

	if (!err) {

		dev_err(port->dev, "Error allocating inbufs\n");

		err = -ENOMEM;

		goto free_device;

	}



	/* Register the input buffer the first time. */

	add_inbuf(port->in_vq, inbuf);



	/*

	 * If we're not using multiport support, this has to be a console port

	 */

	if (!use_multiport(port->portdev)) {

		err = init_port_console(port);

		if (err)

			goto free_inbuf;

			goto free_inbufs;

	}



	spin_lock_irq(&portdev->ports_lock);
@@ -1175,8 +1185,9 @@ static int add_port(struct ports_device *portdev, u32 id) 
	}

	return 0;



free_inbuf:

	free_buf(inbuf);

free_inbufs:

	while ((buf = port->in_vq->vq_ops->detach_unused_buf(port->in_vq)))

		free_buf(buf);

free_device:

	device_destroy(pdrvdata.class, port->dev->devt);

free_cdev: