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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: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Amit Shah 2010-02-12 10:32:18 +05:30 committed by Rusty Russell
parent 22a29eacd2
commit d693356192
1 changed files with 32 additions and 21 deletions
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53
drivers/char/virtio_console.c
View File

@ -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;
if (add_inbuf(vq, buf) < 0) {
buf->len = buf->offset = 0;
dev_warn(port->dev, "Error adding buffer back to vq\n");
return;
ret = 0;
while (buf) {
if (add_inbuf(vq, buf) < 0) {
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;
}
@ -1011,7 +1021,8 @@ static void in_intr(struct virtqueue *vq)
return;
spin_lock_irqsave(&port->inbuf_lock, flags);
port->inbuf = get_inbuf(port);
if (!port->inbuf)
port->inbuf = get_inbuf(port);
/*
* Don't queue up data when port is closed. This condition
@ -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: