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virtio: console: Introduce function to hand off data from host to readers

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In preparation for serving data to userspace (generic ports) as well as
in-kernel users (hvc consoles), separate out the functionality common to
both in a 'fill_readbuf()' function.

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 2010-01-18 19:15:12 +05:30 committed by Rusty Russell
parent 2658a79acf
commit 203baab8ba
1 changed files with 106 additions and 36 deletions
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142
drivers/char/virtio_console.c
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@ -100,6 +100,13 @@ struct port {
/* The current buffer from which data has to be fed to readers */
struct port_buffer *inbuf;
/*
* To protect the operations on the in_vq associated with this
* port. Has to be a spinlock because it can be called from
* interrupt context (get_char()).
*/
spinlock_t inbuf_lock;
/* The IO vqs for this port */
struct virtqueue *in_vq, *out_vq;
@ -132,6 +139,25 @@ out:
return port;
}
static struct port *find_port_by_vq(struct ports_device *portdev,
struct virtqueue *vq)
{
struct port *port;
struct console *cons;
unsigned long flags;
spin_lock_irqsave(&pdrvdata_lock, flags);
list_for_each_entry(cons, &pdrvdata.consoles, list) {
port = container_of(cons, struct port, cons);
if (port->in_vq == vq || port->out_vq == vq)
goto out;
}
port = NULL;
out:
spin_unlock_irqrestore(&pdrvdata_lock, flags);
return port;
}
static void free_buf(struct port_buffer *buf)
{
kfree(buf->buf);
@ -181,15 +207,67 @@ static void *get_inbuf(struct port *port)
*
* Callers should take appropriate locks.
*/
static void add_inbuf(struct virtqueue *vq, struct port_buffer *buf)
static int add_inbuf(struct virtqueue *vq, struct port_buffer *buf)
{
struct scatterlist sg[1];
int ret;
sg_init_one(sg, buf->buf, buf->size);
if (vq->vq_ops->add_buf(vq, sg, 0, 1, buf) < 0)
BUG();
ret = vq->vq_ops->add_buf(vq, sg, 0, 1, buf);
vq->vq_ops->kick(vq);
return ret;
}
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)
ret = true;
spin_unlock_irqrestore(&port->inbuf_lock, flags);
return ret;
}
/*
* Give out the data that's requested from the buffer that we have
* queued up.
*/
static ssize_t fill_readbuf(struct port *port, char *out_buf, size_t out_count)
{
struct port_buffer *buf;
unsigned long flags;
if (!out_count || !port_has_data(port))
return 0;
buf = port->inbuf;
if (out_count > buf->len - buf->offset)
out_count = buf->len - buf->offset;
memcpy(out_buf, buf->buf + buf->offset, out_count);
/* Return the number of bytes actually copied */
buf->offset += out_count;
if (buf->offset == buf->len) {
/*
* We're done using all the data in this buffer.
* Re-queue so that the Host can send us more data.
*/
spin_lock_irqsave(&port->inbuf_lock, flags);
port->inbuf = NULL;
if (add_inbuf(port->in_vq, buf) < 0)
dev_warn(&port->portdev->vdev->dev, "failed add_buf\n");
spin_unlock_irqrestore(&port->inbuf_lock, flags);
}
return out_count;
}
/*
@ -234,9 +312,8 @@ static int put_chars(u32 vtermno, const char *buf, int count)
* get_chars() is the callback from the hvc_console infrastructure
* when an interrupt is received.
*
* Most of the code deals with the fact that the hvc_console()
* infrastructure only asks us for 16 bytes at a time. We keep
* in_offset and in_used fields for partially-filled buffers.
* We call out to fill_readbuf that gets us the required data from the
* buffers that are queued up.
*/
static int get_chars(u32 vtermno, char *buf, int count)
{
@ -249,25 +326,7 @@ static int get_chars(u32 vtermno, char *buf, int count)
/* If we don't have an input queue yet, we can't get input. */
BUG_ON(!port->in_vq);
/* No more in buffer? See if they've (re)used it. */
if (port->inbuf->offset == port->inbuf->len) {
if (!get_inbuf(port))
return 0;
}
/* You want more than we have to give? Well, try wanting less! */
if (port->inbuf->offset + count > port->inbuf->len)
count = port->inbuf->len - port->inbuf->offset;
/* Copy across to their buffer and increment offset. */
memcpy(buf, port->inbuf->buf + port->inbuf->offset, count);
port->inbuf->offset += count;
/* Finished? Re-register buffer so Host will use it again. */
if (port->inbuf->offset == port->inbuf->len)
add_inbuf(port->in_vq, port->inbuf);
return count;
return fill_readbuf(port, buf, count);
}
static void resize_console(struct port *port)
@ -314,13 +373,18 @@ static void notifier_del_vio(struct hvc_struct *hp, int data)
static void hvc_handle_input(struct virtqueue *vq)
{
struct console *cons;
bool activity = false;
struct port *port;
unsigned long flags;
list_for_each_entry(cons, &pdrvdata.consoles, list)
activity |= hvc_poll(cons->hvc);
port = find_port_by_vq(vq->vdev->priv, vq);
if (!port)
return;
if (activity)
spin_lock_irqsave(&port->inbuf_lock, flags);
port->inbuf = get_inbuf(port);
spin_unlock_irqrestore(&port->inbuf_lock, flags);
if (hvc_poll(port->cons.hvc))
hvc_kick();
}
@ -388,6 +452,7 @@ int __devinit init_port_console(struct port *port)
static int __devinit add_port(struct ports_device *portdev)
{
struct port *port;
struct port_buffer *inbuf;
int err;
port = kmalloc(sizeof(*port), GFP_KERNEL);
@ -397,26 +462,31 @@ static int __devinit add_port(struct ports_device *portdev)
}
port->portdev = portdev;
port->inbuf = NULL;
port->in_vq = portdev->in_vqs[0];
port->out_vq = portdev->out_vqs[0];
port->inbuf = alloc_buf(PAGE_SIZE);
if (!port->inbuf) {
spin_lock_init(&port->inbuf_lock);
inbuf = alloc_buf(PAGE_SIZE);
if (!inbuf) {
err = -ENOMEM;
goto free_port;
}
/* Register the input buffer the first time. */
add_inbuf(port->in_vq, inbuf);
err = init_port_console(port);
if (err)
goto free_inbuf;
/* Register the input buffer the first time. */
add_inbuf(port->in_vq, port->inbuf);
return 0;
free_inbuf:
free_buf(port->inbuf);
free_buf(inbuf);
free_port:
kfree(port);
fail: