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virtio: console: encapsulate buffer information in a struct 

Collect port buffer, used_len, offset fields into a single structure.

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 19:15:01 +05:30 committed by Rusty Russell
parent 21206ede88
commit fdb9a05455
1 changed files with 55 additions and 15 deletions
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70
drivers/char/virtio_console.c
View File

@ -21,12 +21,24 @@
#include <linux/virtio_console.h>
#include "hvc_console.h"
struct port_buffer {
char *buf;
/* size of the buffer in *buf above */
size_t size;
/* used length of the buffer */
size_t len;
/* offset in the buf from which to consume data */
size_t offset;
};
struct port {
struct virtqueue *in_vq, *out_vq;
struct virtio_device *vdev;
/* This is our input buffer, and how much data is left in it. */
char *inbuf;
unsigned int used_len, offset;
/* The current buffer from which data has to be fed to readers */
struct port_buffer *inbuf;
/* The hvc device */
struct hvc_struct *hvc;
@ -38,6 +50,33 @@ static struct port console;
/* This is the very early arch-specified put chars function. */
static int (*early_put_chars)(u32, const char *, int);
static void free_buf(struct port_buffer *buf)
{
kfree(buf->buf);
kfree(buf);
}
static struct port_buffer *alloc_buf(size_t buf_size)
{
struct port_buffer *buf;
buf = kmalloc(sizeof(*buf), GFP_KERNEL);
if (!buf)
goto fail;
buf->buf = kzalloc(buf_size, GFP_KERNEL);
if (!buf->buf)
goto free_buf;
buf->len = 0;
buf->offset = 0;
buf->size = buf_size;
return buf;
free_buf:
kfree(buf);
fail:
return NULL;
}
/*
* The put_chars() callback is pretty straightforward.
*
@ -79,7 +118,7 @@ static int put_chars(u32 vtermno, const char *buf, int count)
static void add_inbuf(struct port *port)
{
struct scatterlist sg[1];
sg_init_one(sg, port->inbuf, PAGE_SIZE);
sg_init_one(sg, port->inbuf->buf, PAGE_SIZE);
/* Should always be able to add one buffer to an empty queue. */
if (port->in_vq->vq_ops->add_buf(port->in_vq, sg, 0, 1, port) < 0)
@ -98,6 +137,7 @@ static void add_inbuf(struct port *port)
static int get_chars(u32 vtermno, char *buf, int count)
{
struct port *port;
unsigned int len;
port = &console;
@ -105,22 +145,23 @@ static int get_chars(u32 vtermno, char *buf, int count)
BUG_ON(!port->in_vq);
/* No more in buffer? See if they've (re)used it. */
if (port->offset == port->used_len) {
if (!port->in_vq->vq_ops->get_buf(port->in_vq, &port->used_len))
if (port->inbuf->offset == port->inbuf->len) {
if (!port->in_vq->vq_ops->get_buf(port->in_vq, &len))
return 0;
port->offset = 0;
port->inbuf->offset = 0;
port->inbuf->len = len;
}
/* You want more than we have to give? Well, try wanting less! */
if (port->offset + count > port->used_len)
count = port->used_len - port->offset;
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 + port->offset, count);
port->offset += count;
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->offset == port->used_len)
if (port->inbuf->offset == port->inbuf->len)
add_inbuf(port);
return count;
@ -220,8 +261,7 @@ static int __devinit virtcons_probe(struct virtio_device *vdev)
port->vdev = vdev;
/* This is the scratch page we use to receive console input */
port->used_len = 0;
port->inbuf = kmalloc(PAGE_SIZE, GFP_KERNEL);
port->inbuf = alloc_buf(PAGE_SIZE);
if (!port->inbuf) {
err = -ENOMEM;
goto fail;
@ -263,7 +303,7 @@ static int __devinit virtcons_probe(struct virtio_device *vdev)
free_vqs:
vdev->config->del_vqs(vdev);
free:
kfree(port->inbuf);
free_buf(port->inbuf);
fail:
return err;
}