Commit fdb9a054 authored by Amit Shah's avatar Amit Shah Committed by Rusty Russell
Browse files

virtio: console: encapsulate buffer information in a struct 



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

Signed-off-by: default avatarAmit Shah <amit.shah@redhat.com>
Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
parent 21206ede

drivers/char/virtio_console.c

+55 −15
Original line number Diff line number Diff line
@@ -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;

}