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virtio: console: Introduce a send_buf function for a common path for sending data to host 

Adding support for generic ports that will write to userspace will need
some code changes.

Consolidate the write routine into send_buf() and put_chars() now just
calls into the new 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 2009-12-21 17:28:51 +05:30 committed by Rusty Russell
parent 203baab8ba
commit f997f00bf8
1 changed files with 33 additions and 17 deletions
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50
drivers/char/virtio_console.c
View File

@ -233,6 +233,38 @@ static bool port_has_data(struct port *port)
return ret;
}
static ssize_t send_buf(struct port *port, void *in_buf, size_t in_count)
{
struct scatterlist sg[1];
struct virtqueue *out_vq;
ssize_t ret;
unsigned int len;
out_vq = port->out_vq;
sg_init_one(sg, in_buf, in_count);
ret = out_vq->vq_ops->add_buf(out_vq, sg, 1, 0, in_buf);
/* Tell Host to go! */
out_vq->vq_ops->kick(out_vq);
if (ret < 0) {
len = 0;
goto fail;
}
/*
* Wait till the host acknowledges it pushed out the data we
* sent. Also ensure we return to userspace the number of
* bytes that were successfully consumed by the host.
*/
while (!out_vq->vq_ops->get_buf(out_vq, &len))
cpu_relax();
fail:
/* We're expected to return the amount of data we wrote */
return len;
}
/*
* Give out the data that's requested from the buffer that we have
* queued up.
@ -280,10 +312,7 @@ static ssize_t fill_readbuf(struct port *port, char *out_buf, size_t out_count)
*/
static int put_chars(u32 vtermno, const char *buf, int count)
{
struct scatterlist sg[1];
struct port *port;
struct virtqueue *out_vq;
unsigned int len;
port = find_port_by_vtermno(vtermno);
if (!port)
@ -292,20 +321,7 @@ static int put_chars(u32 vtermno, const char *buf, int count)
if (unlikely(early_put_chars))
return early_put_chars(vtermno, buf, count);
out_vq = port->out_vq;
/* This is a convenient routine to initialize a single-elem sg list */
sg_init_one(sg, buf, count);
/* This shouldn't fail: if it does, we lose chars. */
if (out_vq->vq_ops->add_buf(out_vq, sg, 1, 0, port) >= 0) {
/* Tell Host to go! */
out_vq->vq_ops->kick(out_vq);
while (!out_vq->vq_ops->get_buf(out_vq, &len))
cpu_relax();
}
/* We're expected to return the amount of data we wrote: all of it. */
return count;
return send_buf(port, (void *)buf, count);
}
/*