Commit f997f00b authored by Amit Shah's avatar Amit Shah Committed by Rusty Russell
Browse files

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: default avatarAmit Shah <amit.shah@redhat.com>
Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
parent 203baab8

drivers/char/virtio_console.c

+33 −17
Original line number Diff line number Diff line
@@ -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);

}



/*