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Commit b766ceed authored by Amit Shah's avatar Amit Shah Committed by Rusty Russell
Browse files

virtio: console: Prepare for writing to userspace buffers 



When ports get advertised as char devices, the buffers will come from
userspace. Equip the fill_readbuf function with the ability to write
to userspace buffers.

Signed-off-by: default avatarAmit Shah <amit.shah@redhat.com>
Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
parent 17634ba2

drivers/char/virtio_console.c

+14 −6
Original line number Diff line number Diff line
@@ -358,7 +358,8 @@ static ssize_t send_buf(struct port *port, void *in_buf, size_t in_count) 
 * 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)

static ssize_t fill_readbuf(struct port *port, char *out_buf, size_t out_count,

			    bool to_user)

{

	struct port_buffer *buf;

	unsigned long flags;
@@ -367,12 +368,18 @@ static ssize_t fill_readbuf(struct port *port, char *out_buf, size_t out_count) 
		return 0;



	buf = port->inbuf;

	if (out_count > buf->len - buf->offset)

		out_count = buf->len - buf->offset;

	out_count = min(out_count, buf->len - buf->offset);



	if (to_user) {

		ssize_t ret;



		ret = copy_to_user(out_buf, buf->buf + buf->offset, out_count);

		if (ret)

			return -EFAULT;

	} else {

		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) {
@@ -388,6 +395,7 @@ static ssize_t fill_readbuf(struct port *port, char *out_buf, size_t out_count) 


		spin_unlock_irqrestore(&port->inbuf_lock, flags);

	}

	/* Return the number of bytes actually copied */

	return out_count;

}
@@ -431,7 +439,7 @@ 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);



	return fill_readbuf(port, buf, count);

	return fill_readbuf(port, buf, count, false);

}



static void resize_console(struct port *port)