diff options
| -rw-r--r-- | drivers/char/virtio_console.c | 50 |
1 files changed, 33 insertions, 17 deletions
diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c index 5096d92f5b8..d01051060be 100644 --- a/drivers/char/virtio_console.c +++ b/drivers/char/virtio_console.c @@ -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); } /* |