lguest: fix writev returning short on console output

I've never seen it here, but I can't find anywhere that says writev
will write everything.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

1 files changed, 6 insertions, 1 deletions

diff --git a/Documentation/lguest/lguest.c b/Documentation/lguest/lguest.c
index 8704600c5e42..02fa524cf4ad 100644
--- a/Documentation/lguest/lguest.c
+++ b/Documentation/lguest/lguest.c
@@ -836,7 +836,12 @@ static void handle_console_output(struct virtqueue *vq, bool timeout)
         while ((head = get_vq_desc(vq, iov, &out, &in)) != vq->vring.num) {
                 if (in)
                         errx(1, "Input buffers in output queue?");
-                writev(STDOUT_FILENO, iov, out);
+                while (!iov_empty(iov, out)) {
+                        int len = writev(STDOUT_FILENO, iov, out);
+                        if (len <= 0)
+                                err(1, "Write to stdout gave %i", len);
+                        iov_consume(iov, out, len);
+                }
                 add_used_and_trigger(vq, head, 0);
         }
 }