From 9ff4cfab82d27e9fda72315f911bbaa9516e04bc Mon Sep 17 00:00:00 2001 From: Rusty Russell Date: Thu, 8 Apr 2010 09:46:16 -0600 Subject: [PATCH] virtio: console makes incorrect assumption about virtio API The get_buf() API sets the second arg to the number of bytes *written* by the other side; in this case it should be zero as these are output buffers. lguest gets this right (obviously kvm's console doesn't), resulting in continual buildup of console writes. Signed-off-by: Rusty Russell Acked-by: Amit Shah --- drivers/char/virtio_console.c | 10 +++------- 1 file changed, 3 insertions(+), 7 deletions(-) diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c index 48306bc733f7..86e9011325dc 100644 --- a/drivers/char/virtio_console.c +++ b/drivers/char/virtio_console.c @@ -416,20 +416,16 @@ static ssize_t send_buf(struct port *port, void *in_buf, size_t in_count) out_vq->vq_ops->kick(out_vq); if (ret < 0) { - len = 0; + in_count = 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. - */ + /* Wait till the host acknowledges it pushed out the data we sent. */ 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; + return in_count; } /* -- 2.39.5