* [PATCH 3/4] virtio: console makes incorrect assumption about virtio API
@ 2010-03-30 5:19 Rusty Russell
2010-03-30 6:30 ` Amit Shah
0 siblings, 1 reply; 2+ messages in thread
From: Rusty Russell @ 2010-03-30 5:19 UTC (permalink / raw)
To: Amit Shah; +Cc: Michael S. Tsirkin, virtualization
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 <rusty@rustcorp.com.au>
To: Amit Shah <amit.shah@redhat.com>
---
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
--- a/drivers/char/virtio_console.c
+++ b/drivers/char/virtio_console.c
@@ -415,20 +415,16 @@ static ssize_t send_buf(struct port *por
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;
}
/*
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [PATCH 3/4] virtio: console makes incorrect assumption about virtio API
2010-03-30 5:19 [PATCH 3/4] virtio: console makes incorrect assumption about virtio API Rusty Russell
@ 2010-03-30 6:30 ` Amit Shah
0 siblings, 0 replies; 2+ messages in thread
From: Amit Shah @ 2010-03-30 6:30 UTC (permalink / raw)
To: Rusty Russell; +Cc: Michael S. Tsirkin, virtualization
On (Tue) Mar 30 2010 [15:49:22], Rusty Russell wrote:
> 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 <rusty@rustcorp.com.au>
> To: Amit Shah <amit.shah@redhat.com>
Acked-by: Amit Shah <amit.shah@redhat.com>
> ---
> 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
> --- a/drivers/char/virtio_console.c
> +++ b/drivers/char/virtio_console.c
> @@ -415,20 +415,16 @@ static ssize_t send_buf(struct port *por
> 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;
> }
>
> /*
>
Amit
--
http://log.amitshah.net/
^ permalink raw reply [flat|nested] 2+ messages in thread
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