* [Qemu-devel] [PATCH v2] vhost_net: don't enable vring if backend lack this feature
@ 2016-09-23 10:04 Chen Hanxiao
2016-09-23 15:33 ` Michael S. Tsirkin
0 siblings, 1 reply; 2+ messages in thread
From: Chen Hanxiao @ 2016-09-23 10:04 UTC (permalink / raw)
To: Michael S. Tsirkin; +Cc: qemu-devel, Jason Wang, Chen Hanxiao
From: Chen Hanxiao <chenhanxiao@gmail.com>
If backend(such as dpdk) lack the feather,
don't assume it in vring_enable.
Or we may fail in vhost_net_start, then we can't use vhost.
This will bring compat issue with old version backend.
Signed-off-by: Chen Hanxiao <chenhanxiao@gmail.com>
---
v2: return 0 there if protocol features aren't negotiated.
hw/net/vhost_net.c | 12 +++++++++---
1 file changed, 9 insertions(+), 3 deletions(-)
diff --git a/hw/net/vhost_net.c b/hw/net/vhost_net.c
index f2d49ad..a1b796a 100644
--- a/hw/net/vhost_net.c
+++ b/hw/net/vhost_net.c
@@ -425,11 +425,17 @@ int vhost_set_vring_enable(NetClientState *nc, int enable)
{
VHostNetState *net = get_vhost_net(nc);
const VhostOps *vhost_ops = net->dev.vhost_ops;
-
- nc->vring_enable = enable;
+ int ret;
if (vhost_ops && vhost_ops->vhost_set_vring_enable) {
- return vhost_ops->vhost_set_vring_enable(&net->dev, enable);
+ ret = vhost_ops->vhost_set_vring_enable(&net->dev, enable);
+ /*
+ * Try to enable vring feature.
+ * If protocol features aren't negotiated, return 0 for back compat.
+ */
+ if (ret == 0) {
+ nc->vring_enable = enable;
+ }
}
return 0;
--
1.8.3.1
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [Qemu-devel] [PATCH v2] vhost_net: don't enable vring if backend lack this feature
2016-09-23 10:04 [Qemu-devel] [PATCH v2] vhost_net: don't enable vring if backend lack this feature Chen Hanxiao
@ 2016-09-23 15:33 ` Michael S. Tsirkin
0 siblings, 0 replies; 2+ messages in thread
From: Michael S. Tsirkin @ 2016-09-23 15:33 UTC (permalink / raw)
To: Chen Hanxiao; +Cc: qemu-devel, Jason Wang, Chen Hanxiao
On Fri, Sep 23, 2016 at 06:04:06PM +0800, Chen Hanxiao wrote:
> From: Chen Hanxiao <chenhanxiao@gmail.com>
>
> If backend(such as dpdk) lack the feather,
Sorry, I don't understand what does this mean.
> don't assume it in vring_enable.
> Or we may fail in vhost_net_start, then we can't use vhost.
> This will bring compat issue with old version backend.
>
> Signed-off-by: Chen Hanxiao <chenhanxiao@gmail.com>
> ---
> v2: return 0 there if protocol features aren't negotiated.
>
> hw/net/vhost_net.c | 12 +++++++++---
> 1 file changed, 9 insertions(+), 3 deletions(-)
>
> diff --git a/hw/net/vhost_net.c b/hw/net/vhost_net.c
> index f2d49ad..a1b796a 100644
> --- a/hw/net/vhost_net.c
> +++ b/hw/net/vhost_net.c
> @@ -425,11 +425,17 @@ int vhost_set_vring_enable(NetClientState *nc, int enable)
> {
> VHostNetState *net = get_vhost_net(nc);
> const VhostOps *vhost_ops = net->dev.vhost_ops;
> -
> - nc->vring_enable = enable;
> + int ret;
>
> if (vhost_ops && vhost_ops->vhost_set_vring_enable) {
> - return vhost_ops->vhost_set_vring_enable(&net->dev, enable);
> + ret = vhost_ops->vhost_set_vring_enable(&net->dev, enable);
> + /*
> + * Try to enable vring feature.
What does this mean?
> + * If protocol features aren't negotiated, return 0 for back compat.
How do you mean "for back compat"?
> + */
> + if (ret == 0) {
> + nc->vring_enable = enable;
> + }
> }
This clearly does not set vring_enable if vhost_set_vring_enable is
NULL.
>
> return 0;
> --
> 1.8.3.1
>
^ permalink raw reply [flat|nested] 2+ messages in thread
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