Re: [PATCH 1/2] vhost-user: Refactor vhost acked features saving

[Hyman Huang]

在 2022/10/7 22:01, Michael S. Tsirkin 写道:
> On Mon, Sep 26, 2022 at 02:36:40PM +0800, huangy81@chinatelecom.cn wrote:
> > From: Hyman Huang(黄勇) <huangy81@chinatelecom.cn>
> >
> > Abstract vhost acked features saving into
> > vhost_user_save_acked_features, export it as util function.
> >
> > Signed-off-by: Hyman Huang(黄勇) <huangy81@chinatelecom.cn>
> > Signed-off-by: Guoyi Tu <tugy@chinatelecom.cn>
> > ---
> >   include/net/vhost-user.h |  2 ++
> >   net/vhost-user.c         | 35 +++++++++++++++++++----------------
> >   2 files changed, 21 insertions(+), 16 deletions(-)
> >
> > diff --git a/include/net/vhost-user.h b/include/net/vhost-user.h
> > index 5bcd8a6285..00d46613d3 100644
> > --- a/include/net/vhost-user.h
> > +++ b/include/net/vhost-user.h
> > @@ -14,5 +14,7 @@
> >   struct vhost_net;
> >   struct vhost_net *vhost_user_get_vhost_net(NetClientState *nc);
> >   uint64_t vhost_user_get_acked_features(NetClientState *nc);
> > +void vhost_user_save_acked_features(NetClientState *nc,
> > +                                    bool cleanup);
> >   
> >   #endif /* VHOST_USER_H */
> > diff --git a/net/vhost-user.c b/net/vhost-user.c
> > index b1a0247b59..c512cc9727 100644
> > --- a/net/vhost-user.c
> > +++ b/net/vhost-user.c
> > @@ -45,24 +45,31 @@ uint64_t vhost_user_get_acked_features(NetClientState *nc)
> >       return s->acked_features;
> >   }
> >   
> > -static void vhost_user_stop(int queues, NetClientState *ncs[])
> > +void vhost_user_save_acked_features(NetClientState *nc, bool cleanup)
> >   {
> >       NetVhostUserState *s;
> > +
> > +    s = DO_UPCAST(NetVhostUserState, nc, nc);
> > +    if (s->vhost_net) {
> > +        uint64_t features = vhost_net_get_acked_features(s->vhost_net);
> > +        if (features) {
> > +            s->acked_features = features;
> > +        }
>
> Note it does not set  acked_features if features are 0.
> Which might be the case for legacy ...
> I will need to analyze this more to figure out what's
> the correct behaviour....
Thanks Michael for commentting. :)

Indeed, backing up acked_features in the two functions chr_closed_bh() 
vhost_user_stop() are kind of different as above, it also seems a little 
weried for me.

IMHO, we can always keep the acked_features in NetVhostUserState the 
same as acked_features in vhost_dev no matter what features are, since 
this is the role that acked_features in NetVhostUserState plays and we 
can just focus on the validation of acked_features in vhost_dev if 
something goes wrong.

Thanks,
Yong

> Stefano? Raphael?
>
> > +
> > +        if (cleanup) {
> > +            vhost_net_cleanup(s->vhost_net);
> > +        }
> > +    }
> > +}
> > +
> > +static void vhost_user_stop(int queues, NetClientState *ncs[])
> > +{
> >       int i;
> >   
> >       for (i = 0; i < queues; i++) {
> >           assert(ncs[i]->info->type == NET_CLIENT_DRIVER_VHOST_USER);
> >   
> > -        s = DO_UPCAST(NetVhostUserState, nc, ncs[i]);
> > -
> > -        if (s->vhost_net) {
> > -            /* save acked features */
> > -            uint64_t features = vhost_net_get_acked_features(s->vhost_net);
> > -            if (features) {
> > -                s->acked_features = features;
> > -            }
> > -            vhost_net_cleanup(s->vhost_net);
> > -        }
> > +        vhost_user_save_acked_features(ncs[i], true);
> >       }
> >   }
> >   
> > @@ -251,11 +258,7 @@ static void chr_closed_bh(void *opaque)
> >       s = DO_UPCAST(NetVhostUserState, nc, ncs[0]);
> >   
> >       for (i = queues -1; i >= 0; i--) {
> > -        s = DO_UPCAST(NetVhostUserState, nc, ncs[i]);
> > -
> > -        if (s->vhost_net) {
> > -            s->acked_features = vhost_net_get_acked_features(s->vhost_net);
> > -        }
> > +        vhost_user_save_acked_features(ncs[i], false);
> >       }
> >   
> >       qmp_set_link(name, false, &err);
> > --
> > 2.27.0

--
Best regard

Hyman Huang(黄勇)