linux-kernel - Re: [PATCH net-next v2 3/3] bridge: Extend br_fill

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Date:   Wed, 1 Jul 2020 15:19:39 +0200
From:   Horatiu Vultur <horatiu.vultur@...rochip.com>
To:     Nikolay Aleksandrov <nikolay@...ulusnetworks.com>
CC:     <roopa@...ulusnetworks.com>, <davem@...emloft.net>,
        <kuba@...nel.org>, <jiri@...lanox.com>, <netdev@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>,
        <bridge@...ts.linux-foundation.org>, <UNGLinuxDriver@...rochip.com>
Subject: Re: [PATCH net-next v2 3/3] bridge: Extend br_fill_ifinfo to return
 MPR status

The 07/01/2020 12:51, Nikolay Aleksandrov wrote:
> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
> 
> On 01/07/2020 10:22, Horatiu Vultur wrote:
> > This patch extends the function br_fill_ifinfo to return also the MRP
> > status for each instance on a bridge. It also adds a new filter
> > RTEXT_FILTER_MRP to return the MRP status only when this is set, not to
> > interfer with the vlans. The MRP status is return only on the bridge
> > interfaces.
> >
> > Signed-off-by: Horatiu Vultur <horatiu.vultur@...rochip.com>
> > ---
> >  include/uapi/linux/rtnetlink.h |  1 +
> >  net/bridge/br_netlink.c        | 29 ++++++++++++++++++++++++++++-
> >  2 files changed, 29 insertions(+), 1 deletion(-)
> >
> > diff --git a/include/uapi/linux/rtnetlink.h b/include/uapi/linux/rtnetlink.h
> > index 879e64950a0a2..9b814c92de123 100644
> > --- a/include/uapi/linux/rtnetlink.h
> > +++ b/include/uapi/linux/rtnetlink.h
> > @@ -778,6 +778,7 @@ enum {
> >  #define RTEXT_FILTER_BRVLAN  (1 << 1)
> >  #define RTEXT_FILTER_BRVLAN_COMPRESSED       (1 << 2)
> >  #define      RTEXT_FILTER_SKIP_STATS (1 << 3)
> > +#define RTEXT_FILTER_MRP     (1 << 4)
> >
> >  /* End of information exported to user level */
> >
> > diff --git a/net/bridge/br_netlink.c b/net/bridge/br_netlink.c
> > index 240e260e3461c..6ecb7c7453dcb 100644
> > --- a/net/bridge/br_netlink.c
> > +++ b/net/bridge/br_netlink.c
> > @@ -453,6 +453,32 @@ static int br_fill_ifinfo(struct sk_buff *skb,
> >               rcu_read_unlock();
> >               if (err)
> >                       goto nla_put_failure;
> > +
> > +             nla_nest_end(skb, af);
> > +     }
> > +
> > +     if (filter_mask & RTEXT_FILTER_MRP) {
> > +             struct nlattr *af;
> > +             int err;
> > +
> > +             /* RCU needed because of the VLAN locking rules (rcu || rtnl) */
> > +             rcu_read_lock();

Hi Nik,
> 
> If you're using RCU, then in the previous patch (02) you should be using RCU primitives
> to walk the list and deref the ports.
> Alternatively if you rely on rtnl only then drop these RCU locks here as they're misleading.
> 
> I'd prefer to just use RCU for it in case we drop rtnl one day when dumping.

Thanks for the comments. I will create a new series where I will use the
RCU.

> 
> > +             if (!br_mrp_enabled(br) || port) {
> > +                     rcu_read_unlock();
> > +                     goto done;
> > +             }
> > +             af = nla_nest_start_noflag(skb, IFLA_AF_SPEC);
> > +             if (!af) {
> > +                     rcu_read_unlock();
> > +                     goto nla_put_failure;
> > +             }
> > +
> > +             err = br_mrp_fill_info(skb, br);
> > +
> > +             rcu_read_unlock();
> > +             if (err)
> > +                     goto nla_put_failure;
> > +
> >               nla_nest_end(skb, af);
> >       }
> >
> > @@ -516,7 +542,8 @@ int br_getlink(struct sk_buff *skb, u32 pid, u32 seq,
> >       struct net_bridge_port *port = br_port_get_rtnl(dev);
> >
> >       if (!port && !(filter_mask & RTEXT_FILTER_BRVLAN) &&
> > -         !(filter_mask & RTEXT_FILTER_BRVLAN_COMPRESSED))
> > +         !(filter_mask & RTEXT_FILTER_BRVLAN_COMPRESSED) &&
> > +         !(filter_mask & RTEXT_FILTER_MRP))
> >               return 0;
> >
> >       return br_fill_ifinfo(skb, port, pid, seq, RTM_NEWLINK, nlflags,
> >
> 

-- 
/Horatiu