netdev - Re: [PATCH net 1/2] ipv6: add ipv6_dev

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Date:   Thu, 6 Aug 2020 16:55:15 +0800
From:   Xin Long <lucien.xin@...il.com>
To:     Hideaki Yoshifuji <hideaki.yoshifuji@...aclelinux.com>,
        David Ahern <dsahern@...il.com>
Cc:     network dev <netdev@...r.kernel.org>, davem <davem@...emloft.net>,
        Jon Maloy <jon.maloy@...csson.com>,
        Ying Xue <ying.xue@...driver.com>,
        tipc-discussion@...ts.sourceforge.net,
        Alexey Kuznetsov <kuznet@....inr.ac.ru>,
        Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>
Subject: Re: [PATCH net 1/2] ipv6: add ipv6_dev_find()

On Thu, Aug 6, 2020 at 10:50 AM Hideaki Yoshifuji
<hideaki.yoshifuji@...aclelinux.com> wrote:
>
> Hi,
>
> 2020年8月4日(火) 0:35 Xin Long <lucien.xin@...il.com>:
> >
> > This is to add an ip_dev_find like function for ipv6, used to find
> > the dev by saddr.
> >
> > It will be used by TIPC protocol. So also export it.
> >
> > Signed-off-by: Xin Long <lucien.xin@...il.com>
> > ---
> >  include/net/addrconf.h |  2 ++
> >  net/ipv6/addrconf.c    | 39 +++++++++++++++++++++++++++++++++++++++
> >  2 files changed, 41 insertions(+)
> >
> > diff --git a/include/net/addrconf.h b/include/net/addrconf.h
> > index 8418b7d..ba3f6c15 100644
> > --- a/include/net/addrconf.h
> > +++ b/include/net/addrconf.h
> > @@ -97,6 +97,8 @@ bool ipv6_chk_custom_prefix(const struct in6_addr *addr,
> >
> >  int ipv6_chk_prefix(const struct in6_addr *addr, struct net_device *dev);
> >
> > +struct net_device *ipv6_dev_find(struct net *net, const struct in6_addr *addr);
> > +
>
> How do we handle link-local addresses?
This is what "if (!result)" branch meant to do:

+       if (!result) {
+               struct rt6_info *rt;
+
+               rt = rt6_lookup(net, addr, NULL, 0, NULL, 0);
+               if (rt) {
+                       dev = rt->dst.dev;
+                       ip6_rt_put(rt);
+               }
+       } else {
+               dev = result->idev->dev;
+       }

Thanks.

>
> --yoshfuji
>
> >  struct inet6_ifaddr *ipv6_get_ifaddr(struct net *net,
> >                                      const struct in6_addr *addr,
> >                                      struct net_device *dev, int strict);
> > diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
> > index 840bfdb..857d6f9 100644
> > --- a/net/ipv6/addrconf.c
> > +++ b/net/ipv6/addrconf.c
> > @@ -1983,6 +1983,45 @@ int ipv6_chk_prefix(const struct in6_addr *addr, struct net_device *dev)
> >  }
> >  EXPORT_SYMBOL(ipv6_chk_prefix);
> >
> > +/**
> > + * ipv6_dev_find - find the first device with a given source address.
> > + * @net: the net namespace
> > + * @addr: the source address
> > + *
> > + * The caller should be protected by RCU, or RTNL.
> > + */
> > +struct net_device *ipv6_dev_find(struct net *net, const struct in6_addr *addr)
> > +{
> > +       unsigned int hash = inet6_addr_hash(net, addr);
> > +       struct inet6_ifaddr *ifp, *result = NULL;
> > +       struct net_device *dev = NULL;
> > +
> > +       rcu_read_lock();
> > +       hlist_for_each_entry_rcu(ifp, &inet6_addr_lst[hash], addr_lst) {
> > +               if (net_eq(dev_net(ifp->idev->dev), net) &&
> > +                   ipv6_addr_equal(&ifp->addr, addr)) {
> > +                       result = ifp;
> > +                       break;
> > +               }
> > +       }
> > +
> > +       if (!result) {
> > +               struct rt6_info *rt;
> > +
> > +               rt = rt6_lookup(net, addr, NULL, 0, NULL, 0);
> > +               if (rt) {
> > +                       dev = rt->dst.dev;
> > +                       ip6_rt_put(rt);
> > +               }
> > +       } else {
> > +               dev = result->idev->dev;
> > +       }
> > +       rcu_read_unlock();
> > +
> > +       return dev;
> > +}
> > +EXPORT_SYMBOL(ipv6_dev_find);
> > +
> >  struct inet6_ifaddr *ipv6_get_ifaddr(struct net *net, const struct in6_addr *addr,
> >                                      struct net_device *dev, int strict)
> >  {
> > --
> > 2.1.0
> >