Subject: Re: [RFC bpf-next 2/7] net: introduce skb_net helper

From: Stanislav Fomichev <[email-masked]>
Date: Tue, 5 Feb 2019 12:42:01 -0800

On 02/05, Willem de Bruijn wrote:
> On Tue, Feb 5, 2019 at 12:57 PM Stanislav Fomichev <[email-masked]> wrote:
> >
> > skb_net returns network namespace from the associated device or socket.
> >
> > This will be used in the next commit.
> >
> > Signed-off-by: Stanislav Fomichev <[email-masked]>
> > ---
> >  include/linux/skbuff.h |  2 ++
> >  net/core/skbuff.c      | 10 ++++++++++
> >  2 files changed, 12 insertions(+)
> >
> > diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
> > index ad883ab2762c..28723a86efdf 100644
> > --- a/include/linux/skbuff.h
> > +++ b/include/linux/skbuff.h
> > @@ -4343,5 +4343,7 @@ static inline __wsum lco_csum(struct sk_buff *skb)
> >         return csum_partial(l4_hdr, csum_start - l4_hdr, partial);
> >  }
> >
> > +struct net *skb_net(const struct sk_buff *skb);
> > +
> >  #endif /* __KERNEL__ */
> >  #endif /* _LINUX_SKBUFF_H */
> > diff --git a/net/core/skbuff.c b/net/core/skbuff.c
> > index 23c9cf100bd4..016db13fa2b6 100644
> > --- a/net/core/skbuff.c
> > +++ b/net/core/skbuff.c
> > @@ -5585,6 +5585,16 @@ void skb_condense(struct sk_buff *skb)
> >         skb->truesize = SKB_TRUESIZE(skb_end_offset(skb));
> >  }
> >
> > +struct net *skb_net(const struct sk_buff *skb)
> > +{
> > +       if (skb->dev)
> > +               return dev_net(skb->dev);
> > +       else if (skb->sk)
> > +               return sock_net(skb->sk);
> > +       return NULL;
> > +}
> > +EXPORT_SYMBOL(skb_net);
> 
> If this needs a helper it is probably better static inline in the header.
I did that initially in skbuff.h as inline, but it is missing some
struct definitions, decided to go with this for RFC. Will look into
inlining.