[Devel] Re: [patch 1/2][NETNS][RFD] store the network namespace pointer in the dst_entry structure

[Eric W. Biederman]

Daniel Lezcano <dlezcano at fr.ibm.com> writes:

> Store the network namespace pointer in the dst_entry structure when it is
> allocated. 
> The different protocols redefine the route object as a derivate object from
> dst_entry. So using the dst_entry to store the network namespace pointer will
> allow to take into account the ipv4, ipv6, dccp protocols in one shot through
> the different route objects, rtable, rt6_info, ...
>
> ---
>  include/net/dst.h      |    3 ++-
>  net/core/dst.c         |    3 ++-
>  net/decnet/dn_route.c  |    4 ++--
>  net/ipv4/route.c       |   14 +++++++-------
>  net/ipv6/route.c       |   18 ++++++++++--------
>  net/xfrm/xfrm_policy.c |    2 +-
>  6 files changed, 24 insertions(+), 20 deletions(-)
>
> Index: linux-2.6-netns/include/net/dst.h
> ===================================================================
> --- linux-2.6-netns.orig/include/net/dst.h
> +++ linux-2.6-netns/include/net/dst.h
> @@ -81,6 +81,7 @@ struct dst_entry
>  		struct dn_route  *dn_next;
>  	};
>  	char			info[0];
> +	struct net		*net;

Unless I'm missing something you just place that net pointer in
the middle of a variable length array.  Weird I don't see us
using that array.

Could you please place the struct net *net pointer up by the
network device pointer.
>  };

I know we need a net pointer in struct rt_table, because it
is a hash table that we can't dynamically allocate so we need
to place a network namespace pointer as part of the hash key.

For the ipv6 fib tables I don't recall needing a net pointer 
as we didn't have a hash table and could instead have separate
roots for different namespaces.

I find this slightly odd as I didn't wind up needing to add
a struct net pointer in struct dst in my proof of concept tree
and struct dst doesn't have a struct flowi so that would not
have prevented it.

Eric





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