On 26 April 2016 at 19:44, Jesse Gross <je...@kernel.org> wrote:
> On Thu, Apr 21, 2016 at 2:07 PM, Joe Stringer <j...@ovn.org> wrote:
>> diff --git
>> a/datapath/linux/compat/include/net/netfilter/ipv6/nf_defrag_ipv6.h
>> b/datapath/linux/compat/include/net/netfilter/ipv6/nf_defrag_ipv6.h
>> index fe99ced37227..a3b86dab2c9c 100644
>> --- a/datapath/linux/compat/include/net/netfilter/ipv6/nf_defrag_ipv6.h
>> +++ b/datapath/linux/compat/include/net/netfilter/ipv6/nf_defrag_ipv6.h
>> @@ -16,17 +16,17 @@
>> #define OVS_NF_DEFRAG6_BACKPORT 1
>> struct sk_buff *rpl_nf_ct_frag6_gather(struct net *net, struct sk_buff *skb,
>> u32 user);
>> +#define nf_ct_frag6_gather rpl_nf_ct_frag6_gather
>> +#endif /* HAVE_NF_CT_FRAG6_CONSUME_ORIG */
>> +
>> +#ifdef OVS_NF_DEFRAG6_BACKPORT
>> int __init rpl_nf_ct_frag6_init(void);
>> void rpl_nf_ct_frag6_cleanup(void);
>> -void rpl_nf_ct_frag6_consume_orig(struct sk_buff *skb);
>> -#define nf_ct_frag6_gather rpl_nf_ct_frag6_gather
>> -#else /* HAVE_NF_CT_FRAG6_CONSUME_ORIG */
>> +#else /* !OVS_NF_DEFRAG6_BACKPORT */
>> static inline int __init rpl_nf_ct_frag6_init(void) { return 0; }
>> static inline void rpl_nf_ct_frag6_cleanup(void) { }
>> -static inline void rpl_nf_ct_frag6_consume_orig(struct sk_buff *skb) { }
>> -#endif /* HAVE_NF_CT_FRAG6_CONSUME_ORIG */
>> +#endif /* OVS_NF_DEFRAG6_BACKPORT */
>> #define nf_ct_frag6_init rpl_nf_ct_frag6_init
>> #define nf_ct_frag6_cleanup rpl_nf_ct_frag6_cleanup
>> -#define nf_ct_frag6_consume_orig rpl_nf_ct_frag6_consume_orig
>
> I'm not sure that I totally understand what is going on in this file.
> In particular, although not directly related to this patch, I'm not
> sure why we define rpl_nf_ct_frag6_init()/cleanup() to be no-ops in
> cases where we don't have OVS_NF_DEFRAG6_BACKPORT. On new kernels,
> shouldn't we be using the upstream definitions of these functions? The
> values initialized seem to be used by functions which aren't
> backported.
In upstream, we depend on the exported symbol nf_ct_frag6_gather()
which ensures that nf_defrag_ipv6 module is loaded when loading
openvswitch. During nf_defrag_ipv6 module load, in nf_defrag_init() it
will invoke nf_ct_frag6_init(), initializing the IPv6 fragmentation
handlers and cache.
In out-of-tree, depending on the upstream kernel, we may be able to
rely on the same behaviour from upstream, however if
nf_ct_frag6_gather() is not available then we will backport ipv6
defrag so we need to do this initialization ourselves. In
datapath/compat.h, compat_init() is invoked during openvswitch module
load which invokes nf_ct_frag6_init() to perform this initialization
if necessary.
When depending on a kernel which exports nf_ct_frag6_gather(), we
don't need to do any initialization, so we define this function as a
no-op and rely on the upstream ipv6_defrag.
When nf_ct_frag6_gather() is not exported, we are unable to depend on
the upstream module so we rely on our own backport. In this case, we
provide the implementation of nf_ct_frag6_init().
> More minor but it also seems odd that rpl_nf_ct_frag6_gather() is
> declared in the first #ifdef but then actually defined under
> OVS_NF_DEFRAG6_BACKPORT like all of the other functions. What's the
> reason for separating it out this way?
This patch shifts the #define directly below the declaration.. I think
this patch fixes what you're describing here?
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