[ovs-dev] [PATCH V2 02/11] compat: Fix up changes to inet frags in 5.1+

[Gregory Rose]

On 2/28/2020 9:02 AM, Gregory Rose wrote:
> On 2/27/2020 3:54 PM, Yi-Hung Wei wrote:
>> On Wed, Feb 26, 2020 at 9:41 AM Greg Rose <gvrose8192 at gmail.com> wrote:
>>> Since Linux kernel release 5.1 the fragments field of the 
>>> inet_frag_queue
>>> structure is removed and now only the rb_fragments structure with an
>>> rb_node pointer is used for both ipv4 and ipv6.  In addition, the
>>> atomic_sub and atomic_add functions are replaced with their
>>> equivalent long counterparts.
>>>
>>> Signed-off-by: Greg Rose <gvrose8192 at gmail.com>
>>> ---
>>>   acinclude.m4                                  |  2 ++
>>>   datapath/linux/compat/include/net/inet_frag.h | 21 
>>> +++++++++++++++++++++
>>>   2 files changed, 23 insertions(+)
>>>
>>> diff --git a/acinclude.m4 b/acinclude.m4
>>> index db64267..cad76c7 100644
>>> --- a/acinclude.m4
>>> +++ b/acinclude.m4
>>> @@ -1067,6 +1067,8 @@ AC_DEFUN([OVS_CHECK_LINUX_COMPAT], [
>>> [OVS_DEFINE([HAVE_RBTREE_RB_LINK_NODE_RCU])])
>>>     OVS_GREP_IFELSE([$KSRC/include/net/dst_ops.h], [bool 
>>> confirm_neigh],
>>> [OVS_DEFINE([HAVE_DST_OPS_CONFIRM_NEIGH])])
>>> +  OVS_GREP_IFELSE([$KSRC/include/net/inet_frag.h], [fqdir],
>>> +                  [OVS_DEFINE([HAVE_INET_FRAG_FQDIR])])
>>>
>>>     if cmp -s datapath/linux/kcompat.h.new \
>>>               datapath/linux/kcompat.h >/dev/null 2>&1; then
>>> diff --git a/datapath/linux/compat/include/net/inet_frag.h 
>>> b/datapath/linux/compat/include/net/inet_frag.h
>>> index 124c8be..e3c6df3 100644
>>> --- a/datapath/linux/compat/include/net/inet_frag.h
>>> +++ b/datapath/linux/compat/include/net/inet_frag.h
>>> @@ -18,7 +18,16 @@ static inline bool inet_frag_evicting(struct 
>>> inet_frag_queue *q)
>>>   #ifdef HAVE_INET_FRAG_QUEUE_WITH_LIST_EVICTOR
>>>          return !hlist_unhashed(&q->list_evictor);
>>>   #else
>>> +/*
>>> + * We can't use acinclude.m4 to check this as the field 'fragments'
>>> + * also matches 'rb_fragments'.
>>> + */
>>> +#if LINUX_VERSION_CODE < KERNEL_VERSION(5,1,0)
>>>          return (q_flags(q) & INET_FRAG_FIRST_IN) && q->fragments != 
>>> NULL;
>>> +#else
>>> +       return (q_flags(q) & INET_FRAG_FIRST_IN) &&
>>> +                       q->rb_fragments.rb_node != NULL;
>>> +#endif
>>>   #endif /* HAVE_INET_FRAG_QUEUE_WITH_LIST_EVICTOR */
>>>   }
>>>   #endif /* HAVE_INET_FRAG_EVICTING */
>> Yes, it's a bummer if we can not check some fields in the acinclude.m4.
>>
>> It looks like inet_frag_evicting() has been removed by upstream commit
>> 399d1404be66 ("inet: frags: get rif of inet_frag_evicting()") since
>> kernel 4.17, and the only place that we use is in rpl_ipfrag_init() ->
>> ip_expire() when HAVE_CORRECT_MRU_HANDLING is not available.
>> Therefore, how about the following approach that avoids the less
>> reliable kernel version check.
>>
>> --- a/datapath/linux/compat/include/net/inet_frag.h
>> +++ b/datapath/linux/compat/include/net/inet_frag.h
>> @@ -12,6 +12,7 @@
>>   #define qp_flags(qp) (qp->q.flags)
>>   #endif
>>
>> +#ifndef HAVE_CORRECT_MRU_HANDLING
>>   #ifndef HAVE_INET_FRAG_EVICTING
>>   static inline bool inet_frag_evicting(struct inet_frag_queue *q)
>>   {
>> @@ -22,6 +23,7 @@ static inline bool inet_frag_evicting(struct
>> inet_frag_queue *q)
>>   #endif /* HAVE_INET_FRAG_QUEUE_WITH_LIST_EVICTOR */
>>   }
>>   #endif /* HAVE_INET_FRAG_EVICTING */
>> +#endif /* HAVE_CORRECT_MRU_HANDLING */
>>
>>
>> I am good with the rest of the backports in this patch.

Hi Yi-Hung,

I have a V3 set of patches for this series but I found that the 
inet_frags changes in
this patch (with or without your suggested change) are failing tests 59 
and 60 in
check-kmod on a Ubuntu 18.04 system with the 4.15.0-88-generic kernel.  I'm
investigating that issue and should have the updated V3 patches ready as 
soon
as I sort this out.

Thanks,

- Greg