netdev - Re: [ovs-dev] [patch net-next RFC v2 2/6] skbuff: add "missed_flow" flag

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Message-ID: <20140326172501.GI2869@minipsycho.orion>
Date:	Wed, 26 Mar 2014 18:25:01 +0100
From:	Jiri Pirko <jiri@...nulli.us>
To:	Alexei Starovoitov <alexei.starovoitov@...il.com>
Cc:	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	john.r.fastabend@...el.com, Eric Dumazet <edumazet@...gle.com>,
	andy@...yhouse.net, "dev@...nvswitch.org" <dev@...nvswitch.org>,
	f.fainelli@...il.com, jeffrey.t.kirsher@...el.com,
	Or Gerlitz <ogerlitz@...lanox.com>, ben@...adent.org.uk,
	roopa@...ulusnetworks.com, jhs@...atatu.com,
	linville@...driver.com, vyasevic@...hat.com, nhorman@...driver.com,
	sfeldma@...ulusnetworks.com, stephen@...workplumber.org,
	Daniel Borkmann <dborkman@...hat.com>,
	"David S. Miller" <davem@...emloft.net>
Subject: Re: [ovs-dev] [patch net-next RFC v2 2/6] skbuff: add "missed_flow"
 flag

Wed, Mar 26, 2014 at 05:59:12PM CET, alexei.starovoitov@...il.com wrote:
>On Wed, Mar 26, 2014 at 9:31 AM, Jiri Pirko <jiri@...nulli.us> wrote:
>> This flag sets incoming switch device in order to let know that the flow
>> which the skb is part of is missed. Listener may react to it
>> appropriately,
>>
>> Signed-off-by: Jiri Pirko <jiri@...nulli.us>
>> ---
>>  include/linux/filter.h |  1 +
>>  include/linux/skbuff.h | 13 +++++++++++++
>>  net/core/filter.c      |  3 +++
>>  3 files changed, 17 insertions(+)
>>
>> diff --git a/include/linux/filter.h b/include/linux/filter.h
>> index e568c8e..38c7c04 100644
>> --- a/include/linux/filter.h
>> +++ b/include/linux/filter.h
>> @@ -154,6 +154,7 @@ enum {
>>         BPF_S_ANC_VLAN_TAG,
>>         BPF_S_ANC_VLAN_TAG_PRESENT,
>>         BPF_S_ANC_PAY_OFFSET,
>> +       BPF_S_ANC_MISSED_FLOW,
>
>Interesting use case for bpf...
>looks like it's not connected to userspace.
>Are you trying to extend ovs with switchdev api and bpf at once?
>How do you plan to use this bpf extension?

The motive fot this is to provides a user (userspace app) possibility to
get all skbs which were "flow-missed". He can adjust the filter so that
only these can get through.

>
>Thanks
>Alexei
>
>>  };
>>
>>  #endif /* __LINUX_FILTER_H__ */
>> diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
>> index 03db95a..0100c2f 100644
>> --- a/include/linux/skbuff.h
>> +++ b/include/linux/skbuff.h
>> @@ -567,6 +567,7 @@ struct sk_buff {
>>          * headers if needed
>>          */
>>         __u8                    encapsulation:1;
>> +       __u8                    missed_flow:1;
>>         /* 6/8 bit hole (depending on ndisc_nodetype presence) */
>>         kmemcheck_bitfield_end(flags2);
>>
>> @@ -2993,5 +2994,17 @@ static inline unsigned int skb_gso_network_seglen(const struct sk_buff *skb)
>>                                skb_network_header(skb);
>>         return hdr_len + skb_gso_transport_seglen(skb);
>>  }
>> +
>> +/**
>> + * skb_mark_missed_flow - marks skb as a part of missed flow
>> + * @skb: buffer
>> + *
>> + * Marks skb as a part of missed flow.
>> + */
>> +static inline void skb_mark_missed_flow(struct sk_buff *skb)
>> +{
>> +       skb->missed_flow = 1;
>> +}
>> +
>>  #endif /* __KERNEL__ */
>>  #endif /* _LINUX_SKBUFF_H */
>> diff --git a/net/core/filter.c b/net/core/filter.c
>> index ad30d62..048f11a 100644
>> --- a/net/core/filter.c
>> +++ b/net/core/filter.c
>> @@ -350,6 +350,9 @@ load_b:
>>                 case BPF_S_ANC_PAY_OFFSET:
>>                         A = __skb_get_poff(skb);
>>                         continue;
>> +               case BPF_S_ANC_MISSED_FLOW:
>> +                       A = !!skb->missed_flow;
>> +                       continue;
>>                 case BPF_S_ANC_NLATTR: {
>>                         struct nlattr *nla;
>>
>> --
>> 1.8.5.3
>>
>> _______________________________________________
>> dev mailing list
>> dev@...nvswitch.org
>> http://openvswitch.org/mailman/listinfo/dev
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