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Date: Wed, 18 Jan 2017 07:13:22 -0500
From: Jamal Hadi Salim <jhs@...atatu.com>
To: Paul Blakey <paulb@...lanox.com>, davem@...emloft.net
Cc: netdev@...r.kernel.org, jiri@...lanox.com,
john.fastabend@...il.com, simon.horman@...ronome.com,
mrv@...atatu.com, hadarh@...lanox.com, ogerlitz@...lanox.com,
roid@...lanox.com, xiyou.wangcong@...il.com, daniel@...earbox.net
Subject: Re: [PATCH net-next v4 1/2] net sched actions: Add support for user
cookies
On 17-01-18 06:47 AM, Paul Blakey wrote:
>
>
> On 17/01/2017 13:11, Jamal Hadi Salim wrote:
>> From: Jamal Hadi Salim <jhs@...atatu.com>
>>
>> Introduce optional 128-bit action cookie.
>> Like all other cookie schemes in the networking world (eg in protocols
>> like http or existing kernel fib protocol field, etc) the idea is to save
>> user state that when retrieved serves as a correlator. The kernel
>> _should not_ intepret it. The user can store whatever they wish in the
>> 128 bits.
>>
>> Sample exercise(showing variable length use of cookie)
>>
>> .. create an accept action with cookie a1b2c3d4
>> sudo $TC actions add action ok index 1 cookie a1b2c3d4
>>
>> .. dump all gact actions..
>> sudo $TC -s actions ls action gact
>>
>> action order 0: gact action pass
>> random type none pass val 0
>> index 1 ref 1 bind 0 installed 5 sec used 5 sec
>> Action statistics:
>> Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0)
>> backlog 0b 0p requeues 0
>> cookie a1b2c3d4
>>
>> .. bind the accept action to a filter..
>> sudo $TC filter add dev lo parent ffff: protocol ip prio 1 \
>> u32 match ip dst 127.0.0.1/32 flowid 1:1 action gact index 1
>>
>> ... send some traffic..
>> $ ping 127.0.0.1 -c 3
>> PING 127.0.0.1 (127.0.0.1) 56(84) bytes of data.
>> 64 bytes from 127.0.0.1: icmp_seq=1 ttl=64 time=0.020 ms
>> 64 bytes from 127.0.0.1: icmp_seq=2 ttl=64 time=0.027 ms
>> 64 bytes from 127.0.0.1: icmp_seq=3 ttl=64 time=0.038 ms
>>
>> --- 127.0.0.1 ping statistics ---
>> 3 packets transmitted, 3 received, 0% packet loss, time 2109ms
>> rtt min/avg/max/mdev = 0.020/0.028/0.038/0.008 ms 1
>>
>> ... show some stats
>> $ sudo $TC -s actions get action gact index 1
>>
>> action order 1: gact action pass
>> random type none pass val 0
>> index 1 ref 2 bind 1 installed 204 sec used 5 sec
>> Action statistics:
>> Sent 12168 bytes 164 pkt (dropped 0, overlimits 0 requeues 0)
>> backlog 0b 0p requeues 0
>> cookie a1b2c3d4
>>
>> .. try longer cookie...
>> $ sudo $TC actions replace action ok index 1 cookie 1234567890abcdef
>> .. dump..
>> $ sudo $TC -s actions ls action gact
>>
>> action order 1: gact action pass
>> random type none pass val 0
>> index 1 ref 2 bind 1 installed 204 sec used 5 sec
>> Action statistics:
>> Sent 12168 bytes 164 pkt (dropped 0, overlimits 0 requeues 0)
>> backlog 0b 0p requeues 0
>> cookie 1234567890abcdef
>>
>> Signed-off-by: Jamal Hadi Salim <jhs@...atatu.com>
>> ---
>> include/net/act_api.h | 1 +
>> include/net/pkt_cls.h | 8 ++++++++
>> include/uapi/linux/pkt_cls.h | 3 +++
>> net/sched/act_api.c | 25 +++++++++++++++++++++++++
>> 4 files changed, 37 insertions(+)
>>
>> diff --git a/include/net/act_api.h b/include/net/act_api.h
>> index 1d71644..0692458 100644
>> --- a/include/net/act_api.h
>> +++ b/include/net/act_api.h
>> @@ -41,6 +41,7 @@ struct tc_action {
>> struct rcu_head tcfa_rcu;
>> struct gnet_stats_basic_cpu __percpu *cpu_bstats;
>> struct gnet_stats_queue __percpu *cpu_qstats;
>> + struct tc_cookie *act_ck;
>> };
>> #define tcf_head common.tcfa_head
>> #define tcf_index common.tcfa_index
>> diff --git a/include/net/pkt_cls.h b/include/net/pkt_cls.h
>> index f0a0514..e0bc7e8 100644
>> --- a/include/net/pkt_cls.h
>> +++ b/include/net/pkt_cls.h
>> @@ -515,4 +515,12 @@ struct tc_cls_bpf_offload {
>> u32 gen_flags;
>> };
>>
>> +
>> +/* This structure holds cookie structure that is passed from user
>> + * to the kernel for actions and classifiers
>> + */
>> +struct tc_cookie {
>> + unsigned char ck[TC_COOKIE_MAX_SIZE];
>> + unsigned char ck_len;
>> +};
>> #endif
>> diff --git a/include/uapi/linux/pkt_cls.h b/include/uapi/linux/pkt_cls.h
>> index 1e5e1dd..2d2414e 100644
>> --- a/include/uapi/linux/pkt_cls.h
>> +++ b/include/uapi/linux/pkt_cls.h
>> @@ -4,6 +4,8 @@
>> #include <linux/types.h>
>> #include <linux/pkt_sched.h>
>>
>> +#define TC_COOKIE_MAX_SIZE 16
>> +
>> /* Action attributes */
>> enum {
>> TCA_ACT_UNSPEC,
>> @@ -12,6 +14,7 @@ enum {
>> TCA_ACT_INDEX,
>> TCA_ACT_STATS,
>> TCA_ACT_PAD,
>> + TCA_ACT_COOKIE,
>> __TCA_ACT_MAX
>> };
>>
>> diff --git a/net/sched/act_api.c b/net/sched/act_api.c
>> index f04715a..43f1f42 100644
>> --- a/net/sched/act_api.c
>> +++ b/net/sched/act_api.c
>> @@ -24,6 +24,7 @@
>> #include <net/net_namespace.h>
>> #include <net/sock.h>
>> #include <net/sch_generic.h>
>> +#include <net/pkt_cls.h>
>> #include <net/act_api.h>
>> #include <net/netlink.h>
>>
>> @@ -33,6 +34,7 @@ static void free_tcf(struct rcu_head *head)
>>
>> free_percpu(p->cpu_bstats);
>> free_percpu(p->cpu_qstats);
>> + kfree(p->act_ck);
>> kfree(p);
>> }
>>
>> @@ -475,6 +477,12 @@ int tcf_action_destroy(struct list_head *actions,
>> int bind)
>> goto nla_put_failure;
>> if (tcf_action_copy_stats(skb, a, 0))
>> goto nla_put_failure;
>> + if (a->act_ck) {
>> + if (nla_put(skb, TCA_ACT_COOKIE, a->act_ck->ck_len,
>> + a->act_ck))
>> + goto nla_put_failure;
>> + }
>> +
>> nest = nla_nest_start(skb, TCA_OPTIONS);
>> if (nest == NULL)
>> goto nla_put_failure;
>> @@ -575,6 +583,23 @@ struct tc_action *tcf_action_init_1(struct net
>> *net, struct nlattr *nla,
>> if (err < 0)
>> goto err_mod;
>>
>> + if (tb[TCA_ACT_COOKIE]) {
>> + if (nla_len(tb[TCA_ACT_COOKIE]) > TC_COOKIE_MAX_SIZE) {
>> + err = -EINVAL;
>> + goto err_mod;
>> + }
>> +
>> + a->act_ck = kzalloc(sizeof(*a->act_ck), GFP_KERNEL);
>
> Hi Jamal, How about
> struct tc_cookie {
> unsigned int len;
> unsigned long ck[0];
> };
>
> and then:
>
> a->act_ck = kzalloc(sizeof(*a->act_ck) + nla_len(tb[TCA_ACT_COOKIE]),
> GFP_KERNEL);
>
> to save some space?
>
Doesnt make much of a difference in the larger scope. Look at Daniel's
email;
I started incorporating his change...
(Unfortunately my time has run out so i will post the patch later or
tommorow).
>
>
>> + if (unlikely(!a->act_ck)) {
>> + err = -ENOMEM;
>> + goto err_mod;
>> + }
>> +
>> + memcpy(a->act_ck->ck, nla_data(tb[TCA_ACT_COOKIE]),
>> + nla_len(tb[TCA_ACT_COOKIE]));
>> + a->act_ck->ck_len = nla_len(tb[TCA_ACT_COOKIE]);
>> + }
>> +
>> /* module count goes up only when brand new policy is created
>> * if it exists and is only bound to in a_o->init() then
>> * ACT_P_CREATED is not returned (a zero is).
>>
>
>
> Besides if I'll reuse tc_cookie for classifiers, I'll need 20 bytes :)
>
You should be able to change the define when you submit your patch.
cheers,
jamal
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