netdev - Re: [PATCH net-next 1/1] net sched actions: Add support for user cookies

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Date:   Sun, 15 Jan 2017 07:59:31 -0500
From:   Jamal Hadi Salim <jhs@...atatu.com>
To:     Jiri Pirko <jiri@...nulli.us>
Cc:     davem@...emloft.net, netdev@...r.kernel.org, jiri@...lanox.com,
        paulb@...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 1/1] net sched actions: Add support for user
 cookies

On 17-01-15 04:11 AM, Jiri Pirko wrote:
> Subject should contain "V2"
>
> Sat, Jan 14, 2017 at 10:52:44PM CET, jhs@...atatu.com 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(using two 64bit values to represent the 128 bits):
>
> Looks like you did not update the description.
>

Yikes. Yes - will send v3.

>>

>> Signed-off-by: Jamal Hadi Salim <jhs@...atatu.com>
>
> V1->V2 changelog would ne nice.
>

Will do.

>
>> ---
>> include/net/act_api.h        |  1 +
>> include/uapi/linux/pkt_cls.h | 11 +++++++++++
>> net/sched/act_api.c          | 28 ++++++++++++++++++++++++++--
>> 3 files changed, 38 insertions(+), 2 deletions(-)
>>
>> 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;
>
> I wonder if we just can't do:
> struct tc_cookie act_ck;
> You would safe kzalloc. I don't have strong opinion though..
>

Lets spare some RAM. I'll keep it the way it is.

>
>> };
>> #define tcf_head	common.tcfa_head
>> #define tcf_index	common.tcfa_index
>> diff --git a/include/uapi/linux/pkt_cls.h b/include/uapi/linux/pkt_cls.h
>> index 1e5e1dd..063bc89 100644
>> --- a/include/uapi/linux/pkt_cls.h
>> +++ b/include/uapi/linux/pkt_cls.h
>> @@ -4,6 +4,16 @@
>> #include <linux/types.h>
>> #include <linux/pkt_sched.h>
>>
>> +#define MAX_TC_COOKIE_SZ 16
>
> I like to have some "namespace" prefix for user api.
> "TC_COOKIE_MAX_SIZE" perhaps?
>

I just cutnpasted from something familiar: MAX_PHYS_ITEM_ID_LEN ;->
Will make the change.

>> +
>> +/* This structure holds cookie structure that is passed from user
>> + * to the kernel for actions and classifiers
>> + */
>> +struct tc_cookie {
>> +	unsigned char ck[MAX_TC_COOKIE_SZ];
>> +	unsigned char ck_len;
>
> This struct should certainly not be in UAPI header.
>

I will move it.

>
>> +};
>> +
>> /* Action attributes */
>> enum {
>> 	TCA_ACT_UNSPEC,
>> @@ -12,6 +22,7 @@ enum {
>> 	TCA_ACT_INDEX,
>> 	TCA_ACT_STATS,
>> 	TCA_ACT_PAD,
>> +	TCA_ACT_COOKIE,
>> 	__TCA_ACT_MAX
>> };


>> +		memcpy((void *)a->act_ck->ck, nla_data(tb[TCA_ACT_COOKIE]),
>
>                        Unneeded (void *) cast.
>

ok. I think gcc whined for some reason.

Will post after some test.

cheers,
jamal