netdev - Re: [patch net-next] net: sched: add helpers to handle extended actions

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Message-ID: <6450af04-a6d4-866e-82ee-424ff54b2ef3@mojatatu.com>
Date:   Sun, 30 Apr 2017 10:08:15 -0400
From:   Jamal Hadi Salim <jhs@...atatu.com>
To:     Jiri Pirko <jiri@...nulli.us>, netdev@...r.kernel.org
Cc:     davem@...emloft.net, xiyou.wangcong@...il.com, mlxsw@...lanox.com
Subject: Re: [patch net-next] net: sched: add helpers to handle extended
 actions

Jiri,

With "goto chain X" this will have to be more generalized. Maybe
we have 0xAXXXXXXX Where "A" recognizes the extension with
current values ACT_JUMP(0x1) and GOTO_CHAIN(maybe 0x2)
and the rest "XXXXXXX" is a free floating parameter values
which carry the goto count for ACT_JUMP and GOTO_CHAIN chain-id.

cheers,
jamal

On 17-04-28 12:13 PM, Jiri Pirko wrote:
> From: Jiri Pirko <jiri@...lanox.com>
>
> Jump is now the only one using value action opcode. This is going to
> change soon. So introduce helpers to work with this. Convert TC_ACT_JUMP.
>
> Signed-off-by: Jiri Pirko <jiri@...lanox.com>
> ---
>  include/uapi/linux/pkt_cls.h | 15 ++++++++++++++-
>  net/sched/act_api.c          |  2 +-
>  2 files changed, 15 insertions(+), 2 deletions(-)
>
> diff --git a/include/uapi/linux/pkt_cls.h b/include/uapi/linux/pkt_cls.h
> index f1129e3..d613be3 100644
> --- a/include/uapi/linux/pkt_cls.h
> +++ b/include/uapi/linux/pkt_cls.h
> @@ -37,7 +37,20 @@ enum {
>  #define TC_ACT_QUEUED		5
>  #define TC_ACT_REPEAT		6
>  #define TC_ACT_REDIRECT		7
> -#define TC_ACT_JUMP		0x10000000
> +
> +/* There is a special kind of actions called "extended actions",
> + * which need a value parameter. These have a local opcode located in
> + * the highest nibble, starting from 1. The rest of the bits
> + * are used to carry the value. These two parts together make
> + * a combined opcode.
> + */
> +#define __TC_ACT_EXT_SHIFT 28
> +#define __TC_ACT_EXT(local) ((local) << __TC_ACT_EXT_SHIFT)
> +#define TC_ACT_EXT_VAL_MASK ((1 << __TC_ACT_EXT_SHIFT) - 1)
> +#define TC_ACT_EXT_CMP(combined, opcode) \
> +	(((combined) & (~TC_ACT_EXT_VAL_MASK)) == opcode)
> +
> +#define TC_ACT_JUMP __TC_ACT_EXT(1)
>
>  /* Action type identifiers*/
>  enum {
> diff --git a/net/sched/act_api.c b/net/sched/act_api.c
> index 7f2cd70..a90e8f3 100644
> --- a/net/sched/act_api.c
> +++ b/net/sched/act_api.c
> @@ -453,7 +453,7 @@ int tcf_action_exec(struct sk_buff *skb, struct tc_action **actions,
>  		if (ret == TC_ACT_REPEAT)
>  			goto repeat;	/* we need a ttl - JHS */
>
> -		if (ret & TC_ACT_JUMP) {
> +		if (TC_ACT_EXT_CMP(ret, TC_ACT_JUMP)) {
>  			jmp_prgcnt = ret & TCA_ACT_MAX_PRIO_MASK;
>  			if (!jmp_prgcnt || (jmp_prgcnt > nr_actions)) {
>  				/* faulty opcode, stop pipeline */
>