Re: [dpdk-dev] [PATCH v5 2/6] net/mlx5: support basic flow items and actions

[Adrien Mazarguil <adrien.mazarguil@6wind.com>]

Hi Ferruh,

On Wed, Jan 04, 2017 at 05:49:46PM +0000, Ferruh Yigit wrote:
> Hi Nelio,
> 
> A quick question.

I'll reply since it's related to the API.

> On 12/29/2016 3:15 PM, Nelio Laranjeiro wrote:
> > Introduce initial software for rte_flow rules.
> > 
> > VLAN, VXLAN are still not supported.
> > 
> > Signed-off-by: Nelio Laranjeiro <nelio.laranjeiro@6wind.com>
> > Acked-by: Adrien Mazarguil <adrien.mazarguil@6wind.com>
> 
> <...>
> 
> > +static int
> > +priv_flow_validate(struct priv *priv,
> > +		   const struct rte_flow_attr *attr,
> > +		   const struct rte_flow_item items[],
> > +		   const struct rte_flow_action actions[],
> > +		   struct rte_flow_error *error,
> > +		   struct mlx5_flow *flow)
> > +{
> > +	const struct mlx5_flow_items *cur_item = mlx5_flow_items;
> 
> <...>
> 
> > +	for (; items->type != RTE_FLOW_ITEM_TYPE_END; ++items) {
> <...>
> > +	}
> > +	for (; actions->type != RTE_FLOW_ACTION_TYPE_END; ++actions) {
> <...>
> > +	}
> 
> Is it guarantied in somewhere that items or actions terminated with
> TYPE_END?

Yes, since it's now the only way to terminate items/actions lists [1][2].
There used to be a "max" value in the original draft but it seemed redundant
and proved annoying to use, and was therefore dropped.

END items/actions behave like a NUL terminator for C strings. They are
likewise defined with value 0 for convenience.

> And these fields are direct inputs from user.
> Is there a way to verify user provided values are with TYPE_END terminated?

No, applications must check for its presence (they normally add it
themselves) before feeding these lists to PMDs. I think that's safe enough.

Note the testpmd flow command does not allow entering a flow rule without
"end" tokens in both lists, there is no way around this restriction.

[1] http://dpdk.org/doc/guides/prog_guide/rte_flow.html#matching-pattern
[2] http://dpdk.org/doc/guides/prog_guide/rte_flow.html#actions

-- 
Adrien Mazarguil
6WIND