Re: [dpdk-dev] ACL priority field

["Ananyev, Konstantin" <konstantin.ananyev@intel.com>]

Hi,

> 
> Hello,
> 
> Can someone clarify what I am interpreting  as a documentation conflict regarding the "priority" field for rte_table_acl_rule_add_params?
> Below documentation says "highest priority wins", but the header file comment says 0 is highest priority. Based on my testing with
> conflicting entries, I would like ask if we can/should update the documentation/descriptions to state "the lowest non-negative integer
> priority value will be selected". Highest priority implies select X, when X > Y >= 0. However, based on my testing, that is not the case.
> Instead, Y is selected.
> 
> From: https://doc.dpdk.org/guides/prog_guide/packet_classif_access_ctrl.html
> 
> When creating a set of rules, for each rule, additional information must be supplied also:
> *         priority: A weight to measure the priority of the rules (higher is better)... If the input tuple matches more than one rule, then the rule
> with the higher priority is returned. Note that if the input tuple matches more than one rule and these rules have equal priority, it is
> undefined which rule is returned as a match. It is recommended to assign a unique priority for each rule.
> From: http://doc.dpdk.org/api/structrte__table__acl__rule__add__params.html
> 
> int32_t priority
> ACL rule priority, with 0 as the highest priority

I think you are mixing 2 different entities here:
librte_acl and librte_table.
For librte_acl - higher priority wins. 
librte_table_acl.c uses librte_acl inside,
but AFAIK has reverse ordering for priority:
'lesser priority wins'.
Inside it reverts rules priority before adding it
into the ACL lib ctx. 

static int
rte_table_acl_entry_add(
        void *table,
        void *key,
        void *entry,
        int *key_found,
        void **entry_ptr)
{
   ...
  if (rule->priority > RTE_ACL_MAX_PRIORITY) {
                RTE_LOG(ERR, TABLE, "%s: Priority is too high\n", __func__);
                return -EINVAL;
        }

        /* Setup rule data structure */
        memset(&acl_rule, 0, sizeof(acl_rule));
        ...
        acl_rule.data.priority = RTE_ACL_MAX_PRIORITY - rule->priority;