[ovs-dev] relationship between dpcls_rule and dp_netdev_flow

[Joo Kim]

Hello,

In this OVS (2.6) code below,
It seems that a dp_netdev_flow obj contains a dpcls_rule struct, and given
a dpcls_rule, it gets the corresponding dp_netdev_flow via
dp_netdev_flow_cast().
Does it mean dpcls_rule  and dp_netdev_flow have an 1-1 mapping
relationship?
But, as I understand,  dpcls_rule could have a wildcard which can match
multiple flows. Then, how does dp_netdev_flow_cast() (which seems to assume
1-1 mapping) make sense?


struct dp_netdev_flow {
    const struct flow flow;      /* Unmasked flow that created this entry.
*/
    /* Hash table index by unmasked flow. */
    const struct cmap_node node; /* In owning dp_netdev_pmd_thread's */
                                 /* 'flow_table'. */
…
    /* Packet classification. */
    struct dpcls_rule cr;        /* In owning dp_netdev's 'cls'. */
    /* 'cr' must be the last member. */
};



static struct dp_netdev_flow *
dp_netdev_flow_cast(const struct dpcls_rule *cr)
{
    return cr ? CONTAINER_OF(cr, struct dp_netdev_flow, cr) : NULL;
}


static struct dp_netdev_flow *
dp_netdev_pmd_lookup_flow(struct dp_netdev_pmd_thread *pmd,
                          const struct netdev_flow_key *key,
                          int *lookup_num_p)
{
    struct dpcls *cls;
    struct dpcls_rule *rule;
    odp_port_t in_port = u32_to_odp(MINIFLOW_GET_U32(&key->mf, in_port));
   struct dp_netdev_flow *netdev_flow = NULL;

    cls = dp_netdev_pmd_lookup_dpcls(pmd, in_port);
    if (OVS_LIKELY(cls)) {
        dpcls_lookup(cls, key, &rule, 1, lookup_num_p);
        netdev_flow = dp_netdev_flow_cast(rule);  <<<<<
    }
    return netdev_flow;
}