UFT tables should not attempt to delegate eviction score

lib/opte/src/engine/flow_table.rs

@@ -66,6 +66,12 @@ impl Ttl {
     }
 }
 
+/// An eviction policy table which makes TCP flow entries without live flowstate
+/// parents trivially evictable. When present, the TCP flow state will signal
+/// a value to be used in its place.
+#[derive(Clone, Copy, Debug)]
+pub struct TtlDelegateTcp(pub Ttl);
+
 /// A metric of how stale a flow entry is, used to determine whether
 /// any existing entry can be evicted to make room for a new one.
 #[derive(Copy, Clone, Debug, Eq, Ord, PartialEq, PartialOrd, Default)]
@@ -102,6 +108,20 @@ impl<S: FlowState> ExpiryPolicy<S> for Ttl {
         self.is_expired(entry.last_hit(), now)
     }
 
+    fn eviction_priority(
+        &self,
+        _entry: &FlowEntry<S>,
+        _now: Moment,
+    ) -> Option<EvictionPriority> {
+        None
+    }
+}
+
+impl<S: FlowState> ExpiryPolicy<S> for TtlDelegateTcp {
+    fn is_expired(&self, entry: &FlowEntry<S>, now: Moment) -> bool {
+        self.0.is_expired(entry.last_hit(), now)
+    }
+
     fn eviction_priority(
         &self,
         entry: &FlowEntry<S>,

lib/opte/src/engine/layer.rs

@@ -40,7 +40,9 @@ use crate::ddi::kstat::KStatProvider;
 use crate::ddi::kstat::KStatU64;
 use crate::ddi::mblk::MsgBlk;
 use crate::ddi::time::Moment;
+use crate::engine::flow_table::FLOW_DEF_TTL;
 use crate::engine::flow_table::FlowState;
+use crate::engine::flow_table::TtlDelegateTcp;
 use alloc::ffi::CString;
 use alloc::string::String;
 use alloc::string::ToString;
@@ -326,8 +328,18 @@ impl LayerFlowTable {
         Self {
             count: 0,
             limit,
-            ft_in: FlowTable::new(port, &format!("{layer}_in"), limit, None),
-            ft_out: FlowTable::new(port, &format!("{layer}_out"), limit, None),
+            ft_in: FlowTable::new(
+                port,
+                &format!("{layer}_in"),
+                limit,
+                Some(Arc::new(TtlDelegateTcp(FLOW_DEF_TTL))),
+            ),
+            ft_out: FlowTable::new(
+                port,
+                &format!("{layer}_out"),
+                limit,
+                Some(Arc::new(TtlDelegateTcp(FLOW_DEF_TTL))),
+            ),
         }
     }