Fix per-ancestor core assignment and add regression test

polkadot/node/network/collator-protocol/src/validator_side_experimental/collation_manager/mod.rs

@@ -246,26 +246,25 @@ impl CollationManager {
 			else {
 				continue;
 			};
+			let session_index =
+				match recv_runtime(request_session_index_for_child(*leaf, sender).await)
+					.await
+					.map_err(Error::Runtime)
+				{
+					Ok(session_index) => session_index,
+					Err(err) => {
+						err.split()?.log();
+						continue;
+					},
+				};
 
 			// Includes the leaf
 			for (idx, ancestor) in allowed_ancestry.iter().enumerate() {
 				if self.per_scheduling_parent.contains_key(&ancestor) {
 					continue;
 				}
 
-				let session_index =
-					match recv_runtime(request_session_index_for_child(*ancestor, sender).await)
-						.await
-						.map_err(Error::Runtime)
-					{
-						Ok(session_index) => session_index,
-						Err(err) => {
-							err.split()?.log();
-							continue;
-						},
-					};
-
-				let core = match self.get_our_core(sender, leaf, session_index).await {
+				let core = match self.get_our_core(sender, ancestor, session_index).await {
 					Ok(assignments) => assignments,
 					Err(err) => {
 						err.split()?.log();

polkadot/node/network/collator-protocol/src/validator_side_experimental/tests.rs

@@ -3732,6 +3732,47 @@ async fn v3_descriptor_unknown_rejected_when_v3_disabled() {
 	test_state.assert_no_messages().await;
 }
 
+#[tokio::test]
+// Check that the core is computed correctly for ancestors.
+async fn core_assignment_uses_ancestor_not_leaf() {
+	let mut test_state = TestState::default();
+	test_state
+		.session_info
+		.get_mut(&1)
+		.unwrap()
+		.group_rotation_info
+		.group_rotation_frequency = 1;
+	test_state
+		.node_features
+		.resize(node_features::FeatureIndex::CandidateReceiptV3 as usize + 1, false);
+	test_state
+		.node_features
+		.set(node_features::FeatureIndex::CandidateReceiptV3 as u8 as usize, true);
+
+	let db = MockDb::default();
+	let mut state = make_state(db.clone(), &mut test_state, get_hash(10)).await;
+	let mut sender = test_state.sender.clone();
+
+	let peer_id = PeerId::random();
+	let (ccr, adv) = dummy_candidate_v3(
+		get_hash(8),
+		get_hash(9),
+		600.into(),
+		peer_id,
+		CoreIndex(2),
+		1,
+		dummy_pvd().hash(),
+	);
+
+	state.handle_peer_connected(&mut sender, peer_id, CollationVersion::V3).await;
+	state.handle_declare(&mut sender, peer_id, 600.into()).await;
+
+	test_state
+		.handle_fetched_collation(&mut state, adv, ccr.to_plain(), None, get_hash(8))
+		.await;
+	assert!(db.witnessed_slash().is_none());
+}
+
 // Launching new collations:
 // - multiple candidates per relay parent (including from implicit view and which occupy future
 //   claims, including which will make claims across different leaves)

prdoc/pr_11485.prdoc

@@ -0,0 +1,9 @@
+title: Fix per-ancestor core assignment and add regression test
+doc:
+- audience: Node Dev
+  description: '`get_our_core` was called with the leaf hash instead of the ancestor
+    hash when computing core assignments in update_view. This caused all scheduling
+    parent to get leaf''s core.'
+crates:
+- name: polkadot-collator-protocol
+  bump: minor