set_validation_data register weight manually, do not use refund whe…

…n the pre dispatch is zero. (paritytech#7327)

Related paritytech#6772

For an extrinsic, in the post dispatch info, the actual weight is only
used to reclaim unused weight. If the actual weight is more than the pre
dispatch weight, then the extrinsic is using the minimum, e.g., the
weight used registered in pre dispatch.

In parachain-system pallet one call is `set_validation_data`. This call
is returning an actual weight, but the pre-dispatch weight is 0.

This PR fix the disregard of actual weight of `set_validation_data` by
registering it manually.

cumulus/pallets/parachain-system/src/lib.rs

@@ -45,7 +45,7 @@ use cumulus_primitives_core::{
 use cumulus_primitives_parachain_inherent::{MessageQueueChain, ParachainInherentData};
 use frame_support::{
 	defensive,
-	dispatch::{DispatchResult, Pays, PostDispatchInfo},
+	dispatch::DispatchResult,
 	ensure,
 	inherent::{InherentData, InherentIdentifier, ProvideInherent},
 	traits::{Get, HandleMessage},
@@ -567,11 +567,12 @@ pub mod pallet {
 		/// if the appropriate time has come.
 		#[pallet::call_index(0)]
 		#[pallet::weight((0, DispatchClass::Mandatory))]
-		// TODO: This weight should be corrected.
+		// TODO: This weight should be corrected. Currently the weight is registered manually in the
+		// call with `register_extra_weight_unchecked`.
 		pub fn set_validation_data(
 			origin: OriginFor<T>,
 			data: ParachainInherentData,
-		) -> DispatchResultWithPostInfo {
+		) -> DispatchResult {
 			ensure_none(origin)?;
 			assert!(
 				!<ValidationData<T>>::exists(),
@@ -692,7 +693,12 @@ pub mod pallet {
 				vfp.relay_parent_number,
 			));
 
-			Ok(PostDispatchInfo { actual_weight: Some(total_weight), pays_fee: Pays::No })
+			frame_system::Pallet::<T>::register_extra_weight_unchecked(
+				total_weight,
+				DispatchClass::Mandatory,
+			);
+
+			Ok(())
 		}
 
 		#[pallet::call_index(1)]

prdoc/pr_7327.prdoc

@@ -0,0 +1,11 @@
+title: Correctly register the weight n `set_validation_data` in `cumulus-pallet-parachain-system`
+
+doc:
+  - audience: Runtime Dev
+    description: |
+        The actual weight of the call was register as a refund, but the pre-dispatch weight is 0,
+        and we can't refund from 0. Now the actual weight is registered manually instead of ignored.
+
+crates:
+  - name: cumulus-pallet-parachain-system
+    bump: patch