Pvf refactor execute worker errors follow up (#4071)

follow up of https://github.com/paritytech/polkadot-sdk/pull/2604
closes https://github.com/paritytech/polkadot-sdk/pull/2604

- [x] take relevant changes from Marcin's PR 
- [x] extract common duplicate code for workers (low-hanging fruits)

~Some unpassed ci problems are more general and should be fixed in
master (see https://github.com/paritytech/polkadot-sdk/pull/4074)~

Proposed labels: **T0-node**, **R0-silent**, **I4-refactor**

-----

kusama address: FZXVQLqLbFV2otNXs6BMnNch54CFJ1idpWwjMb3Z8fTLQC6

---------

Co-authored-by: s0me0ne-unkn0wn <48632512+s0me0ne-unkn0wn@users.noreply.github.com>

Cargo.lock

@@ -7575,9 +7575,9 @@ checksum = "884e2677b40cc8c339eaefcb701c32ef1fd2493d71118dc0ca4b6a736c93bd67"
 
 [[package]]
 name = "libc"
-version = "0.2.152"
+version = "0.2.153"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "13e3bf6590cbc649f4d1a3eefc9d5d6eb746f5200ffb04e5e142700b8faa56e7"
+checksum = "9c198f91728a82281a64e1f4f9eeb25d82cb32a5de251c6bd1b5154d63a8e7bd"
 
 [[package]]
 name = "libflate"
@@ -13303,7 +13303,6 @@ dependencies = [
  "slotmap",
  "sp-core",
  "sp-maybe-compressed-blob",
- "sp-wasm-interface 20.0.0",
  "tempfile",
  "test-parachain-adder",
  "test-parachain-halt",
@@ -13340,7 +13339,6 @@ name = "polkadot-node-core-pvf-common"
 version = "7.0.0"
 dependencies = [
  "assert_matches",
- "cfg-if",
  "cpu-time",
  "futures",
  "landlock",

polkadot/node/core/pvf/Cargo.toml

@@ -17,8 +17,7 @@ cfg-if = "1.0"
 futures = "0.3.30"
 futures-timer = "3.0.2"
 gum = { package = "tracing-gum", path = "../../gum" }
-is_executable = "1.0.1"
-libc = "0.2.152"
+is_executable = { version = "1.0.1", optional = true }
 pin-project = "1.0.9"
 rand = "0.8.5"
 slotmap = "1.0"
@@ -26,7 +25,9 @@ tempfile = "3.3.0"
 thiserror = { workspace = true }
 tokio = { version = "1.24.2", features = ["fs", "process"] }
 
-parity-scale-codec = { version = "3.6.1", default-features = false, features = ["derive"] }
+parity-scale-codec = { version = "3.6.1", default-features = false, features = [
+	"derive",
+] }
 
 polkadot-parachain-primitives = { path = "../../../parachain" }
 polkadot-core-primitives = { path = "../../../core-primitives" }
@@ -37,14 +38,16 @@ polkadot-node-subsystem = { path = "../../subsystem" }
 polkadot-primitives = { path = "../../../primitives" }
 
 sp-core = { path = "../../../../substrate/primitives/core" }
-sp-wasm-interface = { path = "../../../../substrate/primitives/wasm-interface" }
-sp-maybe-compressed-blob = { path = "../../../../substrate/primitives/maybe-compressed-blob" }
+sp-maybe-compressed-blob = { path = "../../../../substrate/primitives/maybe-compressed-blob", optional = true }
 polkadot-node-core-pvf-prepare-worker = { path = "prepare-worker", optional = true }
 polkadot-node-core-pvf-execute-worker = { path = "execute-worker", optional = true }
 
 [dev-dependencies]
 assert_matches = "1.4.0"
-criterion = { version = "0.4.0", default-features = false, features = ["async_tokio", "cargo_bench_support"] }
+criterion = { version = "0.4.0", default-features = false, features = [
+	"async_tokio",
+	"cargo_bench_support",
+] }
 hex-literal = "0.4.1"
 
 polkadot-node-core-pvf-common = { path = "common", features = ["test-utils"] }
@@ -57,6 +60,7 @@ adder = { package = "test-parachain-adder", path = "../../../parachain/test-para
 halt = { package = "test-parachain-halt", path = "../../../parachain/test-parachains/halt" }
 
 [target.'cfg(target_os = "linux")'.dev-dependencies]
+libc = "0.2.153"
 procfs = "0.16.0"
 rusty-fork = "0.3.0"
 sc-sysinfo = { path = "../../../../substrate/client/sysinfo" }
@@ -70,6 +74,8 @@ ci-only-tests = []
 jemalloc-allocator = ["polkadot-node-core-pvf-common/jemalloc-allocator"]
 # This feature is used to export test code to other crates without putting it in the production build.
 test-utils = [
-	"polkadot-node-core-pvf-execute-worker",
-	"polkadot-node-core-pvf-prepare-worker",
+	"dep:is_executable",
+	"dep:polkadot-node-core-pvf-execute-worker",
+	"dep:polkadot-node-core-pvf-prepare-worker",
+	"dep:sp-maybe-compressed-blob",
 ]

polkadot/node/core/pvf/common/Cargo.toml

@@ -10,14 +10,16 @@ license.workspace = true
 workspace = true
 
 [dependencies]
-cfg-if = "1.0"
 cpu-time = "1.0.0"
 futures = "0.3.30"
 gum = { package = "tracing-gum", path = "../../../gum" }
 libc = "0.2.152"
+nix = { version = "0.27.1", features = ["resource", "sched"] }
 thiserror = { workspace = true }
 
-parity-scale-codec = { version = "3.6.1", default-features = false, features = ["derive"] }
+parity-scale-codec = { version = "3.6.1", default-features = false, features = [
+	"derive",
+] }
 
 polkadot-parachain-primitives = { path = "../../../../parachain" }
 polkadot-primitives = { path = "../../../../primitives" }
@@ -34,7 +36,6 @@ sp-tracing = { path = "../../../../../substrate/primitives/tracing" }
 
 [target.'cfg(target_os = "linux")'.dependencies]
 landlock = "0.3.0"
-nix = { version = "0.27.1", features = ["sched"] }
 
 [target.'cfg(all(target_os = "linux", target_arch = "x86_64"))'.dependencies]
 seccompiler = "0.4.0"

polkadot/node/core/pvf/common/src/error.rs

@@ -136,6 +136,9 @@ pub enum InternalValidationError {
 	/// Could not find or open compiled artifact file.
 	#[error("validation: could not find or open compiled artifact file: {0}")]
 	CouldNotOpenFile(String),
+	/// Could not create a pipe between the worker and a child process.
+	#[error("validation: could not create pipe: {0}")]
+	CouldNotCreatePipe(String),
 	/// Host could not clear the worker cache after a job.
 	#[error("validation: host could not clear the worker cache ({path:?}) after a job: {err}")]
 	CouldNotClearWorkerDir {

polkadot/node/core/pvf/common/src/execute.rs

@@ -30,35 +30,36 @@ pub struct Handshake {
 
 /// The response from the execution worker.
 #[derive(Debug, Encode, Decode)]
-pub enum WorkerResponse {
-	/// The job completed successfully.
-	Ok {
-		/// The result of parachain validation.
-		result_descriptor: ValidationResult,
-		/// The amount of CPU time taken by the job.
-		duration: Duration,
-	},
-	/// The candidate is invalid.
-	InvalidCandidate(String),
-	/// Instantiation of the WASM module instance failed during an execution.
-	/// Possibly related to local issues or dirty node update. May be retried with re-preparation.
-	RuntimeConstruction(String),
+pub struct WorkerResponse {
+	/// The response from the execute job process.
+	pub job_response: JobResponse,
+	/// The amount of CPU time taken by the job.
+	pub duration: Duration,
+}
+
+/// An error occurred in the worker process.
+#[derive(thiserror::Error, Debug, Clone, Encode, Decode)]
+pub enum WorkerError {
 	/// The job timed out.
+	#[error("The job timed out")]
 	JobTimedOut,
 	/// The job process has died. We must kill the worker just in case.
 	///
 	/// We cannot treat this as an internal error because malicious code may have killed the job.
 	/// We still retry it, because in the non-malicious case it is likely spurious.
+	#[error("The job process (pid {job_pid}) has died: {err}")]
 	JobDied { err: String, job_pid: i32 },
 	/// An unexpected error occurred in the job process, e.g. failing to spawn a thread, panic,
 	/// etc.
 	///
 	/// Because malicious code can cause a job error, we must not treat it as an internal error. We
 	/// still retry it, because in the non-malicious case it is likely spurious.
-	JobError(String),
+	#[error("An unexpected error occurred in the job process: {0}")]
+	JobError(#[from] JobError),
 
 	/// Some internal error occurred.
-	InternalError(InternalValidationError),
+	#[error("An internal error occurred: {0}")]
+	InternalError(#[from] InternalValidationError),
 }
 
 /// The result of a job on the execution worker.
@@ -101,7 +102,7 @@ impl JobResponse {
 /// An unexpected error occurred in the execution job process. Because this comes from the job,
 /// which executes untrusted code, this error must likewise be treated as untrusted. That is, we
 /// cannot raise an internal error based on this.
-#[derive(thiserror::Error, Debug, Encode, Decode)]
+#[derive(thiserror::Error, Clone, Debug, Encode, Decode)]
 pub enum JobError {
 	#[error("The job timed out")]
 	TimedOut,
@@ -114,4 +115,7 @@ pub enum JobError {
 	CouldNotSpawnThread(String),
 	#[error("An error occurred in the CPU time monitor thread: {0}")]
 	CpuTimeMonitorThread(String),
+	/// Since the job can return any exit status it wants, we have to treat this as untrusted.
+	#[error("Unexpected exit status: {0}")]
+	UnexpectedExitStatus(i32),
 }

polkadot/node/core/pvf/common/src/lib.rs

@@ -15,6 +15,7 @@
 // along with Polkadot.  If not, see <http://www.gnu.org/licenses/>.
 
 //! Contains functionality related to PVFs that is shared by the PVF host and the PVF workers.
+#![deny(unused_crate_dependencies)]
 
 pub mod error;
 pub mod execute;

polkadot/node/core/pvf/common/src/pvf.rs

@@ -18,12 +18,7 @@ use crate::prepare::PrepareJobKind;
 use parity_scale_codec::{Decode, Encode};
 use polkadot_parachain_primitives::primitives::ValidationCodeHash;
 use polkadot_primitives::ExecutorParams;
-use std::{
-	cmp::{Eq, PartialEq},
-	fmt,
-	sync::Arc,
-	time::Duration,
-};
+use std::{fmt, sync::Arc, time::Duration};
 
 /// A struct that carries the exhaustive set of data to prepare an artifact out of plain
 /// Wasm binary

polkadot/node/core/pvf/common/src/worker/mod.rs

@@ -18,10 +18,13 @@
 
 pub mod security;
 
-use crate::{framed_recv_blocking, SecurityStatus, WorkerHandshake, LOG_TARGET};
+use crate::{
+	framed_recv_blocking, framed_send_blocking, SecurityStatus, WorkerHandshake, LOG_TARGET,
+};
 use cpu_time::ProcessTime;
 use futures::never::Never;
-use parity_scale_codec::Decode;
+use nix::{errno::Errno, sys::resource::Usage};
+use parity_scale_codec::{Decode, Encode};
 use std::{
 	any::Any,
 	fmt::{self},
@@ -58,8 +61,6 @@ macro_rules! decl_worker_main {
 
 			$crate::sp_tracing::try_init_simple();
 
-			let worker_pid = std::process::id();
-
 			let args = std::env::args().collect::<Vec<_>>();
 			if args.len() == 1 {
 				print_help($expected_command);
@@ -548,6 +549,81 @@ fn recv_worker_handshake(stream: &mut UnixStream) -> io::Result<WorkerHandshake>
 	Ok(worker_handshake)
 }
 
+/// Calculate the total CPU time from the given `usage` structure, returned from
+/// [`nix::sys::resource::getrusage`], and calculates the total CPU time spent, including both user
+/// and system time.
+///
+/// # Arguments
+///
+/// - `rusage`: Contains resource usage information.
+///
+/// # Returns
+///
+/// Returns a `Duration` representing the total CPU time.
+pub fn get_total_cpu_usage(rusage: Usage) -> Duration {
+	let micros = (((rusage.user_time().tv_sec() + rusage.system_time().tv_sec()) * 1_000_000) +
+		(rusage.system_time().tv_usec() + rusage.user_time().tv_usec()) as i64) as u64;
+
+	return Duration::from_micros(micros)
+}
+
+/// Get a job response.
+pub fn recv_child_response<T>(
+	received_data: &mut io::BufReader<&[u8]>,
+	context: &'static str,
+) -> io::Result<T>
+where
+	T: Decode,
+{
+	let response_bytes = framed_recv_blocking(received_data)?;
+	T::decode(&mut response_bytes.as_slice()).map_err(|e| {
+		io::Error::new(
+			io::ErrorKind::Other,
+			format!("{} pvf recv_child_response: decode error: {}", context, e),
+		)
+	})
+}
+
+pub fn send_result<T, E>(
+	stream: &mut UnixStream,
+	result: Result<T, E>,
+	worker_info: &WorkerInfo,
+) -> io::Result<()>
+where
+	T: std::fmt::Debug,
+	E: std::fmt::Debug + std::fmt::Display,
+	Result<T, E>: Encode,
+{
+	if let Err(ref err) = result {
+		gum::warn!(
+			target: LOG_TARGET,
+			?worker_info,
+			"worker: error occurred: {}",
+			err
+		);
+	}
+	gum::trace!(
+		target: LOG_TARGET,
+		?worker_info,
+		"worker: sending result to host: {:?}",
+		result
+	);
+
+	framed_send_blocking(stream, &result.encode()).map_err(|err| {
+		gum::warn!(
+			target: LOG_TARGET,
+			?worker_info,
+			"worker: error occurred sending result to host: {}",
+			err
+		);
+		err
+	})
+}
+
+pub fn stringify_errno(context: &'static str, errno: Errno) -> String {
+	format!("{}: {}: {}", context, errno, io::Error::last_os_error())
+}
+
 /// Functionality related to threads spawned by the workers.
 ///
 /// The motivation for this module is to coordinate worker threads without using async Rust.

polkadot/node/core/pvf/execute-worker/src/lib.rs

@@ -16,6 +16,9 @@
 
 //! Contains the logic for executing PVFs. Used by the polkadot-execute-worker binary.
 
+#![deny(unused_crate_dependencies)]
+#![warn(missing_docs)]
+
 pub use polkadot_node_core_pvf_common::{
 	error::ExecuteError, executor_interface::execute_artifact,
 };
@@ -36,11 +39,12 @@ use nix::{
 use parity_scale_codec::{Decode, Encode};
 use polkadot_node_core_pvf_common::{
 	error::InternalValidationError,
-	execute::{Handshake, JobError, JobResponse, JobResult, WorkerResponse},
+	execute::{Handshake, JobError, JobResponse, JobResult, WorkerError, WorkerResponse},
 	executor_interface::params_to_wasmtime_semantics,
 	framed_recv_blocking, framed_send_blocking,
 	worker::{
-		cpu_time_monitor_loop, pipe2_cloexec, run_worker, stringify_panic_payload,
+		cpu_time_monitor_loop, get_total_cpu_usage, pipe2_cloexec, recv_child_response, run_worker,
+		send_result, stringify_errno, stringify_panic_payload,
 		thread::{self, WaitOutcome},
 		PipeFd, WorkerInfo, WorkerKind,
 	},
@@ -93,8 +97,14 @@ fn recv_request(stream: &mut UnixStream) -> io::Result<(Vec<u8>, Duration)> {
 	Ok((params, execution_timeout))
 }
 
-fn send_response(stream: &mut UnixStream, response: WorkerResponse) -> io::Result<()> {
-	framed_send_blocking(stream, &response.encode())
+/// Sends an error to the host and returns the original error wrapped in `io::Error`.
+macro_rules! map_and_send_err {
+	($error:expr, $err_constructor:expr, $stream:expr, $worker_info:expr) => {{
+		let err: WorkerError = $err_constructor($error.to_string()).into();
+		let io_err = io::Error::new(io::ErrorKind::Other, err.to_string());
+		let _ = send_result::<WorkerResponse, WorkerError>($stream, Err(err), $worker_info);
+		io_err
+	}};
 }
 
 /// The entrypoint that the spawned execute worker should start with.
@@ -110,8 +120,6 @@ fn send_response(stream: &mut UnixStream, response: WorkerResponse) -> io::Resul
 ///   check is not necessary.
 ///
 /// - `worker_version`: see above
-///
-/// - `security_status`: contains the detected status of security features.
 pub fn worker_entrypoint(
 	socket_path: PathBuf,
 	worker_dir_path: PathBuf,
@@ -127,13 +135,28 @@ pub fn worker_entrypoint(
 		|mut stream, worker_info, security_status| {
 			let artifact_path = worker_dir::execute_artifact(&worker_info.worker_dir_path);
 
-			let Handshake { executor_params } = recv_execute_handshake(&mut stream)?;
+			let Handshake { executor_params } =
+				recv_execute_handshake(&mut stream).map_err(|e| {
+					map_and_send_err!(
+						e,
+						InternalValidationError::HostCommunication,
+						&mut stream,
+						worker_info
+					)
+				})?;
 
 			let executor_params: Arc<ExecutorParams> = Arc::new(executor_params);
 			let execute_thread_stack_size = max_stack_size(&executor_params);
 
 			loop {
-				let (params, execution_timeout) = recv_request(&mut stream)?;
+				let (params, execution_timeout) = recv_request(&mut stream).map_err(|e| {
+					map_and_send_err!(
+						e,
+						InternalValidationError::HostCommunication,
+						&mut stream,
+						worker_info
+					)
+				})?;
 				gum::debug!(
 					target: LOG_TARGET,
 					?worker_info,
@@ -143,27 +166,34 @@ pub fn worker_entrypoint(
 				);
 
 				// Get the artifact bytes.
-				let compiled_artifact_blob = match std::fs::read(&artifact_path) {
-					Ok(bytes) => bytes,
-					Err(err) => {
-						let response = WorkerResponse::InternalError(
-							InternalValidationError::CouldNotOpenFile(err.to_string()),
-						);
-						send_response(&mut stream, response)?;
-						continue
-					},
-				};
+				let compiled_artifact_blob = std::fs::read(&artifact_path).map_err(|e| {
+					map_and_send_err!(
+						e,
+						InternalValidationError::CouldNotOpenFile,
+						&mut stream,
+						worker_info
+					)
+				})?;
 
-				let (pipe_read_fd, pipe_write_fd) = pipe2_cloexec()?;
+				let (pipe_read_fd, pipe_write_fd) = pipe2_cloexec().map_err(|e| {
+					map_and_send_err!(
+						e,
+						InternalValidationError::CouldNotCreatePipe,
+						&mut stream,
+						worker_info
+					)
+				})?;
 
-				let usage_before = match nix::sys::resource::getrusage(UsageWho::RUSAGE_CHILDREN) {
-					Ok(usage) => usage,
-					Err(errno) => {
-						let response = internal_error_from_errno("getrusage before", errno);
-						send_response(&mut stream, response)?;
-						continue
-					},
-				};
+				let usage_before = nix::sys::resource::getrusage(UsageWho::RUSAGE_CHILDREN)
+					.map_err(|errno| {
+						let e = stringify_errno("getrusage before", errno);
+						map_and_send_err!(
+							e,
+							InternalValidationError::Kernel,
+							&mut stream,
+							worker_info
+						)
+					})?;
 				let stream_fd = stream.as_raw_fd();
 
 				let compiled_artifact_blob = Arc::new(compiled_artifact_blob);
@@ -222,7 +252,7 @@ pub fn worker_entrypoint(
 					"worker: sending result to host: {:?}",
 					result
 				);
-				send_response(&mut stream, result)?;
+				send_result(&mut stream, result, worker_info)?;
 			}
 		},
 	);
@@ -270,7 +300,7 @@ fn handle_clone(
 	worker_info: &WorkerInfo,
 	have_unshare_newuser: bool,
 	usage_before: Usage,
-) -> io::Result<WorkerResponse> {
+) -> io::Result<Result<WorkerResponse, WorkerError>> {
 	use polkadot_node_core_pvf_common::worker::security;
 
 	// SAFETY: new process is spawned within a single threaded process. This invariant
@@ -301,7 +331,8 @@ fn handle_clone(
 			usage_before,
 			execution_timeout,
 		),
-		Err(security::clone::Error::Clone(errno)) => Ok(internal_error_from_errno("clone", errno)),
+		Err(security::clone::Error::Clone(errno)) =>
+			Ok(Err(internal_error_from_errno("clone", errno))),
 	}
 }
 
@@ -316,7 +347,7 @@ fn handle_fork(
 	execute_worker_stack_size: usize,
 	worker_info: &WorkerInfo,
 	usage_before: Usage,
-) -> io::Result<WorkerResponse> {
+) -> io::Result<Result<WorkerResponse, WorkerError>> {
 	// SAFETY: new process is spawned within a single threaded process. This invariant
 	// is enforced by tests.
 	match unsafe { nix::unistd::fork() } {
@@ -338,7 +369,7 @@ fn handle_fork(
 			usage_before,
 			execution_timeout,
 		),
-		Err(errno) => Ok(internal_error_from_errno("fork", errno)),
+		Err(errno) => Ok(Err(internal_error_from_errno("fork", errno))),
 	}
 }
 
@@ -483,11 +514,11 @@ fn handle_parent_process(
 	job_pid: Pid,
 	usage_before: Usage,
 	timeout: Duration,
-) -> io::Result<WorkerResponse> {
+) -> io::Result<Result<WorkerResponse, WorkerError>> {
 	// the read end will wait until all write ends have been closed,
 	// this drop is necessary to avoid deadlock
 	if let Err(errno) = nix::unistd::close(pipe_write_fd) {
-		return Ok(internal_error_from_errno("closing pipe write fd", errno));
+		return Ok(Err(internal_error_from_errno("closing pipe write fd", errno)));
 	};
 
 	// SAFETY: pipe_read_fd is an open and owned file descriptor at this point.
@@ -512,7 +543,7 @@ fn handle_parent_process(
 
 	let usage_after = match nix::sys::resource::getrusage(UsageWho::RUSAGE_CHILDREN) {
 		Ok(usage) => usage,
-		Err(errno) => return Ok(internal_error_from_errno("getrusage after", errno)),
+		Err(errno) => return Ok(Err(internal_error_from_errno("getrusage after", errno))),
 	};
 
 	// Using `getrusage` is needed to check whether child has timedout since we cannot rely on
@@ -530,32 +561,25 @@ fn handle_parent_process(
 			cpu_tv.as_millis(),
 			timeout.as_millis(),
 		);
-		return Ok(WorkerResponse::JobTimedOut)
+		return Ok(Err(WorkerError::JobTimedOut))
 	}
 
 	match status {
 		Ok(WaitStatus::Exited(_, exit_status)) => {
 			let mut reader = io::BufReader::new(received_data.as_slice());
-			let result = match recv_child_response(&mut reader) {
-				Ok(result) => result,
-				Err(err) => return Ok(WorkerResponse::JobError(err.to_string())),
-			};
+			let result = recv_child_response(&mut reader, "execute")?;
 
 			match result {
-				Ok(JobResponse::Ok { result_descriptor }) => {
+				Ok(job_response) => {
 					// The exit status should have been zero if no error occurred.
 					if exit_status != 0 {
-						return Ok(WorkerResponse::JobError(format!(
-							"unexpected exit status: {}",
-							exit_status
-						)))
+						return Ok(Err(WorkerError::JobError(JobError::UnexpectedExitStatus(
+							exit_status,
+						))));
 					}
 
-					Ok(WorkerResponse::Ok { result_descriptor, duration: cpu_tv })
+					Ok(Ok(WorkerResponse { job_response, duration: cpu_tv }))
 				},
-				Ok(JobResponse::InvalidCandidate(err)) => Ok(WorkerResponse::InvalidCandidate(err)),
-				Ok(JobResponse::RuntimeConstruction(err)) =>
-					Ok(WorkerResponse::RuntimeConstruction(err)),
 				Err(job_error) => {
 					gum::warn!(
 						target: LOG_TARGET,
@@ -565,9 +589,9 @@ fn handle_parent_process(
 						job_error,
 					);
 					if matches!(job_error, JobError::TimedOut) {
-						Ok(WorkerResponse::JobTimedOut)
+						Ok(Err(WorkerError::JobTimedOut))
 					} else {
-						Ok(WorkerResponse::JobError(job_error.to_string()))
+						Ok(Err(WorkerError::JobError(job_error.into())))
 					}
 				},
 			}
@@ -576,50 +600,21 @@ fn handle_parent_process(
 		//
 		// The job gets SIGSYS on seccomp violations, but this signal may have been sent for some
 		// other reason, so we still need to check for seccomp violations elsewhere.
-		Ok(WaitStatus::Signaled(_pid, signal, _core_dump)) => Ok(WorkerResponse::JobDied {
+		Ok(WaitStatus::Signaled(_pid, signal, _core_dump)) => Ok(Err(WorkerError::JobDied {
 			err: format!("received signal: {signal:?}"),
 			job_pid: job_pid.as_raw(),
-		}),
-		Err(errno) => Ok(internal_error_from_errno("waitpid", errno)),
+		})),
+		Err(errno) => Ok(Err(internal_error_from_errno("waitpid", errno))),
 
 		// It is within an attacker's power to send an unexpected exit status. So we cannot treat
 		// this as an internal error (which would make us abstain), but must vote against.
-		Ok(unexpected_wait_status) => Ok(WorkerResponse::JobDied {
+		Ok(unexpected_wait_status) => Ok(Err(WorkerError::JobDied {
 			err: format!("unexpected status from wait: {unexpected_wait_status:?}"),
 			job_pid: job_pid.as_raw(),
-		}),
+		})),
 	}
 }
 
-/// Calculate the total CPU time from the given `usage` structure, returned from
-/// [`nix::sys::resource::getrusage`], and calculates the total CPU time spent, including both user
-/// and system time.
-///
-/// # Arguments
-///
-/// - `rusage`: Contains resource usage information.
-///
-/// # Returns
-///
-/// Returns a `Duration` representing the total CPU time.
-fn get_total_cpu_usage(rusage: Usage) -> Duration {
-	let micros = (((rusage.user_time().tv_sec() + rusage.system_time().tv_sec()) * 1_000_000) +
-		(rusage.system_time().tv_usec() + rusage.user_time().tv_usec()) as i64) as u64;
-
-	return Duration::from_micros(micros)
-}
-
-/// Get a job response.
-fn recv_child_response(received_data: &mut io::BufReader<&[u8]>) -> io::Result<JobResult> {
-	let response_bytes = framed_recv_blocking(received_data)?;
-	JobResult::decode(&mut response_bytes.as_slice()).map_err(|e| {
-		io::Error::new(
-			io::ErrorKind::Other,
-			format!("execute pvf recv_child_response: decode error: {}", e),
-		)
-	})
-}
-
 /// Write a job response to the pipe and exit process after.
 ///
 /// # Arguments
@@ -638,15 +633,10 @@ fn send_child_response(pipe_write: &mut PipeFd, response: JobResult) -> ! {
 	}
 }
 
-fn internal_error_from_errno(context: &'static str, errno: Errno) -> WorkerResponse {
-	WorkerResponse::InternalError(InternalValidationError::Kernel(format!(
-		"{}: {}: {}",
-		context,
-		errno,
-		io::Error::last_os_error()
-	)))
+fn internal_error_from_errno(context: &'static str, errno: Errno) -> WorkerError {
+	WorkerError::InternalError(InternalValidationError::Kernel(stringify_errno(context, errno)))
 }
 
 fn job_error_from_errno(context: &'static str, errno: Errno) -> JobResult {
-	Err(JobError::Kernel(format!("{}: {}: {}", context, errno, io::Error::last_os_error())))
+	Err(JobError::Kernel(stringify_errno(context, errno)))
 }

polkadot/node/core/pvf/prepare-worker/src/lib.rs

@@ -26,7 +26,6 @@ const LOG_TARGET: &str = "parachain::pvf-prepare-worker";
 use crate::memory_stats::max_rss_stat::{extract_max_rss_stat, get_max_rss_thread};
 #[cfg(any(target_os = "linux", feature = "jemalloc-allocator"))]
 use crate::memory_stats::memory_tracker::{get_memory_tracker_loop_stats, memory_tracker_loop};
-use libc;
 use nix::{
 	errno::Errno,
 	sys::{
@@ -48,7 +47,8 @@ use polkadot_node_core_pvf_common::{
 	prepare::{MemoryStats, PrepareJobKind, PrepareStats, PrepareWorkerSuccess},
 	pvf::PvfPrepData,
 	worker::{
-		cpu_time_monitor_loop, run_worker, stringify_panic_payload,
+		cpu_time_monitor_loop, get_total_cpu_usage, recv_child_response, run_worker, send_result,
+		stringify_errno, stringify_panic_payload,
 		thread::{self, spawn_worker_thread, WaitOutcome},
 		WorkerKind,
 	},
@@ -117,11 +117,6 @@ fn recv_request(stream: &mut UnixStream) -> io::Result<PvfPrepData> {
 	Ok(pvf)
 }
 
-/// Send a worker response.
-fn send_response(stream: &mut UnixStream, result: PrepareWorkerResult) -> io::Result<()> {
-	framed_send_blocking(stream, &result.encode())
-}
-
 fn start_memory_tracking(fd: RawFd, limit: Option<isize>) {
 	unsafe {
 		// SAFETY: Inside the failure handler, the allocator is locked and no allocations or
@@ -178,8 +173,6 @@ fn end_memory_tracking() -> isize {
 ///
 /// - `worker_version`: see above
 ///
-/// - `security_status`: contains the detected status of security features.
-///
 /// # Flow
 ///
 /// This runs the following in a loop:
@@ -233,8 +226,9 @@ pub fn worker_entrypoint(
 				let usage_before = match nix::sys::resource::getrusage(UsageWho::RUSAGE_CHILDREN) {
 					Ok(usage) => usage,
 					Err(errno) => {
-						let result = Err(error_from_errno("getrusage before", errno));
-						send_response(&mut stream, result)?;
+						let result: PrepareWorkerResult =
+							Err(error_from_errno("getrusage before", errno));
+						send_result(&mut stream, result, worker_info)?;
 						continue
 					},
 				};
@@ -294,7 +288,7 @@ pub fn worker_entrypoint(
 					"worker: sending result to host: {:?}",
 					result
 				);
-				send_response(&mut stream, result)?;
+				send_result(&mut stream, result, worker_info)?;
 			}
 		},
 	);
@@ -666,7 +660,7 @@ fn handle_parent_process(
 	match status {
 		Ok(WaitStatus::Exited(_pid, exit_status)) => {
 			let mut reader = io::BufReader::new(received_data.as_slice());
-			let result = recv_child_response(&mut reader)
+			let result = recv_child_response(&mut reader, "prepare")
 				.map_err(|err| PrepareError::JobError(err.to_string()))?;
 
 			match result {
@@ -726,35 +720,6 @@ fn handle_parent_process(
 	}
 }
 
-/// Calculate the total CPU time from the given `usage` structure, returned from
-/// [`nix::sys::resource::getrusage`], and calculates the total CPU time spent, including both user
-/// and system time.
-///
-/// # Arguments
-///
-/// - `rusage`: Contains resource usage information.
-///
-/// # Returns
-///
-/// Returns a `Duration` representing the total CPU time.
-fn get_total_cpu_usage(rusage: Usage) -> Duration {
-	let micros = (((rusage.user_time().tv_sec() + rusage.system_time().tv_sec()) * 1_000_000) +
-		(rusage.system_time().tv_usec() + rusage.user_time().tv_usec()) as i64) as u64;
-
-	return Duration::from_micros(micros)
-}
-
-/// Get a job response.
-fn recv_child_response(received_data: &mut io::BufReader<&[u8]>) -> io::Result<JobResult> {
-	let response_bytes = framed_recv_blocking(received_data)?;
-	JobResult::decode(&mut response_bytes.as_slice()).map_err(|e| {
-		io::Error::new(
-			io::ErrorKind::Other,
-			format!("prepare pvf recv_child_response: decode error: {:?}", e),
-		)
-	})
-}
-
 /// Write a job response to the pipe and exit process after.
 ///
 /// # Arguments
@@ -774,7 +739,7 @@ fn send_child_response(pipe_write: &mut PipeFd, response: JobResult) -> ! {
 }
 
 fn error_from_errno(context: &'static str, errno: Errno) -> PrepareError {
-	PrepareError::Kernel(format!("{}: {}: {}", context, errno, io::Error::last_os_error()))
+	PrepareError::Kernel(stringify_errno(context, errno))
 }
 
 type JobResult = Result<JobResponse, PrepareError>;

polkadot/node/core/pvf/src/execute/queue.rs

@@ -16,7 +16,7 @@
 
 //! A queue that handles requests for PVF execution.
 
-use super::worker_interface::Outcome;
+use super::worker_interface::{Error as WorkerInterfaceError, Response as WorkerInterfaceResponse};
 use crate::{
 	artifacts::{ArtifactId, ArtifactPathId},
 	host::ResultSender,
@@ -30,7 +30,10 @@ use futures::{
 	stream::{FuturesUnordered, StreamExt as _},
 	Future, FutureExt,
 };
-use polkadot_node_core_pvf_common::SecurityStatus;
+use polkadot_node_core_pvf_common::{
+	execute::{JobResponse, WorkerError, WorkerResponse},
+	SecurityStatus,
+};
 use polkadot_primitives::{ExecutorParams, ExecutorParamsHash};
 use slotmap::HopSlotMap;
 use std::{
@@ -133,7 +136,12 @@ impl Workers {
 
 enum QueueEvent {
 	Spawn(IdleWorker, WorkerHandle, ExecuteJob),
-	StartWork(Worker, Outcome, ArtifactId, ResultSender),
+	StartWork(
+		Worker,
+		Result<WorkerInterfaceResponse, WorkerInterfaceError>,
+		ArtifactId,
+		ResultSender,
+	),
 }
 
 type Mux = FuturesUnordered<BoxFuture<'static, QueueEvent>>;
@@ -340,23 +348,34 @@ fn handle_worker_spawned(
 async fn handle_job_finish(
 	queue: &mut Queue,
 	worker: Worker,
-	outcome: Outcome,
+	worker_result: Result<WorkerInterfaceResponse, WorkerInterfaceError>,
 	artifact_id: ArtifactId,
 	result_tx: ResultSender,
 ) {
-	let (idle_worker, result, duration, sync_channel) = match outcome {
-		Outcome::Ok { result_descriptor, duration, idle_worker } => {
+	let (idle_worker, result, duration, sync_channel) = match worker_result {
+		Ok(WorkerInterfaceResponse {
+			worker_response:
+				WorkerResponse { job_response: JobResponse::Ok { result_descriptor }, duration },
+			idle_worker,
+		}) => {
 			// TODO: propagate the soft timeout
 
 			(Some(idle_worker), Ok(result_descriptor), Some(duration), None)
 		},
-		Outcome::InvalidCandidate { err, idle_worker } => (
+		Ok(WorkerInterfaceResponse {
+			worker_response: WorkerResponse { job_response: JobResponse::InvalidCandidate(err), .. },
+			idle_worker,
+		}) => (
 			Some(idle_worker),
 			Err(ValidationError::Invalid(InvalidCandidate::WorkerReportedInvalid(err))),
 			None,
 			None,
 		),
-		Outcome::RuntimeConstruction { err, idle_worker } => {
+		Ok(WorkerInterfaceResponse {
+			worker_response:
+				WorkerResponse { job_response: JobResponse::RuntimeConstruction(err), .. },
+			idle_worker,
+		}) => {
 			// The task for artifact removal is executed concurrently with
 			// the message to the host on the execution result.
 			let (result_tx, result_rx) = oneshot::channel();
@@ -376,27 +395,31 @@ async fn handle_job_finish(
 				Some(result_rx),
 			)
 		},
-		Outcome::InternalError { err } => (None, Err(ValidationError::Internal(err)), None, None),
+
+		Err(WorkerInterfaceError::InternalError(err)) |
+		Err(WorkerInterfaceError::WorkerError(WorkerError::InternalError(err))) =>
+			(None, Err(ValidationError::Internal(err)), None, None),
 		// Either the worker or the job timed out. Kill the worker in either case. Treated as
 		// definitely-invalid, because if we timed out, there's no time left for a retry.
-		Outcome::HardTimeout =>
+		Err(WorkerInterfaceError::HardTimeout) |
+		Err(WorkerInterfaceError::WorkerError(WorkerError::JobTimedOut)) =>
 			(None, Err(ValidationError::Invalid(InvalidCandidate::HardTimeout)), None, None),
 		// "Maybe invalid" errors (will retry).
-		Outcome::WorkerIntfErr => (
+		Err(WorkerInterfaceError::CommunicationErr(_err)) => (
 			None,
 			Err(ValidationError::PossiblyInvalid(PossiblyInvalidError::AmbiguousWorkerDeath)),
 			None,
 			None,
 		),
-		Outcome::JobDied { err } => (
+		Err(WorkerInterfaceError::WorkerError(WorkerError::JobDied { err, .. })) => (
 			None,
 			Err(ValidationError::PossiblyInvalid(PossiblyInvalidError::AmbiguousJobDeath(err))),
 			None,
 			None,
 		),
-		Outcome::JobError { err } => (
+		Err(WorkerInterfaceError::WorkerError(WorkerError::JobError(err))) => (
 			None,
-			Err(ValidationError::PossiblyInvalid(PossiblyInvalidError::JobError(err))),
+			Err(ValidationError::PossiblyInvalid(PossiblyInvalidError::JobError(err.to_string()))),
 			None,
 			None,
 		),
@@ -543,14 +566,14 @@ fn assign(queue: &mut Queue, worker: Worker, job: ExecuteJob) {
 	queue.mux.push(
 		async move {
 			let _timer = execution_timer;
-			let outcome = super::worker_interface::start_work(
+			let result = super::worker_interface::start_work(
 				idle,
 				job.artifact.clone(),
 				job.exec_timeout,
 				job.params,
 			)
 			.await;
-			QueueEvent::StartWork(worker, outcome, job.artifact.id, job.result_tx)
+			QueueEvent::StartWork(worker, result, job.artifact.id, job.result_tx)
 		}
 		.boxed(),
 	);

polkadot/node/core/pvf/src/execute/worker_interface.rs

@@ -29,10 +29,9 @@ use futures_timer::Delay;
 use parity_scale_codec::{Decode, Encode};
 use polkadot_node_core_pvf_common::{
 	error::InternalValidationError,
-	execute::{Handshake, WorkerResponse},
+	execute::{Handshake, WorkerError, WorkerResponse},
 	worker_dir, SecurityStatus,
 };
-use polkadot_parachain_primitives::primitives::ValidationResult;
 use polkadot_primitives::ExecutorParams;
 use std::{path::Path, time::Duration};
 use tokio::{io, net::UnixStream};
@@ -69,7 +68,8 @@ pub async fn spawn(
 			gum::warn!(
 				target: LOG_TARGET,
 				worker_pid = %idle_worker.pid,
-				%err
+				"failed to send a handshake to the spawned worker: {}",
+				error
 			);
 			err
 		})?;
@@ -78,39 +78,40 @@ pub async fn spawn(
 
 /// Outcome of PVF execution.
 ///
-/// If the idle worker token is not returned, it means the worker must be terminated.
-pub enum Outcome {
-	/// PVF execution completed successfully and the result is returned. The worker is ready for
-	/// another job.
-	Ok { result_descriptor: ValidationResult, duration: Duration, idle_worker: IdleWorker },
-	/// The candidate validation failed. It may be for example because the wasm execution triggered
-	/// a trap. Errors related to the preparation process are not expected to be encountered by the
-	/// execution workers.
-	InvalidCandidate { err: String, idle_worker: IdleWorker },
-	/// The error is probably transient. It may be for example
-	/// because the artifact was prepared with a Wasmtime version different from the version
-	/// in the current execution environment.
-	RuntimeConstruction { err: String, idle_worker: IdleWorker },
+/// PVF execution completed and the result is returned. The worker is ready for
+/// another job.
+pub struct Response {
+	/// The response (valid/invalid) from the worker.
+	pub worker_response: WorkerResponse,
+	/// Returning the idle worker token means the worker can be reused.
+	pub idle_worker: IdleWorker,
+}
+/// The idle worker token is not returned for any of these cases, meaning the worker must be
+/// terminated.
+///
+/// NOTE: Errors related to the preparation process are not expected to be encountered by the
+/// execution workers.
+#[derive(thiserror::Error, Debug)]
+pub enum Error {
 	/// The execution time exceeded the hard limit. The worker is terminated.
+	#[error("The communication with the worker exceeded the hard limit")]
 	HardTimeout,
 	/// An I/O error happened during communication with the worker. This may mean that the worker
 	/// process already died. The token is not returned in any case.
-	WorkerIntfErr,
-	/// The job process has died. We must kill the worker just in case.
-	///
-	/// We cannot treat this as an internal error because malicious code may have caused this.
-	JobDied { err: String },
-	/// An unexpected error occurred in the job process.
-	///
-	/// Because malicious code can cause a job error, we must not treat it as an internal error.
-	JobError { err: String },
+	#[error("An I/O error happened during communication with the worker: {0}")]
+	CommunicationErr(#[from] io::Error),
+	/// The worker reported an error (can be from itself or from the job). The worker should not be
+	/// reused.
+	#[error("The worker reported an error: {0}")]
+	WorkerError(#[from] WorkerError),
 
 	/// An internal error happened during the validation. Such an error is most likely related to
 	/// some transient glitch.
 	///
 	/// Should only ever be used for errors independent of the candidate and PVF. Therefore it may
 	/// be a problem with the worker, so we terminate it.
-	InternalError { err: InternalValidationError },
+	#[error("An internal error occurred: {0}")]
+	InternalError(#[from] InternalValidationError),
 }
 
 /// Given the idle token of a worker and parameters of work, communicates with the worker and
@@ -123,7 +124,7 @@ pub async fn start_work(
 	artifact: ArtifactPathId,
 	execution_timeout: Duration,
 	validation_params: Vec<u8>,
-) -> Outcome {
+) -> Result<Response, Error> {
 	let IdleWorker { mut stream, pid, worker_dir } = worker;
 
 	gum::debug!(
@@ -136,16 +137,18 @@ pub async fn start_work(
 	);
 
 	with_worker_dir_setup(worker_dir, pid, &artifact.path, |worker_dir| async move {
-		if let Err(error) = send_request(&mut stream, &validation_params, execution_timeout).await {
-			gum::warn!(
-				target: LOG_TARGET,
-				worker_pid = %pid,
-				validation_code_hash = ?artifact.id.code_hash,
-				?error,
-				"failed to send an execute request",
-			);
-			return Outcome::WorkerIntfErr
-		}
+		send_request(&mut stream, &validation_params, execution_timeout).await.map_err(
+			|error| {
+				gum::warn!(
+					target: LOG_TARGET,
+					worker_pid = %pid,
+					validation_code_hash = ?artifact.id.code_hash,
+					"failed to send an execute request: {}",
+					error,
+				);
+				Error::InternalError(InternalValidationError::HostCommunication(error.to_string()))
+			},
+		)?;
 
 		// We use a generous timeout here. This is in addition to the one in the child process, in
 		// case the child stalls. We have a wall clock timeout here in the host, but a CPU timeout
@@ -153,12 +156,12 @@ pub async fn start_work(
 		// load, but the CPU resources of the child can only be measured from the parent after the
 		// child process terminates.
 		let timeout = execution_timeout * JOB_TIMEOUT_WALL_CLOCK_FACTOR;
-		let response = futures::select! {
-			response = recv_response(&mut stream).fuse() => {
-				match response {
-					Ok(response) =>
-						handle_response(
-							response,
+		let worker_result = futures::select! {
+			worker_result = recv_result(&mut stream).fuse() => {
+				match worker_result {
+					Ok(result) =>
+						handle_result(
+							result,
 							pid,
 							execution_timeout,
 						)
@@ -168,11 +171,11 @@ pub async fn start_work(
 							target: LOG_TARGET,
 							worker_pid = %pid,
 							validation_code_hash = ?artifact.id.code_hash,
-							?error,
-							"failed to recv an execute response",
+							"failed to recv an execute result: {}",
+							error,
 						);
 
-						return Outcome::WorkerIntfErr
+						return Err(Error::CommunicationErr(error))
 					},
 				}
 			},
@@ -183,29 +186,16 @@ pub async fn start_work(
 					validation_code_hash = ?artifact.id.code_hash,
 					"execution worker exceeded lenient timeout for execution, child worker likely stalled",
 				);
-				WorkerResponse::JobTimedOut
+				return Err(Error::HardTimeout)
 			},
 		};
 
-		match response {
-			WorkerResponse::Ok { result_descriptor, duration } => Outcome::Ok {
-				result_descriptor,
-				duration,
+		match worker_result {
+			Ok(worker_response) => Ok(Response {
+				worker_response,
 				idle_worker: IdleWorker { stream, pid, worker_dir },
-			},
-			WorkerResponse::InvalidCandidate(err) => Outcome::InvalidCandidate {
-				err,
-				idle_worker: IdleWorker { stream, pid, worker_dir },
-			},
-			WorkerResponse::RuntimeConstruction(err) => Outcome::RuntimeConstruction {
-				err,
-				idle_worker: IdleWorker { stream, pid, worker_dir },
-			},
-			WorkerResponse::JobTimedOut => Outcome::HardTimeout,
-			WorkerResponse::JobDied { err, job_pid: _ } => Outcome::JobDied { err },
-			WorkerResponse::JobError(err) => Outcome::JobError { err },
-
-			WorkerResponse::InternalError(err) => Outcome::InternalError { err },
+			}),
+			Err(worker_error) => Err(worker_error.into()),
 		}
 	})
 	.await
@@ -215,12 +205,12 @@ pub async fn start_work(
 ///
 /// Here we know the artifact exists, but is still located in a temporary file which will be cleared
 /// by [`with_worker_dir_setup`].
-async fn handle_response(
-	response: WorkerResponse,
+async fn handle_result(
+	worker_result: Result<WorkerResponse, WorkerError>,
 	worker_pid: u32,
 	execution_timeout: Duration,
-) -> WorkerResponse {
-	if let WorkerResponse::Ok { duration, .. } = response {
+) -> Result<WorkerResponse, WorkerError> {
+	if let Ok(WorkerResponse { duration, .. }) = worker_result {
 		if duration > execution_timeout {
 			// The job didn't complete within the timeout.
 			gum::warn!(
@@ -232,11 +222,11 @@ async fn handle_response(
 			);
 
 			// Return a timeout error.
-			return WorkerResponse::JobTimedOut
+			return Err(WorkerError::JobTimedOut)
 		}
 	}
 
-	response
+	worker_result
 }
 
 /// Create a temporary file for an artifact in the worker cache, execute the given future/closure
@@ -249,9 +239,9 @@ async fn with_worker_dir_setup<F, Fut>(
 	pid: u32,
 	artifact_path: &Path,
 	f: F,
-) -> Outcome
+) -> Result<Response, Error>
 where
-	Fut: futures::Future<Output = Outcome>,
+	Fut: futures::Future<Output = Result<Response, Error>>,
 	F: FnOnce(WorkerDir) -> Fut,
 {
 	// Cheaply create a hard link to the artifact. The artifact is always at a known location in the
@@ -263,16 +253,14 @@ where
 			target: LOG_TARGET,
 			worker_pid = %pid,
 			?worker_dir,
-			"failed to clear worker cache after the job: {:?}",
+			"failed to clear worker cache after the job: {}",
 			err,
 		);
-		return Outcome::InternalError {
-			err: InternalValidationError::CouldNotCreateLink(format!("{:?}", err)),
-		}
+		return Err(InternalValidationError::CouldNotCreateLink(format!("{:?}", err)).into());
 	}
 
 	let worker_dir_path = worker_dir.path().to_owned();
-	let outcome = f(worker_dir).await;
+	let result = f(worker_dir).await;
 
 	// Try to clear the worker dir.
 	if let Err(err) = clear_worker_dir_path(&worker_dir_path) {
@@ -283,15 +271,14 @@ where
 			"failed to clear worker cache after the job: {:?}",
 			err,
 		);
-		return Outcome::InternalError {
-			err: InternalValidationError::CouldNotClearWorkerDir {
-				err: format!("{:?}", err),
-				path: worker_dir_path.to_str().map(String::from),
-			},
+		return Err(InternalValidationError::CouldNotClearWorkerDir {
+			err: format!("{:?}", err),
+			path: worker_dir_path.to_str().map(String::from),
 		}
+		.into())
 	}
 
-	outcome
+	result
 }
 
 /// Sends a handshake with information specific to the execute worker.
@@ -308,12 +295,12 @@ async fn send_request(
 	framed_send(stream, &execution_timeout.encode()).await
 }
 
-async fn recv_response(stream: &mut UnixStream) -> io::Result<WorkerResponse> {
-	let response_bytes = framed_recv(stream).await?;
-	WorkerResponse::decode(&mut response_bytes.as_slice()).map_err(|e| {
+async fn recv_result(stream: &mut UnixStream) -> io::Result<Result<WorkerResponse, WorkerError>> {
+	let result_bytes = framed_recv(stream).await?;
+	Result::<WorkerResponse, WorkerError>::decode(&mut result_bytes.as_slice()).map_err(|e| {
 		io::Error::new(
 			io::ErrorKind::Other,
-			format!("execute pvf recv_response: decode error: {:?}", e),
+			format!("execute pvf recv_result: decode error: {:?}", e),
 		)
 	})
 }

polkadot/node/core/pvf/src/host.rs

@@ -959,10 +959,7 @@ pub(crate) mod tests {
 	use crate::{artifacts::generate_artifact_path, PossiblyInvalidError};
 	use assert_matches::assert_matches;
 	use futures::future::BoxFuture;
-	use polkadot_node_core_pvf_common::{
-		error::PrepareError,
-		prepare::{PrepareStats, PrepareSuccess},
-	};
+	use polkadot_node_core_pvf_common::prepare::PrepareStats;
 
 	const TEST_EXECUTION_TIMEOUT: Duration = Duration::from_secs(3);
 	pub(crate) const TEST_PREPARATION_TIMEOUT: Duration = Duration::from_secs(30);