From bc81fa2e48cbe6a71c08ee6b9e72f869eca5660b Mon Sep 17 00:00:00 2001
From: Sebastien Bourdeauducq <sb@m-labs.hk>
Date: Tue, 9 Jun 2020 13:03:08 +0800
Subject: [PATCH] handle recursive RPC return values

---
 src/runtime/src/comms.rs | 47 ++++++++++++++++++++++------------------
 src/runtime/src/main.rs  |  1 -
 2 files changed, 26 insertions(+), 22 deletions(-)

diff --git a/src/runtime/src/comms.rs b/src/runtime/src/comms.rs
index e7078041..05a77f5d 100644
--- a/src/runtime/src/comms.rs
+++ b/src/runtime/src/comms.rs
@@ -125,10 +125,10 @@ async fn read_string(stream: &TcpStream, max_length: usize) -> Result<String> {
     Ok(String::from_utf8(bytes).map_err(|err| Error::Utf8Error(err.utf8_error()))?)
 }
 
-async fn handle_run_kernel(stream: &TcpStream, control: &mut kernel::Control) -> Result<()> {
-    control.tx.async_send(kernel::Message::StartRequest).await;
+async fn handle_run_kernel(stream: &TcpStream, control: &Rc<RefCell<kernel::Control>>) -> Result<()> {
+    control.borrow_mut().tx.async_send(kernel::Message::StartRequest).await;
     loop {
-        let reply = control.rx.async_recv().await;
+        let reply = control.borrow_mut().rx.async_recv().await;
         match *reply {
             kernel::Message::RpcSend { is_async, data } => {
                 write_header(stream, Reply::RPCRequest).await?;
@@ -139,29 +139,34 @@ async fn handle_run_kernel(stream: &TcpStream, control: &mut kernel::Control) ->
                     match host_request {
                         Request::RPCReply => {
                             let tag = read_bytes(stream, 512).await?;
-                            let rpc_recv_request = control.rx.async_recv().await;
-                            let slot = if let kernel::Message::RpcRecvRequest(slot) = *rpc_recv_request {
-                                slot
-                            } else {
-                                panic!(
-                                    "expected root value slot from core1, not {:?}", rpc_recv_request);
+                            let slot = match *control.borrow_mut().rx.async_recv().await {
+                                kernel::Message::RpcRecvRequest(slot) => slot,
+                                other => panic!("expected root value slot from core1, not {:?}", other),
                             };
-                            rpc::recv_return(stream, &tag, slot, &async move |size| -> *mut () {
-                                if size == 0 {
-                                    // Don't try to allocate zero-length values, as RpcRecvReply(0) is
-                                    // used to terminate the kernel-side receive loop.
-                                    return 0 as *mut ()
+                            rpc::recv_return(stream, &tag, slot, &|size| {
+                                let control = control.clone();
+                                async move {
+                                    if size == 0 {
+                                        // Don't try to allocate zero-length values, as RpcRecvReply(0) is
+                                        // used to terminate the kernel-side receive loop.
+                                        0 as *mut ()
+                                    } else {
+                                        let mut control = control.borrow_mut();
+                                        control.tx.async_send(kernel::Message::RpcRecvReply(Ok(size))).await;
+                                        match *control.rx.async_recv().await {
+                                            kernel::Message::RpcRecvRequest(slot) => slot,
+                                            other => panic!("expected nested value slot from kernel CPU, not {:?}", other),
+                                        }
+                                    }
                                 }
-                                unimplemented!();
                             }).await?;
-                            control.tx.async_send(kernel::Message::RpcRecvReply(Ok(0))).await;
+                            control.borrow_mut().tx.async_send(kernel::Message::RpcRecvReply(Ok(0))).await;
                         },
                         Request::RPCException => {
-                            let rpc_recv_request = control.rx.async_recv().await;
-                            match *rpc_recv_request {
+                            let mut control = control.borrow_mut();
+                            match *control.rx.async_recv().await {
                                 kernel::Message::RpcRecvRequest(_) => (),
-                                _ => panic!(
-                                    "expected (ignored) root value slot from kernel CPU, not {:?}", rpc_recv_request),
+                                other => panic!("expected (ignored) root value slot from kernel CPU, not {:?}", other),
                             }
                             let name =     read_string(stream, 16384).await?;
                             let message =  read_string(stream, 16384).await?;
@@ -227,7 +232,7 @@ async fn handle_connection(stream: &TcpStream, control: Rc<RefCell<kernel::Contr
                 }
             },
             Request::RunKernel => {
-                handle_run_kernel(stream, &mut control.borrow_mut()).await?;
+                handle_run_kernel(stream, &control).await?;
             },
             _ => {
                 error!("unexpected request from host: {:?}", request);
diff --git a/src/runtime/src/main.rs b/src/runtime/src/main.rs
index f9508191..48522dfa 100644
--- a/src/runtime/src/main.rs
+++ b/src/runtime/src/main.rs
@@ -2,7 +2,6 @@
 #![no_main]
 #![recursion_limit="1024"]  // for futures_util::select!
 #![feature(llvm_asm)]
-#![feature(async_closure)]
 
 extern crate alloc;