From ae07c05db4e3d961700ea7d2216c6f1d10970726 Mon Sep 17 00:00:00 2001
From: pca006132 <john.lck40@gmail.com>
Date: Tue, 1 Sep 2020 09:44:34 +0800
Subject: [PATCH] runtime: optimize for speed and fix deadlock

The previous method of taking the channel could cause deadlock, we now
use semaphore to signal if the channel is available instead of busy
polling the mutex.
---
 src/Cargo.lock                    | 10 +++++-----
 src/Cargo.toml                    |  2 +-
 src/runtime/src/kernel/control.rs |  3 ++-
 src/runtime/src/kernel/core1.rs   |  2 ++
 src/runtime/src/kernel/mod.rs     |  3 ++-
 5 files changed, 12 insertions(+), 8 deletions(-)

diff --git a/src/Cargo.lock b/src/Cargo.lock
index 3217e606..d42c75c5 100644
--- a/src/Cargo.lock
+++ b/src/Cargo.lock
@@ -187,7 +187,7 @@ dependencies = [
 [[package]]
 name = "libasync"
 version = "0.0.0"
-source = "git+https://git.m-labs.hk/M-Labs/zynq-rs.git#a73df780d0d0e757738f27feac162904f5bf93f9"
+source = "git+https://git.m-labs.hk/M-Labs/zynq-rs.git#157439bc88cbb18bb40009428acf1fdee800e32e"
 dependencies = [
  "embedded-hal",
  "libcortex_a9",
@@ -199,7 +199,7 @@ dependencies = [
 [[package]]
 name = "libboard_zynq"
 version = "0.0.0"
-source = "git+https://git.m-labs.hk/M-Labs/zynq-rs.git#a73df780d0d0e757738f27feac162904f5bf93f9"
+source = "git+https://git.m-labs.hk/M-Labs/zynq-rs.git#157439bc88cbb18bb40009428acf1fdee800e32e"
 dependencies = [
  "bit_field",
  "embedded-hal",
@@ -233,7 +233,7 @@ dependencies = [
 [[package]]
 name = "libcortex_a9"
 version = "0.0.0"
-source = "git+https://git.m-labs.hk/M-Labs/zynq-rs.git#a73df780d0d0e757738f27feac162904f5bf93f9"
+source = "git+https://git.m-labs.hk/M-Labs/zynq-rs.git#157439bc88cbb18bb40009428acf1fdee800e32e"
 dependencies = [
  "bit_field",
  "libregister",
@@ -249,7 +249,7 @@ checksum = "c7d73b3f436185384286bd8098d17ec07c9a7d2388a6599f824d8502b529702a"
 [[package]]
 name = "libregister"
 version = "0.0.0"
-source = "git+https://git.m-labs.hk/M-Labs/zynq-rs.git#a73df780d0d0e757738f27feac162904f5bf93f9"
+source = "git+https://git.m-labs.hk/M-Labs/zynq-rs.git#157439bc88cbb18bb40009428acf1fdee800e32e"
 dependencies = [
  "bit_field",
  "vcell",
@@ -259,7 +259,7 @@ dependencies = [
 [[package]]
 name = "libsupport_zynq"
 version = "0.0.0"
-source = "git+https://git.m-labs.hk/M-Labs/zynq-rs.git#a73df780d0d0e757738f27feac162904f5bf93f9"
+source = "git+https://git.m-labs.hk/M-Labs/zynq-rs.git#157439bc88cbb18bb40009428acf1fdee800e32e"
 dependencies = [
  "compiler_builtins",
  "libboard_zynq",
diff --git a/src/Cargo.toml b/src/Cargo.toml
index e68c9bdf..4bc1f769 100644
--- a/src/Cargo.toml
+++ b/src/Cargo.toml
@@ -24,7 +24,7 @@ overflow-checks = false
 panic = "abort"
 debug = true
 codegen-units = 1
-opt-level = 's'
+opt-level = 2
 lto = true
 
 [patch.crates-io]
diff --git a/src/runtime/src/kernel/control.rs b/src/runtime/src/kernel/control.rs
index 91fefa31..3ffe1319 100644
--- a/src/runtime/src/kernel/control.rs
+++ b/src/runtime/src/kernel/control.rs
@@ -1,7 +1,7 @@
 use libcortex_a9::sync_channel::{Sender, Receiver};
 use libsupport_zynq::boot::Core1;
 
-use super::{CHANNEL_0TO1, CHANNEL_1TO0, INIT_LOCK, Message};
+use super::{CHANNEL_0TO1, CHANNEL_1TO0, CHANNEL_SEM, INIT_LOCK, Message};
 use crate::irq::restart_core1;
 
 use core::mem::{forget, replace};
@@ -12,6 +12,7 @@ pub struct Control {
 }
 
 fn get_channels() -> (Sender<'static, Message>, Receiver<'static, Message>) {
+    CHANNEL_SEM.wait();
     let mut core0_tx = None;
     while core0_tx.is_none() {
         core0_tx = CHANNEL_0TO1.lock().take();
diff --git a/src/runtime/src/kernel/core1.rs b/src/runtime/src/kernel/core1.rs
index ec2e27cf..94e0e242 100644
--- a/src/runtime/src/kernel/core1.rs
+++ b/src/runtime/src/kernel/core1.rs
@@ -20,6 +20,7 @@ use super::{
     rpc::rpc_send_async,
     INIT_LOCK,
     CHANNEL_0TO1, CHANNEL_1TO0,
+    CHANNEL_SEM,
     KERNEL_CHANNEL_0TO1, KERNEL_CHANNEL_1TO0,
     KERNEL_IMAGE,
     Message,
@@ -159,6 +160,7 @@ pub fn main_core1() {
     }
     *CHANNEL_0TO1.lock() = Some(core0_tx);
     *CHANNEL_1TO0.lock() = Some(core0_rx);
+    CHANNEL_SEM.signal();
 
     // set on load, cleared on start
     let mut loaded_kernel = None;
diff --git a/src/runtime/src/kernel/mod.rs b/src/runtime/src/kernel/mod.rs
index e06a6e18..c3bb1fbe 100644
--- a/src/runtime/src/kernel/mod.rs
+++ b/src/runtime/src/kernel/mod.rs
@@ -1,7 +1,7 @@
 use core::ptr;
 use alloc::{vec::Vec, string::String};
 
-use libcortex_a9::{mutex::Mutex, sync_channel};
+use libcortex_a9::{mutex::Mutex, sync_channel, semaphore::Semaphore};
 use crate::eh_artiq;
 
 mod control;
@@ -48,6 +48,7 @@ pub enum Message {
 
 static CHANNEL_0TO1: Mutex<Option<sync_channel::Sender<'static, Message>>> = Mutex::new(None);
 static CHANNEL_1TO0: Mutex<Option<sync_channel::Receiver<'static, Message>>> = Mutex::new(None);
+static CHANNEL_SEM: Semaphore = Semaphore::new(0, 1);
 
 static mut KERNEL_CHANNEL_0TO1: Option<sync_channel::Receiver<'static, Message>> = None;
 static mut KERNEL_CHANNEL_1TO0: Option<sync_channel::Sender<'static, Message>> = None;