Switch back to official nightly

The Wake trait is based on Arc, which leads to deallocation on wakes. Since interrupts should not (de)allocate, this can lead to a deadlock.

Cargo.lock

@@ -24,6 +24,7 @@ version = "0.1.0"
 dependencies = [
  "bootloader",
  "conquer-once",
+ "cooked-waker",
  "crossbeam-queue",
  "futures-util",
  "lazy_static",
@@ -38,7 +39,9 @@ dependencies = [
 
 [[package]]
 name = "bootloader"
-version = "0.8.8"
+version = "0.8.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "152a28c753e229e037e910b4cd4cd16a90c53dd9a67fd751fa304b4b4a03970c"
 
 [[package]]
 name = "cfg-if"
@@ -61,6 +64,27 @@ version = "0.2.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "654fb2472cc369d311c547103a1fa81d467bef370ae7a0680f65939895b1182a"
 
+[[package]]
+name = "cooked-waker"
+version = "1.0.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b0032e8be0680b63daf14b0fd7fd57f85fd6897951e110b041d32e839a831914"
+dependencies = [
+ "cooked-waker-derive",
+ "stowaway",
+]
+
+[[package]]
+name = "cooked-waker-derive"
+version = "1.0.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "74ded02b04a8ff53ea7328cd71297cde598bee70d165ad92512bdb7e20be9d74"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
 [[package]]
 name = "cpuio"
 version = "0.2.0"
@@ -158,6 +182,24 @@ version = "0.1.0-alpha.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "5894c618ce612a3fa23881b152b608bafb8c56cfc22f434a3ba3120b40f7b587"
 
+[[package]]
+name = "proc-macro2"
+version = "1.0.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6c09721c6781493a2a492a96b5a5bf19b65917fe6728884e7c44dd0c60ca3435"
+dependencies = [
+ "unicode-xid",
+]
+
+[[package]]
+name = "quote"
+version = "1.0.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2bdc6c187c65bca4260c9011c9e3132efe4909da44726bad24cf7572ae338d7f"
+dependencies = [
+ "proc-macro2",
+]
+
 [[package]]
 name = "scopeguard"
 version = "1.1.0"
@@ -179,6 +221,23 @@ dependencies = [
  "lock_api",
 ]
 
+[[package]]
+name = "stowaway"
+version = "1.1.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "32b13d61e782863c0eaeeaf7e8e580dc956a625851fd2fb73e5e92db9601c891"
+
+[[package]]
+name = "syn"
+version = "1.0.17"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0df0eb663f387145cab623dea85b09c2c5b4b0aef44e945d928e682fce71bb03"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "unicode-xid",
+]
+
 [[package]]
 name = "uart_16550"
 version = "0.2.4"
@@ -189,6 +248,12 @@ dependencies = [
  "x86_64",
 ]
 
+[[package]]
+name = "unicode-xid"
+version = "0.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "826e7639553986605ec5979c7dd957c7895e93eabed50ab2ffa7f6128a75097c"
+
 [[package]]
 name = "volatile"
 version = "0.2.6"

Cargo.toml

@@ -13,7 +13,7 @@ name = "stack_overflow"
 harness = false
 
 [dependencies]
-bootloader = { version = "0.8.0", features = ["map_physical_memory"]}
+bootloader = { version = "0.8.8", features = ["map_physical_memory"]}
 volatile = "0.2.6"
 spin = "0.5.2"
 x86_64 = "0.9.6"
@@ -21,6 +21,7 @@ uart_16550 = "0.2.0"
 pic8259_simple = "0.1.1"
 pc-keyboard = "0.5.0"
 linked_list_allocator = "0.8.0"
+cooked-waker = "1.0.2"
 
 [dependencies.lazy_static]
 version = "1.0"
@@ -38,7 +39,7 @@ default-features = false
 [dependencies.futures-util]
 version = "0.3.4"
 default-features = false
-features = ["alloc", "async-await"]
+features = ["alloc"]
 
 [package.metadata.bootimage]
 test-args = [

src/interrupts.rs

@@ -80,28 +80,11 @@ extern "x86-interrupt" fn timer_interrupt_handler(_stack_frame: &mut InterruptSt
 }
 
 extern "x86-interrupt" fn keyboard_interrupt_handler(_stack_frame: &mut InterruptStackFrame) {
-    use pc_keyboard::{layouts, DecodedKey, HandleControl, Keyboard, ScancodeSet1};
-    use spin::Mutex;
     use x86_64::instructions::port::Port;
 
-    lazy_static! {
-        static ref KEYBOARD: Mutex<Keyboard<layouts::Us104Key, ScancodeSet1>> = Mutex::new(
-            Keyboard::new(layouts::Us104Key, ScancodeSet1, HandleControl::Ignore)
-        );
-    }
-
-    let mut keyboard = KEYBOARD.lock();
     let mut port = Port::new(0x60);
-
     let scancode: u8 = unsafe { port.read() };
-    if let Ok(Some(key_event)) = keyboard.add_byte(scancode) {
+    crate::task::keyboard::add_scancode(scancode);
-        if let Some(key) = keyboard.process_keyevent(key_event) {
-            match key {
-                DecodedKey::Unicode(character) => print!("{}", character),
-                DecodedKey::RawKey(key) => print!("{:?}", key),
-            }
-        }
-    }
 
     unsafe {
         PICS.lock()

src/lib.rs

@@ -6,8 +6,6 @@
 #![feature(const_fn)]
 #![feature(alloc_layout_extra)]
 #![feature(const_in_array_repeat_expressions)]
-#![feature(wake_trait)]
-#![feature(async_closure)]
 #![test_runner(crate::test_runner)]
 #![reexport_test_harness_main = "test_main"]
 

src/main.rs

@@ -15,7 +15,7 @@ entry_point!(kernel_main);
 fn kernel_main(boot_info: &'static BootInfo) -> ! {
     use blog_os::allocator;
     use blog_os::memory::{self, BootInfoFrameAllocator};
-    use blog_os::task::{simple_executor::SimpleExecutor, Task, keyboard};
+    use blog_os::task::{keyboard, simple_executor::SimpleExecutor, Task};
     use x86_64::VirtAddr;
 
     println!("Hello World{}", "!");

src/task/keyboard.rs

@@ -1,11 +1,32 @@
-use conquer_once::spin::OnceCell;
-use crossbeam_queue::ArrayQueue;
-use futures_util::stream::{Stream, StreamExt};
-use core::{pin::Pin, task::{Context, Poll}};
-use pc_keyboard::{layouts, DecodedKey, HandleControl, Keyboard, ScancodeSet1};
 use crate::print;
+use crate::println;
+use conquer_once::spin::OnceCell;
+use core::{
+    pin::Pin,
+    task::{Context, Poll},
+};
+use crossbeam_queue::ArrayQueue;
+use futures_util::stream::StreamExt;
+use futures_util::{stream::Stream, task::AtomicWaker};
+use pc_keyboard::{layouts, DecodedKey, HandleControl, Keyboard, ScancodeSet1};
 
 static SCANCODE_QUEUE: OnceCell<ArrayQueue<u8>> = OnceCell::uninit();
+static WAKER: AtomicWaker = AtomicWaker::new();
+
+/// Called by the keyboard interrupt handler
+///
+/// Must not block or allocate.
+pub(crate) fn add_scancode(scancode: u8) {
+    if let Ok(queue) = SCANCODE_QUEUE.try_get() {
+        if let Err(_) = queue.push(scancode) {
+            println!("WARNING: scancode queue full; dropping keyboard input");
+        } else {
+            WAKER.wake();
+        }
+    } else {
+        println!("WARNING: scancode queue uninitialized");
+    }
+}
 
 pub struct ScancodeStream {
     _private: (),
@@ -13,21 +34,27 @@ pub struct ScancodeStream {
 
 impl ScancodeStream {
     pub fn new() -> Self {
-        SCANCODE_QUEUE.try_init_once(|| ArrayQueue::new(100))
+        SCANCODE_QUEUE
+            .try_init_once(|| ArrayQueue::new(100))
             .expect("ScancodeStream::new should only be called once");
-        ScancodeStream {
+        ScancodeStream { _private: () }
-            _private: (),
-        }
     }
 }
 
 impl Stream for ScancodeStream {
     type Item = u8;
 
-    fn poll_next(self: Pin<&mut Self>, context: &mut Context) -> Poll<Option<u8>> {
+    fn poll_next(self: Pin<&mut Self>, cx: &mut Context) -> Poll<Option<u8>> {
         let queue = SCANCODE_QUEUE
             .try_get()
             .expect("scancode queue not initialized");
+
+        // fast path
+        if let Ok(scancode) = queue.pop() {
+            return Poll::Ready(Some(scancode));
+        }
+
+        WAKER.register(&cx.waker());
         match queue.pop() {
             Ok(scancode) => Poll::Ready(Some(scancode)),
             Err(crossbeam_queue::PopError) => Poll::Pending,

src/task/mod.rs

@@ -19,4 +19,8 @@ impl Task {
     fn poll(&mut self, context: &mut Context) -> Poll<()> {
         self.future.as_mut().poll(context)
     }
+
+    fn id(&self) -> usize {
+        &*self.future as *const _ as *const () as usize
+    }
 }

src/task/simple_executor.rs

@@ -1,15 +1,24 @@
 use super::Task;
-use alloc::{collections::VecDeque, sync::Arc, task::Wake};
+use alloc::{
-use core::task::{Context, Poll, Waker};
+    collections::{BTreeMap, VecDeque},
+    sync::Arc,
+};
+use cooked_waker::IntoWaker;
+use core::task::{Context, Poll};
+use crossbeam_queue::ArrayQueue;
 
 pub struct SimpleExecutor {
     task_queue: VecDeque<Task>,
+    waiting_tasks: BTreeMap<usize, Task>,
+    wake_queue: Arc<ArrayQueue<usize>>,
 }
 
 impl SimpleExecutor {
     pub fn new() -> SimpleExecutor {
         SimpleExecutor {
             task_queue: VecDeque::new(),
+            waiting_tasks: BTreeMap::new(),
+            wake_queue: Arc::new(ArrayQueue::new(100)),
         }
     }
 
@@ -18,27 +27,60 @@ impl SimpleExecutor {
     }
 
     pub fn run(&mut self) {
+        loop {
+            self.handle_wakeups();
+            self.run_ready_tasks();
+        }
+    }
+
+    fn handle_wakeups(&mut self) {
+        while let Ok(task_id) = self.wake_queue.pop() {
+            if let Some(task) = self.waiting_tasks.remove(&task_id) {
+                self.task_queue.push_back(task);
+            }
+        }
+    }
+
+    fn run_ready_tasks(&mut self) {
         while let Some(mut task) = self.task_queue.pop_front() {
-            let waker = DummyWaker.to_waker();
+            let waker = TaskWaker {
+                task_id: task.id(),
+                wake_queue: self.wake_queue.clone(),
+            }
+            .into_waker();
             let mut context = Context::from_waker(&waker);
             match task.poll(&mut context) {
                 Poll::Ready(()) => {} // task done
-                Poll::Pending => self.task_queue.push_back(task),
+                Poll::Pending => {
+                    if self.waiting_tasks.insert(task.id(), task).is_some() {
+                        panic!("Same task inserted into waiting_tasks twice");
+                    }
+                }
             }
         }
     }
 }
 
-struct DummyWaker;
+#[derive(Debug, Clone, IntoWaker)]
+struct TaskWaker {
+    task_id: usize,
+    wake_queue: Arc<ArrayQueue<usize>>,
+}
 
-impl Wake for DummyWaker {
+impl TaskWaker {
-    fn wake(self: Arc<Self>) {
+    fn wake_task(&self) {
-        // do nothing
+        self.wake_queue.push(self.task_id).expect("wake queue full");
     }
 }
 
-impl DummyWaker {
+impl cooked_waker::WakeRef for TaskWaker {
-    fn to_waker(self) -> Waker {
+    fn wake_by_ref(&self) {
-        Waker::from(Arc::new(self))
+        self.wake_task();
+    }
+}
+
+impl cooked_waker::Wake for TaskWaker {
+    fn wake(self) {
+        self.wake_task();
     }
 }