Base dummy waker on RawWaker to avoid allocations

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.toml

@@ -13,7 +13,7 @@ name = "stack_overflow"
 harness = false
 
 [dependencies]
-bootloader = { version = "0.8.0", features = ["map_physical_memory"]}
+bootloader = { version = "0.9.0", features = ["map_physical_memory"], path = "../../../bootloader/master"}
 volatile = "0.2.6"
 spin = "0.5.2"
 x86_64 = "0.9.6"

src/task/simple_executor.rs

@@ -1,6 +1,9 @@
 use super::Task;
-use alloc::{collections::VecDeque, sync::Arc, task::Wake};
-use core::task::{Context, Poll, Waker};
+use alloc::collections::VecDeque;
+use core::{
+    ptr,
+    task::{Context, Poll, RawWaker, RawWakerVTable, Waker},
+};
 
 pub struct SimpleExecutor {
     task_queue: VecDeque<Task>,
@@ -19,7 +22,7 @@ impl SimpleExecutor {
 
     pub fn run(&mut self) {
         while let Some(mut task) = self.task_queue.pop_front() {
-            let waker = DummyWaker.to_waker();
+            let waker = waker();
             let mut context = Context::from_waker(&waker);
             match task.poll(&mut context) {
                 Poll::Ready(()) => {} // task done
@@ -29,16 +32,18 @@ impl SimpleExecutor {
     }
 }
 
-struct DummyWaker;
-
-impl Wake for DummyWaker {
-    fn wake(self: Arc<Self>) {
-        // do nothing
-    }
+fn raw_waker() -> RawWaker {
+    fn no_op(_: *const ()) {}
+    fn clone(_: *const ()) -> RawWaker {
+        raw_waker()
     }
 
-impl DummyWaker {
-    fn to_waker(self) -> Waker {
-        Waker::from(Arc::new(self))
+    RawWaker::new(
+        ptr::null(),
+        &RawWakerVTable::new(clone, no_op, no_op, no_op),
+    )
 }
+
+fn waker() -> Waker {
+    unsafe { Waker::from_raw(raw_waker()) }
 }