Use LinkedList to store WorkItem to avoid additional heap allocation

kernel/src/device/tty/line_discipline.rs

@@ -92,11 +92,11 @@ impl LineDiscipline {
     pub fn new(send_signal: LdiscSignalSender) -> Arc<Self> {
         Arc::new_cyclic(move |line_ref: &Weak<LineDiscipline>| {
             let line_discipline = line_ref.clone();
-            let work_item = Arc::new(WorkItem::new(Box::new(move || {
+            let work_item = WorkItem::new(Box::new(move || {
                 if let Some(line_discipline) = line_discipline.upgrade() {
                     line_discipline.send_signal_after();
                 }
-            })));
+            }));
             Self {
                 current_line: SpinLock::new(CurrentLine::default()),
                 read_buffer: SpinLock::new(RingBuffer::new(BUFFER_CAPACITY)),

kernel/src/process/process/timer_manager.rs

@@ -106,7 +106,7 @@ fn create_process_timer_callback(process_ref: &Weak<Process>) -> impl Fn() + Clo
     };
 
     let work_func = Box::new(sent_signal);
-    let work_item = Arc::new(WorkItem::new(work_func));
+    let work_item = WorkItem::new(work_func);
 
     move || {
         submit_work_item(

kernel/src/syscall/timer_create.rs

@@ -95,7 +95,7 @@ pub fn sys_timer_create(
     };
 
     let work_func = sent_signal;
-    let work_item = Arc::new(WorkItem::new(work_func));
+    let work_item = WorkItem::new(work_func);
     let func = move || {
         submit_work_item(
             work_item.clone(),

kernel/src/thread/work_queue/mod.rs

@@ -64,9 +64,10 @@
 //!
 //! ```
 
+use intrusive_collections::linked_list::LinkedList;
 use ostd::cpu::{CpuId, CpuSet};
 use spin::Once;
-use work_item::WorkItem;
+use work_item::{WorkItem, WorkItemAdapter};
 use worker_pool::WorkerPool;
 
 use crate::prelude::*;
@@ -86,7 +87,7 @@ pub fn submit_work_func<F>(work_func: F, work_priority: WorkPriority)
 where
     F: Fn() + Send + Sync + 'static,
 {
-    let work_item = Arc::new(WorkItem::new(Box::new(work_func)));
+    let work_item = WorkItem::new(Box::new(work_func));
     submit_work_item(work_item, work_priority);
 }
 
@@ -112,7 +113,7 @@ pub struct WorkQueue {
 }
 
 struct WorkQueueInner {
-    pending_work_items: Vec<Arc<WorkItem>>,
+    pending_work_items: LinkedList<WorkItemAdapter>,
 }
 
 impl WorkQueue {
@@ -122,7 +123,7 @@ impl WorkQueue {
         let queue = Arc::new(WorkQueue {
             worker_pool: worker_pool.clone(),
             inner: SpinLock::new(WorkQueueInner {
-                pending_work_items: Vec::new(),
+                pending_work_items: LinkedList::new(WorkItemAdapter::NEW),
             }),
         });
         worker_pool
@@ -141,7 +142,7 @@ impl WorkQueue {
             .disable_irq()
             .lock()
             .pending_work_items
-            .push(work_item);
+            .push_back(work_item);
 
         true
     }
@@ -150,12 +151,16 @@ impl WorkQueue {
     /// the calling worker is located.
     fn dequeue(&self, request_cpu: CpuId) -> Option<Arc<WorkItem>> {
         let mut inner = self.inner.disable_irq().lock();
-        let index = inner
+        let mut cursor = inner.pending_work_items.front_mut();
-            .pending_work_items
+        while let Some(item) = cursor.get() {
-            .iter()
+            if item.is_valid_cpu(request_cpu) {
-            .position(|item| item.is_valid_cpu(request_cpu))?;
+                return cursor.remove();
-        let item = inner.pending_work_items.remove(index);
+            }
-        Some(item)
+
+            cursor.move_next();
+        }
+
+        None
     }
 
     fn has_pending_work_items(&self, request_cpu: CpuId) -> bool {

kernel/src/thread/work_queue/work_item.rs

@@ -4,6 +4,7 @@
 
 use core::sync::atomic::{AtomicBool, Ordering};
 
+use intrusive_collections::{intrusive_adapter, LinkedListAtomicLink};
 use ostd::cpu::{CpuId, CpuSet};
 
 use crate::prelude::*;
@@ -13,16 +14,20 @@ pub struct WorkItem {
     work_func: Box<dyn Fn() + Send + Sync>,
     cpu_affinity: CpuSet,
     was_pending: AtomicBool,
+    link: LinkedListAtomicLink,
 }
 
+intrusive_adapter!(pub(super) WorkItemAdapter = Arc<WorkItem>: WorkItem { link: LinkedListAtomicLink });
+
 impl WorkItem {
-    pub fn new(work_func: Box<dyn Fn() + Send + Sync>) -> WorkItem {
+    pub fn new(work_func: Box<dyn Fn() + Send + Sync>) -> Arc<WorkItem> {
         let cpu_affinity = CpuSet::new_full();
-        WorkItem {
+        Arc::new(WorkItem {
             work_func,
             cpu_affinity,
             was_pending: AtomicBool::new(false),
-        }
+            link: LinkedListAtomicLink::new(),
+        })
     }
 
     pub fn cpu_affinity(&self) -> &CpuSet {