Add Spinlock type

kernel/src/sys/acpica_osl.rs

@@ -15,7 +15,7 @@ use crate::{
 };
 
 use super::{
-    sync::{lock_kernel, unlock_kernel},
+    scheduler::SCHEDULER_LOCK,
     task::{CURRENT_TASK, MULTITASKING_ENABLED},
 };
 
@@ -68,11 +68,11 @@ extern "C" fn AcpiOsGetThreadId() -> UINT64 {
         return 1;
     }
     let task_id;
-    lock_kernel();
+    SCHEDULER_LOCK.lock();
     {
         task_id = CURRENT_TASK.lock().as_ref().unwrap().id;
     }
-    unlock_kernel();
+    SCHEDULER_LOCK.unlock();
     task_id as UINT64
 }
 #[no_mangle]

kernel/src/sys/hpet.rs

@@ -13,8 +13,7 @@ use crate::cpu::paging::map_physical;
 use super::{
     early_acpi::EarlyACPIHandler,
     ioapic::register_isa_irq_handler,
-    scheduler::{schedule_task, yield_task},
-    sync::{lock_kernel, unlock_kernel},
+    scheduler::{schedule_task, yield_task, SCHEDULER_LOCK},
     task::{Task, TaskState, CURRENT_TASK, MULTITASKING_ENABLED},
 };
 
@@ -65,23 +64,25 @@ fn handler() {
         EARLY_SLEEP.store(false, Ordering::Relaxed);
     }
     if MULTITASKING_ENABLED.load(Ordering::Relaxed) {
-        lock_kernel();
-        let mut sleeping_list = SLEEPING_LIST.lock();
-        let current_time = get_current_time();
-        while let Some(task) = sleeping_list.first() {
-            if task.sleep_until_us <= current_time {
-                let mut task = sleeping_list.remove(0);
-                task.sleep_until_us = 0;
-                task.task_state = TaskState::Ready;
-                schedule_task(task);
-            } else {
-                break;
+        SCHEDULER_LOCK.lock();
+        {
+            let mut sleeping_list = SLEEPING_LIST.lock();
+            let current_time = get_current_time();
+            while let Some(task) = sleeping_list.first() {
+                if task.sleep_until_us <= current_time {
+                    let mut task = sleeping_list.remove(0);
+                    task.sleep_until_us = 0;
+                    task.task_state = TaskState::Ready;
+                    schedule_task(task);
+                } else {
+                    break;
+                }
+            }
+            if let Some(task) = sleeping_list.first() {
+                schedule_hpet_interrupt(task.sleep_until_us);
             }
         }
-        if let Some(task) = sleeping_list.first() {
-            schedule_hpet_interrupt(task.sleep_until_us);
-        }
-        unlock_kernel();
+        SCHEDULER_LOCK.unlock();
     }
 }
 fn get_current_time() -> usize {
@@ -91,14 +92,14 @@ fn get_current_time() -> usize {
 }
 pub fn sleep(us: usize) {
     if MULTITASKING_ENABLED.load(Ordering::Relaxed) {
-        lock_kernel();
+        SCHEDULER_LOCK.lock();
         {
             let mut _current_task = CURRENT_TASK.lock();
             let current_task = _current_task.as_mut().unwrap();
             current_task.sleep_until_us = get_current_time() + us;
             current_task.task_state = TaskState::Sleeping;
         }
-        unlock_kernel();
+        SCHEDULER_LOCK.unlock();
         yield_task();
     } else {
         EARLY_SLEEP.store(true, Ordering::Relaxed);

kernel/src/sys/scheduler.rs

@@ -7,18 +7,19 @@ use crate::cpu::isr::ISRState;
 
 use super::{
     lapic::schedule_timer_interrupt,
-    sync::{lock_kernel, unlock_kernel, IN_ISR_HANDLER, KERNEL_LOCKED},
+    sync::{Spinlock, IN_ISR_HANDLER, LOCKS_HELD},
     task::{switch_task, Task, TaskState, CURRENT_TASK, MULTITASKING_ENABLED},
 };
 
 static SCHEDULER_LIST: Mutex<VecDeque<Task>> = Mutex::new(VecDeque::new());
 pub static IDLE_TASK: Mutex<Option<Task>> = Mutex::new(None);
+pub static SCHEDULER_LOCK: Spinlock = Spinlock::new();
 
 pub fn scheduler(state: &mut ISRState) {
     if !MULTITASKING_ENABLED.load(Ordering::Relaxed) {
         return;
     }
-    lock_kernel();
+    SCHEDULER_LOCK.lock();
     let mut switch_to_task = None;
     {
         let mut scheduler_list = SCHEDULER_LIST.lock();
@@ -29,7 +30,7 @@ pub fn scheduler(state: &mut ISRState) {
     }
     if let Some(task) = switch_to_task {
         switch_task(state, task);
-        unlock_kernel();
+        SCHEDULER_LOCK.unlock();
         return;
     }
     let mut switch_idle = false;
@@ -43,21 +44,17 @@ pub fn scheduler(state: &mut ISRState) {
     if switch_idle {
         switch_task(state, IDLE_TASK.lock().take().unwrap());
     }
-    unlock_kernel();
+    SCHEDULER_LOCK.unlock();
 }
 pub fn schedule_task(task: Task) {
-    lock_kernel();
-    {
-        let mut scheduler_list = SCHEDULER_LIST.lock();
-        if scheduler_list.is_empty() {
-            schedule_timer_interrupt();
-        }
-        scheduler_list.push_back(task);
+    let mut scheduler_list = SCHEDULER_LIST.lock();
+    if scheduler_list.is_empty() {
+        schedule_timer_interrupt();
     }
-    unlock_kernel();
+    scheduler_list.push_back(task);
 }
 pub fn yield_task() {
-    if IN_ISR_HANDLER.load(Ordering::Relaxed) || KERNEL_LOCKED.load(Ordering::Relaxed) > 0 {
+    if IN_ISR_HANDLER.load(Ordering::Relaxed) || LOCKS_HELD.load(Ordering::Relaxed) > 0 {
         panic!("Unsafe use of yield_task()");
     }
     unsafe {

kernel/src/sys/sync.rs

@@ -5,31 +5,42 @@ use kernel_common::instructions::{cli, sti};
 use spin::Mutex;
 
 use super::{
-    scheduler::{schedule_task, yield_task},
+    scheduler::{schedule_task, yield_task, SCHEDULER_LOCK},
     task::{Task, TaskState, CURRENT_TASK},
 };
 
-pub static KERNEL_LOCKED: AtomicUsize = AtomicUsize::new(0);
 pub static IN_ISR_HANDLER: AtomicBool = AtomicBool::new(false);
+pub static LOCKS_HELD: AtomicUsize = AtomicUsize::new(0);
 
 pub struct Semaphore {
     max_count: usize,
     current_count: usize,
     blocked_list: VecDeque<Task>,
 }
-
-pub fn lock_kernel() {
-    cli();
-    KERNEL_LOCKED.fetch_add(1, Ordering::Relaxed);
+pub struct Spinlock {
+    locked: AtomicBool,
 }
-pub fn unlock_kernel() {
-    KERNEL_LOCKED.fetch_sub(1, Ordering::Relaxed);
-    if !IN_ISR_HANDLER.load(Ordering::Relaxed) && KERNEL_LOCKED.load(Ordering::Relaxed) == 0 {
-        unsafe {
-            sti();
+
+impl Spinlock {
+    pub const fn new() -> Self {
+        Self { locked: AtomicBool::new(false) }
+    }
+    pub fn lock(&self) {
+        cli();
+        while !self.locked.compare_exchange(false, true, Ordering::Relaxed, Ordering::Relaxed).is_ok() {}
+        LOCKS_HELD.fetch_add(1, Ordering::Relaxed);
+    }
+    pub fn unlock(&self) {
+        self.locked.store(false, Ordering::Relaxed);
+        LOCKS_HELD.fetch_sub(1, Ordering::Relaxed);
+        if !IN_ISR_HANDLER.load(Ordering::Relaxed) && LOCKS_HELD.load(Ordering::Relaxed) == 0 {
+            unsafe {
+                sti();
+            }
         }
     }
 }
+
 pub fn create_semaphore(max_count: usize) -> Arc<Mutex<Semaphore>> {
     Arc::new(Mutex::new(Semaphore {
         max_count,
@@ -39,7 +50,7 @@ pub fn create_semaphore(max_count: usize) -> Arc<Mutex<Semaphore>> {
 }
 pub fn lock_semaphore(semaphore: Arc<Mutex<Semaphore>>, count: usize) {
     loop {
-        lock_kernel();
+        SCHEDULER_LOCK.lock();
         let mut success = false;
         {
             let mut semaphore = semaphore.lock();
@@ -49,7 +60,7 @@ pub fn lock_semaphore(semaphore: Arc<Mutex<Semaphore>>, count: usize) {
             }
         }
         if success {
-            unlock_kernel();
+            SCHEDULER_LOCK.unlock();
             return;
         }
         {
@@ -59,7 +70,7 @@ pub fn lock_semaphore(semaphore: Arc<Mutex<Semaphore>>, count: usize) {
             current_task.block_on_semaphore = Some(semaphore.clone());
             current_task.semaphore_requested_count = count;
         }
-        unlock_kernel();
+        SCHEDULER_LOCK.unlock();
         yield_task();
     }
 }
@@ -76,7 +87,7 @@ pub fn lock_semaphore_internal(mut task: Task) {
     }
 }
 pub fn unlock_semaphore(semaphore: Arc<Mutex<Semaphore>>, count: usize) {
-    lock_kernel();
+    SCHEDULER_LOCK.lock();
     {
         let mut semaphore = semaphore.lock();
         semaphore.current_count -= count;
@@ -87,5 +98,5 @@ pub fn unlock_semaphore(semaphore: Arc<Mutex<Semaphore>>, count: usize) {
             schedule_task(task);
         }
     }
-    unlock_kernel();
+    SCHEDULER_LOCK.unlock();
 }

kernel/src/sys/task.rs

@@ -10,14 +10,14 @@ use spin::Mutex;
 use crate::{
     cpu::isr::ISRState,
     main,
-    sys::scheduler::{schedule_task, IDLE_TASK},
+    sys::scheduler::{schedule_task, IDLE_TASK, SCHEDULER_LOCK},
 };
 
 use super::{
     hpet::sleep_internal,
     lapic::schedule_timer_interrupt,
     scheduler::yield_task,
-    sync::{lock_kernel, lock_semaphore_internal, unlock_kernel, Semaphore},
+    sync::{lock_semaphore_internal, Semaphore},
 };
 
 #[derive(PartialEq)]
@@ -109,19 +109,19 @@ pub fn create_task(func: fn()) -> Task {
     task
 }
 extern "C" fn task_entry() -> ! {
-    lock_kernel();
+    SCHEDULER_LOCK.lock();
     let func;
     {
         let task = CURRENT_TASK.lock();
         func = task.as_ref().unwrap().initial_func;
     }
-    unlock_kernel();
+    SCHEDULER_LOCK.unlock();
     func();
-    lock_kernel();
+    SCHEDULER_LOCK.lock();
     {
         CURRENT_TASK.lock().as_mut().unwrap().task_state = TaskState::Terminated;
     }
-    unlock_kernel();
+    SCHEDULER_LOCK.unlock();
     yield_task();
     panic!("Failed to terminate task");
 }