feat(sched): add timer-driven scheduling and wait queues

docs/agents/tasks/04-time-scheduler.md

@@ -57,14 +57,20 @@
 - 已建立 x86 上下文切换入口，保存/恢复 callee-saved 寄存器和栈指针。
 - 已建立线程 trampoline，新线程能从独立内核栈进入自己的入口函数。
 - 已建立协作式 round-robin，两个 kernel thread 能通过 `sched_yield()` 轮转运行。
-- `scripts/check.sh` 已验证 `timer initialized`、`timer tick=1/2/3`、`scheduler initialized`、`kernel thread selftest ok` 和 `thread 1/2` 轮转日志。
+- 已把调度接入 `timer_tick()`，timer tick 会唤醒到期 sleep 线程并触发 round-robin。
+- 已建立 idle thread，所有普通线程 sleep/wait 时由 idle 承接 CPU。
+- 已提供 `sched_sleep()`，线程可以睡眠指定 tick 数并被 timer 唤醒。
+- 已提供 `wait_queue_init()`、`wait_queue_sleep()`、`wait_queue_wake_one()` 和 `wait_queue_wake_all()`。
+- `scripts/check.sh` 已验证 `timer initialized`、`timer tick=1/2/3`、`scheduler initialized`、`kernel thread selftest ok`、timer 驱动线程轮转、`sched_sleep()` 和 wait queue wakeup。
 
 后续扩展：
 
 - 把 IRQ 分发扩展为可注册 handler 的表，而不是只处理 timer。
-- 把协作式调度接入 timer tick，演进为抢占式调度。
-- 建立 `yield()`、`sleep()`、timer wakeup 和 wait queue。
+- 把当前直接在 timer IRQ 内触发调度的路径收敛为更明确的 interrupt-exit reschedule 模型。
+- 建立基础 spinlock 或 interrupt-safe lock。
+- 为 wait queue 增加条件等待、超时等待和状态检查。
+- 为线程退出增加资源回收路径。
 
 下一阶段：
 
-- 继续在 `04-time-scheduler.md` 内推进 timer 驱动的抢占式调度、`sleep()` 和 wait queue。
+- 继续在 `04-time-scheduler.md` 内推进 interrupt-safe lock、线程退出回收和更严格的 interrupt-exit reschedule。

docs/agents/tasks/README.md

@@ -28,7 +28,7 @@
 | `01-early-debug.md` | 基础完成 | 已有 early log 前端、QEMU debug port、COM1 串口和最小 `panic()`。 |
 | `02-cpu-interrupts.md` | 基础完成 | 已有 GDT/TSS/IDT、exception vector 0-31、`trap_frame` 和 invalid opcode 回归测试。 |
 | `03-memory.md` | 基础完成 | 已有最小物理页 allocator、页表 map/unmap/query、page fault 诊断和内核堆。 |
-| `04-time-scheduler.md` | 进行中 | 已有 PIT timer interrupt、通用 tick 计数、kernel thread、内核栈、上下文切换和协作式 round-robin；抢占式调度和等待队列未完成。 |
+| `04-time-scheduler.md` | 进行中 | 已有 PIT timer interrupt、通用 tick、kernel thread、内核栈、上下文切换、timer 驱动 round-robin、sleep 和 wait queue 基础；锁、退出回收和更严格的中断返回调度未完成。 |
 | `05-input-events.md` | 未开始 | 需要输入事件模型和键盘接入。 |
 | `06-storage-vfs.md` | 未开始 | 需要块层、缓存、VFS 和基础文件系统。 |
 | `07-user-mode.md` | 未开始 | 需要 syscall、进程、用户地址空间和 ELF 加载。 |
@@ -36,7 +36,7 @@
 | `09-driver-expansion.md` | 未开始 | 需要设备模型、PCI/ACPI、存储、网络等驱动扩展。 |
 | `10-real-machine.md` | 未开始 | 需要 U 盘真机启动验证和硬件差异记录。 |
 
-当前最合适的下一步仍在 `04-time-scheduler.md` 内：把调度接入 timer tick，演进到抢占式调度，然后做 `sleep()` 和 wait queue。
+当前最合适的下一步仍在 `04-time-scheduler.md` 内：补 interrupt-safe lock、线程退出回收，并把调度路径收敛为更明确的 interrupt-exit reschedule。
 
 ## Linux 级能力缺口路由
 

docs/roadmap.md

@@ -26,6 +26,7 @@
 - timer 基础：已接入 x86 PIC/PIT，timer IRQ 能进入通用 tick 入口。
 - kernel thread 基础：已建立线程对象、内核栈和 run queue。
 - 调度基础：已建立 x86 上下文切换入口和协作式 round-robin。
+- sleep/wait 基础：timer tick 能唤醒 sleep 线程，wait queue 支持 sleep 和 wake。
 - 构建系统已拆成根 Makefile、`arch/x86/Makefile` 和目录 Makefile。
 - `scripts/check.sh` 已验证启动日志、串口日志和 invalid opcode 异常路径，GitHub Actions 已接入。
 - `.clang-format` 已用于强制当前 C 代码风格。
@@ -45,8 +46,9 @@
 
 目标：
 
-- 把调度接入 timer tick，演进到抢占式调度。
-- 建立 `sleep()`、timer wakeup 和 wait queue。
+- 建立 interrupt-safe lock。
+- 建立线程退出资源回收。
+- 把调度路径收敛为更明确的 interrupt-exit reschedule。
 
 ## 任务路由
 

include/tianole/sched.h

@@ -10,9 +10,15 @@ enum thread_state {
 	THREAD_READY,
 	THREAD_RUNNING,
 	THREAD_SLEEPING,
+	THREAD_WAITING,
 	THREAD_DEAD,
 };
 
+struct wait_queue {
+	struct thread *head;
+	struct thread *tail;
+};
+
 struct thread {
 	uint64_t id;
 	enum thread_state state;
@@ -22,7 +28,9 @@ struct thread {
 	void *stack_base;
 	uintptr_t stack_top;
 	size_t stack_size;
+	uint64_t wake_tick;
 	struct thread *next;
+	struct thread *wait_next;
 	char name[32];
 };
 
@@ -30,6 +38,12 @@ void sched_init(void);
 struct thread *kernel_thread_create(
 	const char *name, kernel_thread_entry_t entry, void *arg);
 void sched_start(void) __attribute__((noreturn));
+void sched_tick(uint64_t tick);
 void sched_yield(void);
+void sched_sleep(uint64_t ticks);
+void wait_queue_init(struct wait_queue *queue);
+void wait_queue_sleep(struct wait_queue *queue);
+void wait_queue_wake_one(struct wait_queue *queue);
+void wait_queue_wake_all(struct wait_queue *queue);
 
 #endif

kernel/sched/thread.c

@@ -6,6 +6,7 @@
 #include <tianole/early_log.h>
 #include <tianole/mm.h>
 #include <tianole/sched.h>
+#include <tianole/timer.h>
 
 #define KERNEL_STACK_SIZE (PAGE_SIZE * 4u)
 #define STACK_ALIGNMENT 16u
@@ -16,6 +17,8 @@ static struct thread *current_thread;
 static uintptr_t boot_stack_pointer;
 static uint64_t next_thread_id = 1;
 static int scheduler_ready;
+static int schedule_locked;
+static struct thread *idle_thread;
 
 static void thread_trampoline(void) __attribute__((noreturn));
 
@@ -102,7 +105,9 @@ struct thread *kernel_thread_create(
 	thread->stack_top = align_down_uintptr(stack_top, STACK_ALIGNMENT);
 	thread->stack_pointer = prepare_initial_stack(thread->stack_top);
 	thread->stack_size = KERNEL_STACK_SIZE;
+	thread->wake_tick = 0;
 	thread->next = 0;
+	thread->wait_next = 0;
 	copy_thread_name(thread->name, sizeof(thread->name), name);
 
 	enqueue_thread(thread);
@@ -123,36 +128,60 @@ static struct thread *next_runnable_thread(void)
 
 	thread = start;
 	while (thread != 0) {
-		if (thread->state == THREAD_READY) {
+		if (thread->state == THREAD_READY && thread != idle_thread) {
 			return thread;
 		}
 		thread = thread->next;
 	}
 
 	for (thread = run_queue_head; thread != start; thread = thread->next) {
-		if (thread->state == THREAD_READY) {
+		if (thread->state == THREAD_READY && thread != idle_thread) {
 			return thread;
 		}
 	}
 
+	if (idle_thread != 0 && idle_thread->state == THREAD_READY) {
+		return idle_thread;
+	}
+
 	return 0;
 }
 
+static void wake_sleeping_threads(uint64_t tick)
+{
+	struct thread *thread;
+
+	for (thread = run_queue_head; thread != 0; thread = thread->next) {
+		if (thread->state == THREAD_SLEEPING &&
+			thread->wake_tick <= tick) {
+			thread->wake_tick = 0;
+			thread->state = THREAD_READY;
+		}
+	}
+}
+
 void sched_yield(void)
 {
 	struct thread *prev = current_thread;
 	struct thread *next = next_runnable_thread();
 
+	if (schedule_locked != 0) {
+		return;
+	}
+
 	if (next == 0 || next == prev) {
 		return;
 	}
 
+	schedule_locked = 1;
+
 	if (prev != 0 && prev->state == THREAD_RUNNING) {
 		prev->state = THREAD_READY;
 	}
 
 	next->state = THREAD_RUNNING;
 	current_thread = next;
+	schedule_locked = 0;
 
 	if (prev == 0) {
 		arch_context_switch(&boot_stack_pointer, next->stack_pointer);
@@ -162,6 +191,90 @@ void sched_yield(void)
 	arch_context_switch(&prev->stack_pointer, next->stack_pointer);
 }
 
+void sched_tick(uint64_t tick)
+{
+	wake_sleeping_threads(tick);
+
+	if (current_thread != 0 && current_thread->state == THREAD_RUNNING) {
+		sched_yield();
+	}
+}
+
+void sched_sleep(uint64_t ticks)
+{
+	uint64_t now;
+
+	if (current_thread == 0 || ticks == 0) {
+		return;
+	}
+
+	now = timer_ticks();
+	current_thread->wake_tick = now + ticks;
+	current_thread->state = THREAD_SLEEPING;
+	sched_yield();
+}
+
+void wait_queue_init(struct wait_queue *queue)
+{
+	if (queue == 0) {
+		return;
+	}
+
+	queue->head = 0;
+	queue->tail = 0;
+}
+
+static void wait_queue_enqueue(struct wait_queue *queue, struct thread *thread)
+{
+	thread->wait_next = 0;
+
+	if (queue->tail != 0) {
+		queue->tail->wait_next = thread;
+	} else {
+		queue->head = thread;
+	}
+
+	queue->tail = thread;
+}
+
+void wait_queue_sleep(struct wait_queue *queue)
+{
+	if (queue == 0 || current_thread == 0) {
+		return;
+	}
+
+	wait_queue_enqueue(queue, current_thread);
+	current_thread->state = THREAD_WAITING;
+	sched_yield();
+}
+
+void wait_queue_wake_one(struct wait_queue *queue)
+{
+	struct thread *thread;
+
+	if (queue == 0 || queue->head == 0) {
+		return;
+	}
+
+	thread = queue->head;
+	queue->head = thread->wait_next;
+	if (queue->head == 0) {
+		queue->tail = 0;
+	}
+
+	thread->wait_next = 0;
+	if (thread->state == THREAD_WAITING) {
+		thread->state = THREAD_READY;
+	}
+}
+
+void wait_queue_wake_all(struct wait_queue *queue)
+{
+	while (queue != 0 && queue->head != 0) {
+		wait_queue_wake_one(queue);
+	}
+}
+
 static void thread_trampoline(void)
 {
 	struct thread *thread = current_thread;
@@ -218,12 +331,42 @@ static void scheduler_demo_entry(void *arg)
 	uint64_t step;
 
 	for (step = 1; step <= 3; step++) {
-		early_log_puts("thread ");
+		early_log_puts("preempt thread ");
 		early_log_u64_decimal(id);
 		early_log_puts(" step=");
 		early_log_u64_decimal(step);
 		early_log_puts("\n");
-		sched_yield();
+		sched_sleep(2);
+	}
+}
+
+static struct wait_queue demo_wait_queue;
+
+static void wait_queue_demo_waiter(void *arg)
+{
+	(void)arg;
+
+	early_log_puts("waiter sleeping\n");
+	wait_queue_sleep(&demo_wait_queue);
+	early_log_puts("waiter woke\n");
+}
+
+static void wait_queue_demo_waker(void *arg)
+{
+	(void)arg;
+
+	early_log_puts("waker sleeping\n");
+	sched_sleep(4);
+	early_log_puts("waker wake_one\n");
+	wait_queue_wake_one(&demo_wait_queue);
+}
+
+static void idle_thread_entry(void *arg)
+{
+	(void)arg;
+
+	for (;;) {
+		__asm__ volatile("hlt");
 	}
 }
 
@@ -235,6 +378,7 @@ void sched_init(void)
 
 	run_queue_head = 0;
 	run_queue_tail = 0;
+	idle_thread = 0;
 	scheduler_ready = 1;
 
 	early_log_puts("scheduler initialized\n");
@@ -247,11 +391,18 @@ void sched_start(void)
 		"round-robin-a", scheduler_demo_entry, (void *)(uintptr_t)1);
 	struct thread *second = kernel_thread_create(
 		"round-robin-b", scheduler_demo_entry, (void *)(uintptr_t)2);
+	struct thread *waiter =
+		kernel_thread_create("waiter", wait_queue_demo_waiter, 0);
+	struct thread *waker =
+		kernel_thread_create("waker", wait_queue_demo_waker, 0);
+	idle_thread = kernel_thread_create("idle", idle_thread_entry, 0);
 
-	if (first == 0 || second == 0) {
+	if (first == 0 || second == 0 || waiter == 0 || waker == 0 ||
+		idle_thread == 0) {
 		panic("scheduler demo thread creation failed");
 	}
 
+	wait_queue_init(&demo_wait_queue);
 	early_log_puts("scheduler starting\n");
 	sched_yield();
 

kernel/time/timer.c

@@ -1,6 +1,7 @@
 #include <stdint.h>
 
 #include <tianole/early_log.h>
+#include <tianole/sched.h>
 #include <tianole/timer.h>
 
 static uint64_t tick_count;
@@ -14,6 +15,8 @@ void timer_tick(void)
 		early_log_u64_decimal(tick_count);
 		early_log_puts("\n");
 	}
+
+	sched_tick(tick_count);
 }
 
 uint64_t timer_ticks(void)

scripts/checks/boot.sh

@@ -27,12 +27,16 @@ check_lines build/debug.log \
 	"kernel thread selftest ok" \
 	"timer initialized" \
 	"scheduler starting" \
-	"thread 1 step=1" \
-	"thread 2 step=1" \
-	"thread 1 step=2" \
-	"thread 2 step=2" \
-	"thread 1 step=3" \
-	"thread 2 step=3" \
+	"preempt thread 1 step=1" \
+	"preempt thread 2 step=1" \
+	"waiter sleeping" \
+	"waker sleeping" \
+	"preempt thread 1 step=2" \
+	"preempt thread 2 step=2" \
+	"preempt thread 1 step=3" \
+	"preempt thread 2 step=3" \
+	"waker wake_one" \
+	"waiter woke" \
 	"timer tick=1" \
 	"timer tick=2" \
 	"timer tick=3"
@@ -54,12 +58,16 @@ check_lines build/serial.log \
 	"kernel thread selftest ok" \
 	"timer initialized" \
 	"scheduler starting" \
-	"thread 1 step=1" \
-	"thread 2 step=1" \
-	"thread 1 step=2" \
-	"thread 2 step=2" \
-	"thread 1 step=3" \
-	"thread 2 step=3" \
+	"preempt thread 1 step=1" \
+	"preempt thread 2 step=1" \
+	"waiter sleeping" \
+	"waker sleeping" \
+	"preempt thread 1 step=2" \
+	"preempt thread 2 step=2" \
+	"preempt thread 1 step=3" \
+	"preempt thread 2 step=3" \
+	"waker wake_one" \
+	"waiter woke" \
 	"timer tick=1" \
 	"timer tick=2" \
 	"timer tick=3"