new: mutex

kernel/common/mutex.c

@@ -0,0 +1,120 @@
+#include <common/mutex.h>
+#include <mm/slab.h>
+#include <sched/sched.h>
+
+/**
+ * @brief 初始化互斥量
+ *
+ * @param lock mutex结构体
+ */
+void mutex_init(mutex_t *lock)
+{
+    atomic_set(&lock->count, 1);
+    spin_init(&lock->wait_lock);
+    list_init(&lock->wait_list);
+}
+
+static void __mutex_sleep()
+{
+    current_pcb->state = PROC_UNINTERRUPTIBLE;
+    sched_cfs();
+}
+
+static void __mutex_acquire(mutex_t *lock)
+{
+}
+/**
+ * @brief 对互斥量加锁
+ *
+ * @param lock mutex结构体
+ */
+void mutex_lock(mutex_t *lock)
+{
+    bool lock_ok = 0;
+
+    while (lock_ok == false)
+    {
+        spin_lock(&lock->wait_lock);
+        if (likely(mutex_is_locked(lock)))
+        {
+            struct mutex_waiter_t *waiter = (struct mutex_waiter_t *)kmalloc(sizeof(struct mutex_waiter_t), 0);
+            if (waiter == NULL)
+            {
+                kerror("In mutex_lock: no memory to alloc waiter. Program's behaviour might be indetermined!");
+                spin_unlock(&lock->wait_lock);
+                return;
+            }
+            memset(waiter, 0, sizeof(struct mutex_waiter_t));
+            waiter->pcb = current_pcb;
+            list_init(&waiter->list);
+            list_append(&lock->wait_list, &waiter->list);
+
+            spin_unlock(&lock->wait_lock);
+
+            __mutex_sleep();
+        }
+        else
+        {
+            atomic_dec(&lock->count);
+            spin_unlock(&lock->wait_lock);
+            lock_ok = true;
+        }
+    }
+}
+
+/**
+ * @brief 对互斥量解锁
+ *
+ * @param lock mutex结构体
+ */
+void mutex_unlock(mutex_t *lock)
+{
+    if (unlikely(!mutex_is_locked(lock)))
+        return;
+    
+    spin_lock(&lock->wait_lock);
+    struct mutex_waiter_t *wt = NULL;
+    if (mutex_is_locked(lock))
+    {
+        if (!list_empty(&lock->wait_list))
+            wt = container_of(list_next(&lock->wait_list), struct mutex_waiter_t, list);
+
+        atomic_inc(&lock->count);
+        if (wt != NULL)
+            list_del(&wt->list);
+    }
+
+    spin_unlock(&lock->wait_lock);
+
+    if (wt != NULL)
+    {
+        process_wakeup(wt->pcb);
+        kfree(wt);
+    }
+}
+
+/**
+ * @brief 尝试对互斥量加锁
+ *
+ * @param lock mutex结构体
+ *
+ * @return 成功加锁->1, 加锁失败->0
+ */
+int mutex_trylock(mutex_t *lock)
+{
+    if (mutex_is_locked(lock))
+        return 0;
+
+    spin_lock(&lock->wait_lock);
+    if (mutex_is_locked(lock))
+    {
+        spin_unlock(&lock->wait_lock);
+        return 0;
+    }
+    else
+    {
+        atomic_dec(&lock->count);
+        spin_unlock(&lock->wait_lock);
+        return 1;
+    }
+}