[kernel][C++] add some simple C++ wrapper and RAII holders for various locks

Just a wrapper around mutex and spinlock for now.

kernel/include/kernel/mutex.h

@@ -52,3 +52,56 @@ static bool is_mutex_held(const mutex_t *m) {
 }
 
 __END_CDECLS
+
+#ifdef __cplusplus
+
+#include <lk/cpp.h>
+
+// C++ wrapper object
+class Mutex {
+public:
+    constexpr Mutex() = default;
+    ~Mutex() { mutex_destroy(&lock_); }
+
+    status_t acquire(lk_time_t timeout) { return mutex_acquire_timeout(&lock_, timeout); }
+    status_t release() { return mutex_release(&lock_); }
+    bool is_held() { return is_mutex_held(&lock_); }
+
+    // suppress default constructors
+    DISALLOW_COPY_ASSIGN_AND_MOVE(Mutex);
+
+private:
+    mutex_t lock_ = MUTEX_INITIAL_VALUE(lock_);
+
+    // AutoLock has access to the inner lock
+    friend class AutoLock;
+};
+
+// RAII wrapper around the mutex
+class AutoLock {
+public:
+    explicit AutoLock(mutex_t *mutex) : mutex_(mutex) { mutex_acquire(mutex_); }
+    AutoLock(mutex_t &mutex) : AutoLock(&mutex) {}
+
+    explicit AutoLock(Mutex *mutex) : AutoLock(&mutex->lock_) {}
+    AutoLock(Mutex &mutex) : AutoLock(&mutex) {}
+
+    ~AutoLock() { release(); }
+
+    // early release the mutex before the object goes out of scope
+    void release() {
+        if (likely(mutex_)) {
+            mutex_release(mutex_);
+            mutex_ = nullptr;
+        }
+    }
+
+    // suppress default constructors
+    DISALLOW_COPY_ASSIGN_AND_MOVE(AutoLock);
+
+private:
+    mutex_t *mutex_ = nullptr;
+};
+
+#endif // __cplusplus
+

kernel/include/kernel/spinlock.h

@@ -69,3 +69,82 @@ static inline void spin_unlock_restore(
 #define spin_unlock_irqrestore(lock, statep) spin_unlock_restore(lock, statep, SPIN_LOCK_FLAG_INTERRUPTS)
 
 __END_CDECLS
+
+#ifdef __cplusplus
+
+#include <lk/cpp.h>
+#include <assert.h>
+
+// C++ wrapper around a C spinlock_t
+class SpinLock {
+public:
+    constexpr SpinLock() = default;
+    ~SpinLock() { DEBUG_ASSERT(!is_held()); }
+
+    void lock() { spin_lock(&lock_); }
+    int trylock() { return spin_trylock(&lock_); }
+    void unlock() { spin_unlock(&lock_); }
+    bool is_held() { return spin_lock_held(&lock_); }
+
+    void lock_irqsave(spin_lock_saved_state_t *state) {
+        spin_lock_save(&lock_, state, SPIN_LOCK_FLAG_INTERRUPTS);
+    }
+
+    void unlock_irqrestore(spin_lock_saved_state_t state) {
+        spin_unlock_restore(&lock_, state, SPIN_LOCK_FLAG_INTERRUPTS);
+    }
+
+    // suppress default constructors
+    DISALLOW_COPY_ASSIGN_AND_MOVE(SpinLock);
+
+private:
+    spin_lock_t lock_ = SPIN_LOCK_INITIAL_VALUE;
+
+    // friend classes to get to the inner lock
+    friend class AutoSpinLock;
+    friend class AutoSpinLockNoIrqSave;
+};
+
+// RAII wrappers for a spinlock, with and without IRQ Save
+class AutoSpinLock {
+public:
+    explicit AutoSpinLock(spin_lock_t *lock) : lock_(lock) { spin_lock_irqsave(lock_, state_); }
+    explicit AutoSpinLock(SpinLock *lock) : AutoSpinLock(&lock->lock_) {}
+    ~AutoSpinLock() { release(); }
+
+    void release() {
+        if (likely(lock_)) {
+            spin_unlock_irqrestore(lock_, state_);
+            lock_ = nullptr;
+        }
+    }
+
+    // suppress default constructors
+    DISALLOW_COPY_ASSIGN_AND_MOVE(AutoSpinLock);
+
+private:
+    spin_lock_t *lock_;
+    spin_lock_saved_state_t state_;
+};
+
+class AutoSpinLockNoIrqSave {
+public:
+    explicit AutoSpinLockNoIrqSave(spin_lock_t *lock) : lock_(lock) { spin_lock(lock_); }
+    explicit AutoSpinLockNoIrqSave(SpinLock *lock) : AutoSpinLockNoIrqSave(&lock->lock_) {}
+    ~AutoSpinLockNoIrqSave() { release(); }
+
+    void release() {
+        if (likely(lock_)) {
+            spin_unlock(lock_);
+            lock_ = nullptr;
+        }
+    }
+
+    // suppress default constructors
+    DISALLOW_COPY_ASSIGN_AND_MOVE(AutoSpinLockNoIrqSave);
+
+private:
+    spin_lock_t *lock_;
+};
+
+#endif // __cplusplus

kernel/include/kernel/wait.h

@@ -7,11 +7,9 @@
  */
 #pragma once
 
-#include <arch/defines.h>
-#include <arch/ops.h>
-#include <arch/thread.h>
 #include <lk/compiler.h>
 #include <lk/list.h>
+#include <stdbool.h>
 #include <sys/types.h>
 
 __BEGIN_CDECLS
@@ -63,6 +61,7 @@ int wait_queue_wake_all(wait_queue_t *, bool reschedule, status_t wait_queue_err
  * remove the thread from whatever wait queue it's in.
  * return an error if the thread is not currently blocked (or is the current thread)
  */
+struct thread;
 status_t thread_unblock_from_wait_queue(struct thread *t, status_t wait_queue_error);
 
 __END_CDECLS