Kernel: Add LockFreeGuard to LockGuard.h

kernel/include/kernel/LockGuard.h

@@ -2,6 +2,8 @@
 
 #include <BAN/NoCopyMove.h>
 
+#include <stdint.h>
+
 namespace Kernel
 {
 
@@ -27,4 +29,30 @@ namespace Kernel
 		Lock& m_lock;
 	};
 
+	template<typename Lock>
+	class LockFreeGuard
+	{
+		BAN_NON_COPYABLE(LockFreeGuard);
+		BAN_NON_MOVABLE(LockFreeGuard);
+
+	public:
+		LockFreeGuard(Lock& lock)
+			: m_lock(lock)
+			, m_depth(lock.lock_depth())
+		{
+			for (uint32_t i = 0; i < m_depth; i++)
+				m_lock.unlock();
+		}
+
+		~LockFreeGuard()
+		{
+			for (uint32_t i = 0; i < m_depth; i++)
+				m_lock.lock();
+		}
+
+	private:
+		Lock& m_lock;
+		const uint32_t m_depth;
+	};
+
 }

kernel/include/kernel/SpinLock.h

@@ -19,6 +19,8 @@ namespace Kernel
 		void unlock();
 		bool is_locked() const;
 
+		uint32_t lock_depth() const { return m_locker != -1; }
+
 	private:
 		BAN::Atomic<pid_t> m_locker = -1;
 	};
@@ -34,6 +36,8 @@ namespace Kernel
 		void unlock();
 		bool is_locked() const;
 
+		uint32_t lock_depth() const { return m_lock_depth; }
+
 	private:
 		BAN::Atomic<pid_t>		m_locker		= -1;
 		BAN::Atomic<uint32_t>	m_lock_depth	= 0;