jcs.org
Serenity Operating System
1/*
2 * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions are met:
7 *
8 * 1. Redistributions of source code must retain the above copyright notice, this
9 * list of conditions and the following disclaimer.
10 *
11 * 2. Redistributions in binary form must reproduce the above copyright notice,
12 * this list of conditions and the following disclaimer in the documentation
13 * and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
16 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
18 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
21 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
22 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
23 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
24 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25 */
26
27#pragma once
28
29#include <AK/Assertions.h>
30#include <AK/Atomic.h>
31#include <AK/Types.h>
32#include <Kernel/Arch/i386/CPU.h>
33#include <Kernel/Forward.h>
34#include <Kernel/WaitQueue.h>
35
36namespace Kernel {
37
38class Lock {
39public:
40 Lock(const char* name = nullptr)
41 : m_name(name)
42 {
43 }
44 ~Lock() {}
45
46 void lock();
47 void unlock();
48 bool force_unlock_if_locked();
49 bool is_locked() const { return m_holder; }
50 void clear_waiters();
51
52 const char* name() const { return m_name; }
53
54private:
55 Atomic<bool> m_lock { false };
56 u32 m_level { 0 };
57 Thread* m_holder { nullptr };
58 const char* m_name { nullptr };
59 WaitQueue m_queue;
60};
61
62class Locker {
63public:
64 [[gnu::always_inline]] inline explicit Locker(Lock& l)
65 : m_lock(l)
66 {
67 lock();
68 }
69 [[gnu::always_inline]] inline ~Locker() { unlock(); }
70 [[gnu::always_inline]] inline void unlock() { m_lock.unlock(); }
71 [[gnu::always_inline]] inline void lock() { m_lock.lock(); }
72
73private:
74 Lock& m_lock;
75};
76
77#define LOCKER(lock) Locker locker(lock)
78
79template<typename T>
80class Lockable {
81public:
82 Lockable() {}
83 Lockable(T&& resource)
84 : m_resource(move(resource))
85 {
86 }
87 Lock& lock() { return m_lock; }
88 T& resource() { return m_resource; }
89
90 T lock_and_copy()
91 {
92 LOCKER(m_lock);
93 return m_resource;
94 }
95
96private:
97 T m_resource;
98 Lock m_lock;
99};
100
101}