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1/*
2 * RT Mutexes: blocking mutual exclusion locks with PI support
3 *
4 * started by Ingo Molnar and Thomas Gleixner:
5 *
6 * Copyright (C) 2004-2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
7 * Copyright (C) 2006, Timesys Corp., Thomas Gleixner <tglx@timesys.com>
8 *
9 * This file contains the private data structure and API definitions.
10 */
11
12#ifndef __KERNEL_RTMUTEX_COMMON_H
13#define __KERNEL_RTMUTEX_COMMON_H
14
15#include <linux/rtmutex.h>
16
17/*
18 * The rtmutex in kernel tester is independent of rtmutex debugging. We
19 * call schedule_rt_mutex_test() instead of schedule() for the tasks which
20 * belong to the tester. That way we can delay the wakeup path of those
21 * threads to provoke lock stealing and testing of complex boosting scenarios.
22 */
23#ifdef CONFIG_RT_MUTEX_TESTER
24
25extern void schedule_rt_mutex_test(struct rt_mutex *lock);
26
27#define schedule_rt_mutex(_lock) \
28 do { \
29 if (!(current->flags & PF_MUTEX_TESTER)) \
30 schedule(); \
31 else \
32 schedule_rt_mutex_test(_lock); \
33 } while (0)
34
35#else
36# define schedule_rt_mutex(_lock) schedule()
37#endif
38
39/*
40 * This is the control structure for tasks blocked on a rt_mutex,
41 * which is allocated on the kernel stack on of the blocked task.
42 *
43 * @tree_entry: pi node to enqueue into the mutex waiters tree
44 * @pi_tree_entry: pi node to enqueue into the mutex owner waiters tree
45 * @task: task reference to the blocked task
46 */
47struct rt_mutex_waiter {
48 struct rb_node tree_entry;
49 struct rb_node pi_tree_entry;
50 struct task_struct *task;
51 struct rt_mutex *lock;
52#ifdef CONFIG_DEBUG_RT_MUTEXES
53 unsigned long ip;
54 struct pid *deadlock_task_pid;
55 struct rt_mutex *deadlock_lock;
56#endif
57 int prio;
58};
59
60/*
61 * Various helpers to access the waiters-tree:
62 */
63static inline int rt_mutex_has_waiters(struct rt_mutex *lock)
64{
65 return !RB_EMPTY_ROOT(&lock->waiters);
66}
67
68static inline struct rt_mutex_waiter *
69rt_mutex_top_waiter(struct rt_mutex *lock)
70{
71 struct rt_mutex_waiter *w;
72
73 w = rb_entry(lock->waiters_leftmost, struct rt_mutex_waiter,
74 tree_entry);
75 BUG_ON(w->lock != lock);
76
77 return w;
78}
79
80static inline int task_has_pi_waiters(struct task_struct *p)
81{
82 return !RB_EMPTY_ROOT(&p->pi_waiters);
83}
84
85static inline struct rt_mutex_waiter *
86task_top_pi_waiter(struct task_struct *p)
87{
88 return rb_entry(p->pi_waiters_leftmost, struct rt_mutex_waiter,
89 pi_tree_entry);
90}
91
92/*
93 * lock->owner state tracking:
94 */
95#define RT_MUTEX_HAS_WAITERS 1UL
96#define RT_MUTEX_OWNER_MASKALL 1UL
97
98static inline struct task_struct *rt_mutex_owner(struct rt_mutex *lock)
99{
100 return (struct task_struct *)
101 ((unsigned long)lock->owner & ~RT_MUTEX_OWNER_MASKALL);
102}
103
104/*
105 * PI-futex support (proxy locking functions, etc.):
106 */
107extern struct task_struct *rt_mutex_next_owner(struct rt_mutex *lock);
108extern void rt_mutex_init_proxy_locked(struct rt_mutex *lock,
109 struct task_struct *proxy_owner);
110extern void rt_mutex_proxy_unlock(struct rt_mutex *lock,
111 struct task_struct *proxy_owner);
112extern int rt_mutex_start_proxy_lock(struct rt_mutex *lock,
113 struct rt_mutex_waiter *waiter,
114 struct task_struct *task,
115 int detect_deadlock);
116extern int rt_mutex_finish_proxy_lock(struct rt_mutex *lock,
117 struct hrtimer_sleeper *to,
118 struct rt_mutex_waiter *waiter,
119 int detect_deadlock);
120
121#ifdef CONFIG_DEBUG_RT_MUTEXES
122# include "rtmutex-debug.h"
123#else
124# include "rtmutex.h"
125#endif
126
127#endif
1/* SPDX-License-Identifier: GPL-2.0 */
2/*
3 * RT Mutexes: blocking mutual exclusion locks with PI support
4 *
5 * started by Ingo Molnar and Thomas Gleixner:
6 *
7 * Copyright (C) 2004-2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
8 * Copyright (C) 2006, Timesys Corp., Thomas Gleixner <tglx@timesys.com>
9 *
10 * This file contains the private data structure and API definitions.
11 */
12
13#ifndef __KERNEL_RTMUTEX_COMMON_H
14#define __KERNEL_RTMUTEX_COMMON_H
15
16#include <linux/debug_locks.h>
17#include <linux/rtmutex.h>
18#include <linux/sched/wake_q.h>
19
20/*
21 * This is the control structure for tasks blocked on a rt_mutex,
22 * which is allocated on the kernel stack on of the blocked task.
23 *
24 * @tree_entry: pi node to enqueue into the mutex waiters tree
25 * @pi_tree_entry: pi node to enqueue into the mutex owner waiters tree
26 * @task: task reference to the blocked task
27 * @lock: Pointer to the rt_mutex on which the waiter blocks
28 * @prio: Priority of the waiter
29 * @deadline: Deadline of the waiter if applicable
30 */
31struct rt_mutex_waiter {
32 struct rb_node tree_entry;
33 struct rb_node pi_tree_entry;
34 struct task_struct *task;
35 struct rt_mutex *lock;
36 int prio;
37 u64 deadline;
38};
39
40/*
41 * Must be guarded because this header is included from rcu/tree_plugin.h
42 * unconditionally.
43 */
44#ifdef CONFIG_RT_MUTEXES
45static inline int rt_mutex_has_waiters(struct rt_mutex *lock)
46{
47 return !RB_EMPTY_ROOT(&lock->waiters.rb_root);
48}
49
50static inline struct rt_mutex_waiter *rt_mutex_top_waiter(struct rt_mutex *lock)
51{
52 struct rb_node *leftmost = rb_first_cached(&lock->waiters);
53 struct rt_mutex_waiter *w = NULL;
54
55 if (leftmost) {
56 w = rb_entry(leftmost, struct rt_mutex_waiter, tree_entry);
57 BUG_ON(w->lock != lock);
58 }
59 return w;
60}
61
62static inline int task_has_pi_waiters(struct task_struct *p)
63{
64 return !RB_EMPTY_ROOT(&p->pi_waiters.rb_root);
65}
66
67static inline struct rt_mutex_waiter *task_top_pi_waiter(struct task_struct *p)
68{
69 return rb_entry(p->pi_waiters.rb_leftmost, struct rt_mutex_waiter,
70 pi_tree_entry);
71}
72
73#define RT_MUTEX_HAS_WAITERS 1UL
74
75static inline struct task_struct *rt_mutex_owner(struct rt_mutex *lock)
76{
77 unsigned long owner = (unsigned long) READ_ONCE(lock->owner);
78
79 return (struct task_struct *) (owner & ~RT_MUTEX_HAS_WAITERS);
80}
81#else /* CONFIG_RT_MUTEXES */
82/* Used in rcu/tree_plugin.h */
83static inline struct task_struct *rt_mutex_owner(struct rt_mutex *lock)
84{
85 return NULL;
86}
87#endif /* !CONFIG_RT_MUTEXES */
88
89/*
90 * Constants for rt mutex functions which have a selectable deadlock
91 * detection.
92 *
93 * RT_MUTEX_MIN_CHAINWALK: Stops the lock chain walk when there are
94 * no further PI adjustments to be made.
95 *
96 * RT_MUTEX_FULL_CHAINWALK: Invoke deadlock detection with a full
97 * walk of the lock chain.
98 */
99enum rtmutex_chainwalk {
100 RT_MUTEX_MIN_CHAINWALK,
101 RT_MUTEX_FULL_CHAINWALK,
102};
103
104static inline void __rt_mutex_basic_init(struct rt_mutex *lock)
105{
106 lock->owner = NULL;
107 raw_spin_lock_init(&lock->wait_lock);
108 lock->waiters = RB_ROOT_CACHED;
109}
110
111/*
112 * PI-futex support (proxy locking functions, etc.):
113 */
114extern void rt_mutex_init_proxy_locked(struct rt_mutex *lock,
115 struct task_struct *proxy_owner);
116extern void rt_mutex_proxy_unlock(struct rt_mutex *lock);
117extern void rt_mutex_init_waiter(struct rt_mutex_waiter *waiter);
118extern int __rt_mutex_start_proxy_lock(struct rt_mutex *lock,
119 struct rt_mutex_waiter *waiter,
120 struct task_struct *task);
121extern int rt_mutex_start_proxy_lock(struct rt_mutex *lock,
122 struct rt_mutex_waiter *waiter,
123 struct task_struct *task);
124extern int rt_mutex_wait_proxy_lock(struct rt_mutex *lock,
125 struct hrtimer_sleeper *to,
126 struct rt_mutex_waiter *waiter);
127extern bool rt_mutex_cleanup_proxy_lock(struct rt_mutex *lock,
128 struct rt_mutex_waiter *waiter);
129
130extern int rt_mutex_futex_trylock(struct rt_mutex *l);
131extern int __rt_mutex_futex_trylock(struct rt_mutex *l);
132
133extern void rt_mutex_futex_unlock(struct rt_mutex *lock);
134extern bool __rt_mutex_futex_unlock(struct rt_mutex *lock,
135 struct wake_q_head *wqh);
136
137extern void rt_mutex_postunlock(struct wake_q_head *wake_q);
138
139/* Debug functions */
140static inline void debug_rt_mutex_unlock(struct rt_mutex *lock)
141{
142 if (IS_ENABLED(CONFIG_DEBUG_RT_MUTEXES))
143 DEBUG_LOCKS_WARN_ON(rt_mutex_owner(lock) != current);
144}
145
146static inline void debug_rt_mutex_proxy_unlock(struct rt_mutex *lock)
147{
148 if (IS_ENABLED(CONFIG_DEBUG_RT_MUTEXES))
149 DEBUG_LOCKS_WARN_ON(!rt_mutex_owner(lock));
150}
151
152static inline void debug_rt_mutex_init_waiter(struct rt_mutex_waiter *waiter)
153{
154 if (IS_ENABLED(CONFIG_DEBUG_RT_MUTEXES))
155 memset(waiter, 0x11, sizeof(*waiter));
156}
157
158static inline void debug_rt_mutex_free_waiter(struct rt_mutex_waiter *waiter)
159{
160 if (IS_ENABLED(CONFIG_DEBUG_RT_MUTEXES))
161 memset(waiter, 0x22, sizeof(*waiter));
162}
163
164#endif