summaryrefslogtreecommitdiffstats
path: root/kernel/locking/rtmutex_common.h
blob: 7844f8f0e6391ec3df8c3532e5fe17f1b8fd4a5a (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
/*
 * RT Mutexes: blocking mutual exclusion locks with PI support
 *
 * started by Ingo Molnar and Thomas Gleixner:
 *
 *  Copyright (C) 2004-2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
 *  Copyright (C) 2006, Timesys Corp., Thomas Gleixner <tglx@timesys.com>
 *
 * This file contains the private data structure and API definitions.
 */

#ifndef __KERNEL_RTMUTEX_COMMON_H
#define __KERNEL_RTMUTEX_COMMON_H

#include <linux/rtmutex.h>

/*
 * The rtmutex in kernel tester is independent of rtmutex debugging. We
 * call schedule_rt_mutex_test() instead of schedule() for the tasks which
 * belong to the tester. That way we can delay the wakeup path of those
 * threads to provoke lock stealing and testing of  complex boosting scenarios.
 */
#ifdef CONFIG_RT_MUTEX_TESTER

extern void schedule_rt_mutex_test(struct rt_mutex *lock);

#define schedule_rt_mutex(_lock)				\
  do {								\
	if (!(current->flags & PF_MUTEX_TESTER))		\
		schedule();					\
	else							\
		schedule_rt_mutex_test(_lock);			\
  } while (0)

#else
# define schedule_rt_mutex(_lock)			schedule()
#endif

/*
 * This is the control structure for tasks blocked on a rt_mutex,
 * which is allocated on the kernel stack on of the blocked task.
 *
 * @tree_entry:		pi node to enqueue into the mutex waiters tree
 * @pi_tree_entry:	pi node to enqueue into the mutex owner waiters tree
 * @task:		task reference to the blocked task
 */
struct rt_mutex_waiter {
	struct rb_node          tree_entry;
	struct rb_node          pi_tree_entry;
	struct task_struct	*task;
	struct rt_mutex		*lock;
#ifdef CONFIG_DEBUG_RT_MUTEXES
	unsigned long		ip;
	struct pid		*deadlock_task_pid;
	struct rt_mutex		*deadlock_lock;
#endif
	int prio;
};

/*
 * Various helpers to access the waiters-tree:
 */
static inline int rt_mutex_has_waiters(struct rt_mutex *lock)
{
	return !RB_EMPTY_ROOT(&lock->waiters);
}

static inline struct rt_mutex_waiter *
rt_mutex_top_waiter(struct rt_mutex *lock)
{
	struct rt_mutex_waiter *w;

	w = rb_entry(lock->waiters_leftmost, struct rt_mutex_waiter,
		     tree_entry);
	BUG_ON(w->lock != lock);

	return w;
}

static inline int task_has_pi_waiters(struct task_struct *p)
{
	return !RB_EMPTY_ROOT(&p->pi_waiters);
}

static inline struct rt_mutex_waiter *
task_top_pi_waiter(struct task_struct *p)
{
	return rb_entry(p->pi_waiters_leftmost, struct rt_mutex_waiter,
			pi_tree_entry);
}

/*
 * lock->owner state tracking:
 */
#define RT_MUTEX_HAS_WAITERS	1UL
#define RT_MUTEX_OWNER_MASKALL	1UL

static inline struct task_struct *rt_mutex_owner(struct rt_mutex *lock)
{
	return (struct task_struct *)
		((unsigned long)lock->owner & ~RT_MUTEX_OWNER_MASKALL);
}

/*
 * Constants for rt mutex functions which have a selectable deadlock
 * detection.
 *
 * RT_MUTEX_MIN_CHAINWALK:	Stops the lock chain walk when there are
 *				no further PI adjustments to be made.
 *
 * RT_MUTEX_FULL_CHAINWALK:	Invoke deadlock detection with a full
 *				walk of the lock chain.
 */
enum rtmutex_chainwalk {
	RT_MUTEX_MIN_CHAINWALK,
	RT_MUTEX_FULL_CHAINWALK,
};

/*
 * PI-futex support (proxy locking functions, etc.):
 */
extern struct task_struct *rt_mutex_next_owner(struct rt_mutex *lock);
extern void rt_mutex_init_proxy_locked(struct rt_mutex *lock,
				       struct task_struct *proxy_owner);
extern void rt_mutex_proxy_unlock(struct rt_mutex *lock,
				  struct task_struct *proxy_owner);
extern int rt_mutex_start_proxy_lock(struct rt_mutex *lock,
				     struct rt_mutex_waiter *waiter,
				     struct task_struct *task);
extern int rt_mutex_finish_proxy_lock(struct rt_mutex *lock,
				      struct hrtimer_sleeper *to,
				      struct rt_mutex_waiter *waiter);
extern int rt_mutex_timed_futex_lock(struct rt_mutex *l, struct hrtimer_sleeper *to);
extern bool rt_mutex_futex_unlock(struct rt_mutex *lock,
				  struct wake_q_head *wqh);
extern void rt_mutex_adjust_prio(struct task_struct *task);

#ifdef CONFIG_DEBUG_RT_MUTEXES
# include "rtmutex-debug.h"
#else
# include "rtmutex.h"
#endif

#endif