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 * Constants for rt mutex functions which have a selectable deadlock
106 * detection.
107 *
108 * RT_MUTEX_MIN_CHAINWALK:	Stops the lock chain walk when there are
109 *				no further PI adjustments to be made.
110 *
111 * RT_MUTEX_FULL_CHAINWALK:	Invoke deadlock detection with a full
112 *				walk of the lock chain.
113 */
114enum rtmutex_chainwalk {
115	RT_MUTEX_MIN_CHAINWALK,
116	RT_MUTEX_FULL_CHAINWALK,
117};
118
119/*
120 * PI-futex support (proxy locking functions, etc.):
121 */
122extern struct task_struct *rt_mutex_next_owner(struct rt_mutex *lock);
123extern void rt_mutex_init_proxy_locked(struct rt_mutex *lock,
124				       struct task_struct *proxy_owner);
125extern void rt_mutex_proxy_unlock(struct rt_mutex *lock,
126				  struct task_struct *proxy_owner);
127extern int rt_mutex_start_proxy_lock(struct rt_mutex *lock,
128				     struct rt_mutex_waiter *waiter,
129				     struct task_struct *task);
130extern int rt_mutex_finish_proxy_lock(struct rt_mutex *lock,
131				      struct hrtimer_sleeper *to,
132				      struct rt_mutex_waiter *waiter);
133extern int rt_mutex_timed_futex_lock(struct rt_mutex *l, struct hrtimer_sleeper *to);
134
135#ifdef CONFIG_DEBUG_RT_MUTEXES
136# include "rtmutex-debug.h"
137#else
138# include "rtmutex.h"
139#endif
140
141#endif
142