Root/kernel/rtmutex_common.h

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 * @list_entry: pi node to enqueue into the mutex waiters list
44 * @pi_list_entry: pi node to enqueue into the mutex owner waiters list
45 * @task: task reference to the blocked task
46 */
47struct rt_mutex_waiter {
48    struct plist_node list_entry;
49    struct plist_node pi_list_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};
58
59/*
60 * Various helpers to access the waiters-plist:
61 */
62static inline int rt_mutex_has_waiters(struct rt_mutex *lock)
63{
64    return !plist_head_empty(&lock->wait_list);
65}
66
67static inline struct rt_mutex_waiter *
68rt_mutex_top_waiter(struct rt_mutex *lock)
69{
70    struct rt_mutex_waiter *w;
71
72    w = plist_first_entry(&lock->wait_list, struct rt_mutex_waiter,
73                   list_entry);
74    BUG_ON(w->lock != lock);
75
76    return w;
77}
78
79static inline int task_has_pi_waiters(struct task_struct *p)
80{
81    return !plist_head_empty(&p->pi_waiters);
82}
83
84static inline struct rt_mutex_waiter *
85task_top_pi_waiter(struct task_struct *p)
86{
87    return plist_first_entry(&p->pi_waiters, struct rt_mutex_waiter,
88                  pi_list_entry);
89}
90
91/*
92 * lock->owner state tracking:
93 */
94#define RT_MUTEX_HAS_WAITERS 1UL
95#define RT_MUTEX_OWNER_MASKALL 1UL
96
97static inline struct task_struct *rt_mutex_owner(struct rt_mutex *lock)
98{
99    return (struct task_struct *)
100        ((unsigned long)lock->owner & ~RT_MUTEX_OWNER_MASKALL);
101}
102
103/*
104 * PI-futex support (proxy locking functions, etc.):
105 */
106extern struct task_struct *rt_mutex_next_owner(struct rt_mutex *lock);
107extern void rt_mutex_init_proxy_locked(struct rt_mutex *lock,
108                       struct task_struct *proxy_owner);
109extern void rt_mutex_proxy_unlock(struct rt_mutex *lock,
110                  struct task_struct *proxy_owner);
111extern int rt_mutex_start_proxy_lock(struct rt_mutex *lock,
112                     struct rt_mutex_waiter *waiter,
113                     struct task_struct *task,
114                     int detect_deadlock);
115extern int rt_mutex_finish_proxy_lock(struct rt_mutex *lock,
116                      struct hrtimer_sleeper *to,
117                      struct rt_mutex_waiter *waiter,
118                      int detect_deadlock);
119
120#ifdef CONFIG_DEBUG_RT_MUTEXES
121# include "rtmutex-debug.h"
122#else
123# include "rtmutex.h"
124#endif
125
126#endif
127

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