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
25 extern 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 */
47 struct 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 */
62 static inline int rt_mutex_has_waiters(struct rt_mutex *lock)
63 {
64 return !plist_head_empty(&lock->wait_list);
65 }
66
67 static inline struct rt_mutex_waiter *
68 rt_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
79 static inline int task_has_pi_waiters(struct task_struct *p)
80 {
81 return !plist_head_empty(&p->pi_waiters);
82 }
83
84 static inline struct rt_mutex_waiter *
85 task_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_OWNER_PENDING 1UL
95 #define RT_MUTEX_HAS_WAITERS 2UL
96 #define RT_MUTEX_OWNER_MASKALL 3UL
97
98 static 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 static inline struct task_struct *rt_mutex_real_owner(struct rt_mutex *lock)
105 {
106 return (struct task_struct *)
107 ((unsigned long)lock->owner & ~RT_MUTEX_HAS_WAITERS);
108 }
109
110 static inline unsigned long rt_mutex_owner_pending(struct rt_mutex *lock)
111 {
112 return (unsigned long)lock->owner & RT_MUTEX_OWNER_PENDING;
113 }
114
115 /*
116 * PI-futex support (proxy locking functions, etc.):
117 */
118 extern struct task_struct *rt_mutex_next_owner(struct rt_mutex *lock);
119 extern void rt_mutex_init_proxy_locked(struct rt_mutex *lock,
120 struct task_struct *proxy_owner);
121 extern void rt_mutex_proxy_unlock(struct rt_mutex *lock,
122 struct task_struct *proxy_owner);
123 extern int rt_mutex_start_proxy_lock(struct rt_mutex *lock,
124 struct rt_mutex_waiter *waiter,
125 struct task_struct *task,
126 int detect_deadlock);
127 extern int rt_mutex_finish_proxy_lock(struct rt_mutex *lock,
128 struct hrtimer_sleeper *to,
129 struct rt_mutex_waiter *waiter,
130 int detect_deadlock);
131
132 #ifdef CONFIG_DEBUG_RT_MUTEXES
133 # include "rtmutex-debug.h"
134 #else
135 # include "rtmutex.h"
136 #endif
137
138 #endif
139
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