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 * This is the control structure for tasks blocked on a rt_mutex,
19 * which is allocated on the kernel stack on of the blocked task.
20 *
21 * @tree_entry: pi node to enqueue into the mutex waiters tree
22 * @pi_tree_entry: pi node to enqueue into the mutex owner waiters tree
23 * @task: task reference to the blocked task
24 */
25 struct rt_mutex_waiter {
26 struct rb_node tree_entry;
27 struct rb_node pi_tree_entry;
28 struct task_struct *task;
29 struct rt_mutex *lock;
30 #ifdef CONFIG_DEBUG_RT_MUTEXES
31 unsigned long ip;
32 struct pid *deadlock_task_pid;
33 struct rt_mutex *deadlock_lock;
34 #endif
35 int prio;
36 };
37
38 /*
39 * Various helpers to access the waiters-tree:
40 */
rt_mutex_has_waiters(struct rt_mutex * lock)41 static inline int rt_mutex_has_waiters(struct rt_mutex *lock)
42 {
43 return !RB_EMPTY_ROOT(&lock->waiters);
44 }
45
46 static inline struct rt_mutex_waiter *
rt_mutex_top_waiter(struct rt_mutex * lock)47 rt_mutex_top_waiter(struct rt_mutex *lock)
48 {
49 struct rt_mutex_waiter *w;
50
51 w = rb_entry(lock->waiters_leftmost, struct rt_mutex_waiter,
52 tree_entry);
53 BUG_ON(w->lock != lock);
54
55 return w;
56 }
57
task_has_pi_waiters(struct task_struct * p)58 static inline int task_has_pi_waiters(struct task_struct *p)
59 {
60 return !RB_EMPTY_ROOT(&p->pi_waiters);
61 }
62
63 static inline struct rt_mutex_waiter *
task_top_pi_waiter(struct task_struct * p)64 task_top_pi_waiter(struct task_struct *p)
65 {
66 return rb_entry(p->pi_waiters_leftmost, struct rt_mutex_waiter,
67 pi_tree_entry);
68 }
69
70 /*
71 * lock->owner state tracking:
72 */
73 #define RT_MUTEX_HAS_WAITERS 1UL
74 #define RT_MUTEX_OWNER_MASKALL 1UL
75
rt_mutex_owner(struct rt_mutex * lock)76 static inline struct task_struct *rt_mutex_owner(struct rt_mutex *lock)
77 {
78 unsigned long owner = (unsigned long) READ_ONCE(lock->owner);
79
80 return (struct task_struct *) (owner & ~RT_MUTEX_OWNER_MASKALL);
81 }
82
83 /*
84 * Constants for rt mutex functions which have a selectable deadlock
85 * detection.
86 *
87 * RT_MUTEX_MIN_CHAINWALK: Stops the lock chain walk when there are
88 * no further PI adjustments to be made.
89 *
90 * RT_MUTEX_FULL_CHAINWALK: Invoke deadlock detection with a full
91 * walk of the lock chain.
92 */
93 enum rtmutex_chainwalk {
94 RT_MUTEX_MIN_CHAINWALK,
95 RT_MUTEX_FULL_CHAINWALK,
96 };
97
98 /*
99 * PI-futex support (proxy locking functions, etc.):
100 */
101 extern struct task_struct *rt_mutex_next_owner(struct rt_mutex *lock);
102 extern void rt_mutex_init_proxy_locked(struct rt_mutex *lock,
103 struct task_struct *proxy_owner);
104 extern void rt_mutex_proxy_unlock(struct rt_mutex *lock);
105 extern void rt_mutex_init_waiter(struct rt_mutex_waiter *waiter);
106 extern int rt_mutex_start_proxy_lock(struct rt_mutex *lock,
107 struct rt_mutex_waiter *waiter,
108 struct task_struct *task);
109 extern int rt_mutex_wait_proxy_lock(struct rt_mutex *lock,
110 struct hrtimer_sleeper *to,
111 struct rt_mutex_waiter *waiter);
112 extern bool rt_mutex_cleanup_proxy_lock(struct rt_mutex *lock,
113 struct rt_mutex_waiter *waiter);
114 extern int rt_mutex_futex_trylock(struct rt_mutex *l);
115 extern int __rt_mutex_futex_trylock(struct rt_mutex *l);
116
117 extern void rt_mutex_futex_unlock(struct rt_mutex *lock);
118 extern bool __rt_mutex_futex_unlock(struct rt_mutex *lock,
119 struct wake_q_head *wqh);
120
121 extern void rt_mutex_adjust_prio(struct task_struct *task);
122
123 #ifdef CONFIG_DEBUG_RT_MUTEXES
124 # include "rtmutex-debug.h"
125 #else
126 # include "rtmutex.h"
127 #endif
128
129 #endif
130