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 u64 deadline;
37 };
38
39 /*
40 * Various helpers to access the waiters-tree:
41 */
rt_mutex_has_waiters(struct rt_mutex * lock)42 static inline int rt_mutex_has_waiters(struct rt_mutex *lock)
43 {
44 return !RB_EMPTY_ROOT(&lock->waiters);
45 }
46
47 static inline struct rt_mutex_waiter *
rt_mutex_top_waiter(struct rt_mutex * lock)48 rt_mutex_top_waiter(struct rt_mutex *lock)
49 {
50 struct rt_mutex_waiter *w;
51
52 w = rb_entry(lock->waiters_leftmost, struct rt_mutex_waiter,
53 tree_entry);
54 BUG_ON(w->lock != lock);
55
56 return w;
57 }
58
task_has_pi_waiters(struct task_struct * p)59 static inline int task_has_pi_waiters(struct task_struct *p)
60 {
61 return !RB_EMPTY_ROOT(&p->pi_waiters);
62 }
63
64 static inline struct rt_mutex_waiter *
task_top_pi_waiter(struct task_struct * p)65 task_top_pi_waiter(struct task_struct *p)
66 {
67 return rb_entry(p->pi_waiters_leftmost, struct rt_mutex_waiter,
68 pi_tree_entry);
69 }
70
71 /*
72 * lock->owner state tracking:
73 */
74 #define RT_MUTEX_HAS_WAITERS 1UL
75 #define RT_MUTEX_OWNER_MASKALL 1UL
76
rt_mutex_owner(struct rt_mutex * lock)77 static inline struct task_struct *rt_mutex_owner(struct rt_mutex *lock)
78 {
79 unsigned long owner = (unsigned long) READ_ONCE(lock->owner);
80
81 return (struct task_struct *) (owner & ~RT_MUTEX_OWNER_MASKALL);
82 }
83
84 /*
85 * Constants for rt mutex functions which have a selectable deadlock
86 * detection.
87 *
88 * RT_MUTEX_MIN_CHAINWALK: Stops the lock chain walk when there are
89 * no further PI adjustments to be made.
90 *
91 * RT_MUTEX_FULL_CHAINWALK: Invoke deadlock detection with a full
92 * walk of the lock chain.
93 */
94 enum rtmutex_chainwalk {
95 RT_MUTEX_MIN_CHAINWALK,
96 RT_MUTEX_FULL_CHAINWALK,
97 };
98
99 /*
100 * PI-futex support (proxy locking functions, etc.):
101 */
102 extern struct task_struct *rt_mutex_next_owner(struct rt_mutex *lock);
103 extern void rt_mutex_init_proxy_locked(struct rt_mutex *lock,
104 struct task_struct *proxy_owner);
105 extern void rt_mutex_proxy_unlock(struct rt_mutex *lock,
106 struct task_struct *proxy_owner);
107 extern int rt_mutex_start_proxy_lock(struct rt_mutex *lock,
108 struct rt_mutex_waiter *waiter,
109 struct task_struct *task);
110 extern int rt_mutex_finish_proxy_lock(struct rt_mutex *lock,
111 struct hrtimer_sleeper *to,
112 struct rt_mutex_waiter *waiter);
113 extern int rt_mutex_timed_futex_lock(struct rt_mutex *l, struct hrtimer_sleeper *to);
114 extern bool rt_mutex_futex_unlock(struct rt_mutex *lock,
115 struct wake_q_head *wqh);
116 extern void rt_mutex_adjust_prio(struct task_struct *task);
117
118 #ifdef CONFIG_DEBUG_RT_MUTEXES
119 # include "rtmutex-debug.h"
120 #else
121 # include "rtmutex.h"
122 #endif
123
124 #endif
125