2 * RT Mutexes: blocking mutual exclusion locks with PI support
4 * started by Ingo Molnar and Thomas Gleixner:
6 * Copyright (C) 2004-2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
7 * Copyright (C) 2006, Timesys Corp., Thomas Gleixner <tglx@timesys.com>
9 * This file contains the private data structure and API definitions.
12 #ifndef __KERNEL_RTMUTEX_COMMON_H
13 #define __KERNEL_RTMUTEX_COMMON_H
15 #include <linux/rtmutex.h>
16 #include <linux/sched/wake_q.h>
19 * This is the control structure for tasks blocked on a rt_mutex,
20 * which is allocated on the kernel stack on of the blocked task.
22 * @tree_entry: pi node to enqueue into the mutex waiters tree
23 * @pi_tree_entry: pi node to enqueue into the mutex owner waiters tree
24 * @task: task reference to the blocked task
26 struct rt_mutex_waiter {
27 struct rb_node tree_entry;
28 struct rb_node pi_tree_entry;
29 struct task_struct *task;
30 struct rt_mutex *lock;
31 #ifdef CONFIG_DEBUG_RT_MUTEXES
33 struct pid *deadlock_task_pid;
34 struct rt_mutex *deadlock_lock;
41 * Various helpers to access the waiters-tree:
44 #ifdef CONFIG_RT_MUTEXES
46 static inline int rt_mutex_has_waiters(struct rt_mutex *lock)
48 return !RB_EMPTY_ROOT(&lock->waiters.rb_root);
51 static inline struct rt_mutex_waiter *
52 rt_mutex_top_waiter(struct rt_mutex *lock)
54 struct rt_mutex_waiter *w;
56 w = rb_entry(lock->waiters.rb_leftmost,
57 struct rt_mutex_waiter, tree_entry);
58 BUG_ON(w->lock != lock);
63 static inline int task_has_pi_waiters(struct task_struct *p)
65 return !RB_EMPTY_ROOT(&p->pi_waiters.rb_root);
68 static inline struct rt_mutex_waiter *
69 task_top_pi_waiter(struct task_struct *p)
71 return rb_entry(p->pi_waiters.rb_leftmost,
72 struct rt_mutex_waiter, pi_tree_entry);
77 static inline int rt_mutex_has_waiters(struct rt_mutex *lock)
82 static inline struct rt_mutex_waiter *
83 rt_mutex_top_waiter(struct rt_mutex *lock)
88 static inline int task_has_pi_waiters(struct task_struct *p)
93 static inline struct rt_mutex_waiter *
94 task_top_pi_waiter(struct task_struct *p)
102 * lock->owner state tracking:
104 #define RT_MUTEX_HAS_WAITERS 1UL
106 static inline struct task_struct *rt_mutex_owner(struct rt_mutex *lock)
108 unsigned long owner = (unsigned long) READ_ONCE(lock->owner);
110 return (struct task_struct *) (owner & ~RT_MUTEX_HAS_WAITERS);
114 * Constants for rt mutex functions which have a selectable deadlock
117 * RT_MUTEX_MIN_CHAINWALK: Stops the lock chain walk when there are
118 * no further PI adjustments to be made.
120 * RT_MUTEX_FULL_CHAINWALK: Invoke deadlock detection with a full
121 * walk of the lock chain.
123 enum rtmutex_chainwalk {
124 RT_MUTEX_MIN_CHAINWALK,
125 RT_MUTEX_FULL_CHAINWALK,
129 * PI-futex support (proxy locking functions, etc.):
131 extern struct task_struct *rt_mutex_next_owner(struct rt_mutex *lock);
132 extern void rt_mutex_init_proxy_locked(struct rt_mutex *lock,
133 struct task_struct *proxy_owner);
134 extern void rt_mutex_proxy_unlock(struct rt_mutex *lock,
135 struct task_struct *proxy_owner);
136 extern void rt_mutex_init_waiter(struct rt_mutex_waiter *waiter);
137 extern int __rt_mutex_start_proxy_lock(struct rt_mutex *lock,
138 struct rt_mutex_waiter *waiter,
139 struct task_struct *task);
140 extern int rt_mutex_start_proxy_lock(struct rt_mutex *lock,
141 struct rt_mutex_waiter *waiter,
142 struct task_struct *task);
143 extern int rt_mutex_wait_proxy_lock(struct rt_mutex *lock,
144 struct hrtimer_sleeper *to,
145 struct rt_mutex_waiter *waiter);
146 extern bool rt_mutex_cleanup_proxy_lock(struct rt_mutex *lock,
147 struct rt_mutex_waiter *waiter);
149 extern int rt_mutex_futex_trylock(struct rt_mutex *l);
151 extern void rt_mutex_futex_unlock(struct rt_mutex *lock);
152 extern bool __rt_mutex_futex_unlock(struct rt_mutex *lock,
153 struct wake_q_head *wqh);
155 extern void rt_mutex_postunlock(struct wake_q_head *wake_q);
157 #ifdef CONFIG_DEBUG_RT_MUTEXES
158 # include "rtmutex-debug.h"
160 # include "rtmutex.h"