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>
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.
23 #ifdef CONFIG_RT_MUTEX_TESTER
25 extern void schedule_rt_mutex_test(struct rt_mutex *lock);
27 #define schedule_rt_mutex(_lock) \
29 if (!(current->flags & PF_MUTEX_TESTER)) \
32 schedule_rt_mutex_test(_lock); \
36 # define schedule_rt_mutex(_lock) schedule()
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.
43 * @tree_entry: pi node to enqueue into the mutex waiters tree
44 * @pi_tree_entry: pi node to enqueue into the mutex owner waiters tree
45 * @task: task reference to the blocked task
47 struct rt_mutex_waiter {
48 struct rb_node tree_entry;
49 struct rb_node pi_tree_entry;
50 struct task_struct *task;
51 struct rt_mutex *lock;
53 #ifdef CONFIG_DEBUG_RT_MUTEXES
55 struct pid *deadlock_task_pid;
56 struct rt_mutex *deadlock_lock;
62 * Various helpers to access the waiters-tree:
64 static inline int rt_mutex_has_waiters(struct rt_mutex *lock)
66 return !RB_EMPTY_ROOT(&lock->waiters);
69 static inline struct rt_mutex_waiter *
70 rt_mutex_top_waiter(struct rt_mutex *lock)
72 struct rt_mutex_waiter *w;
74 w = rb_entry(lock->waiters_leftmost, struct rt_mutex_waiter,
76 BUG_ON(w->lock != lock);
81 static inline int task_has_pi_waiters(struct task_struct *p)
83 return !RB_EMPTY_ROOT(&p->pi_waiters);
86 static inline struct rt_mutex_waiter *
87 task_top_pi_waiter(struct task_struct *p)
89 return rb_entry(p->pi_waiters_leftmost, struct rt_mutex_waiter,
94 * lock->owner state tracking:
96 #define RT_MUTEX_HAS_WAITERS 1UL
97 #define RT_MUTEX_OWNER_MASKALL 1UL
99 static inline struct task_struct *rt_mutex_owner(struct rt_mutex *lock)
101 return (struct task_struct *)
102 ((unsigned long)lock->owner & ~RT_MUTEX_OWNER_MASKALL);
106 * Constants for rt mutex functions which have a selectable deadlock
109 * RT_MUTEX_MIN_CHAINWALK: Stops the lock chain walk when there are
110 * no further PI adjustments to be made.
112 * RT_MUTEX_FULL_CHAINWALK: Invoke deadlock detection with a full
113 * walk of the lock chain.
115 enum rtmutex_chainwalk {
116 RT_MUTEX_MIN_CHAINWALK,
117 RT_MUTEX_FULL_CHAINWALK,
121 * PI-futex support (proxy locking functions, etc.):
123 #define PI_WAKEUP_INPROGRESS ((struct rt_mutex_waiter *) 1)
124 #define PI_REQUEUE_INPROGRESS ((struct rt_mutex_waiter *) 2)
126 extern struct task_struct *rt_mutex_next_owner(struct rt_mutex *lock);
127 extern void rt_mutex_init_proxy_locked(struct rt_mutex *lock,
128 struct task_struct *proxy_owner);
129 extern void rt_mutex_proxy_unlock(struct rt_mutex *lock,
130 struct task_struct *proxy_owner);
131 extern int rt_mutex_start_proxy_lock(struct rt_mutex *lock,
132 struct rt_mutex_waiter *waiter,
133 struct task_struct *task);
134 extern int rt_mutex_finish_proxy_lock(struct rt_mutex *lock,
135 struct hrtimer_sleeper *to,
136 struct rt_mutex_waiter *waiter);
137 extern int rt_mutex_timed_futex_lock(struct rt_mutex *l, struct hrtimer_sleeper *to);
139 extern bool rt_mutex_futex_unlock(struct rt_mutex *lock);
141 extern void rt_mutex_adjust_prio(struct task_struct *task);
143 #ifdef CONFIG_DEBUG_RT_MUTEXES
144 # include "rtmutex-debug.h"
146 # include "rtmutex.h"
150 rt_mutex_init_waiter(struct rt_mutex_waiter *waiter, bool savestate)
152 debug_rt_mutex_init_waiter(waiter);
154 waiter->savestate = savestate;
155 RB_CLEAR_NODE(&waiter->pi_tree_entry);
156 RB_CLEAR_NODE(&waiter->tree_entry);