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
 25extern 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 * @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
 46 */
 47struct 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;
 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	int prio;
 58};
 59
 60/*
 61 * Various helpers to access the waiters-tree:
 62 */
 63static inline int rt_mutex_has_waiters(struct rt_mutex *lock)
 64{
 65	return !RB_EMPTY_ROOT(&lock->waiters);
 66}
 67
 68static inline struct rt_mutex_waiter *
 69rt_mutex_top_waiter(struct rt_mutex *lock)
 70{
 71	struct rt_mutex_waiter *w;
 72
 73	w = rb_entry(lock->waiters_leftmost, struct rt_mutex_waiter,
 74		     tree_entry);
 75	BUG_ON(w->lock != lock);
 76
 77	return w;
 78}
 79
 80static inline int task_has_pi_waiters(struct task_struct *p)
 81{
 82	return !RB_EMPTY_ROOT(&p->pi_waiters);
 83}
 84
 85static inline struct rt_mutex_waiter *
 86task_top_pi_waiter(struct task_struct *p)
 87{
 88	return rb_entry(p->pi_waiters_leftmost, struct rt_mutex_waiter,
 89			pi_tree_entry);
 90}
 91
 92/*
 93 * lock->owner state tracking:
 94 */
 95#define RT_MUTEX_HAS_WAITERS	1UL
 96#define RT_MUTEX_OWNER_MASKALL	1UL
 97
 98static 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/*
105 * PI-futex support (proxy locking functions, etc.):
106 */
107extern struct task_struct *rt_mutex_next_owner(struct rt_mutex *lock);
108extern void rt_mutex_init_proxy_locked(struct rt_mutex *lock,
109				       struct task_struct *proxy_owner);
110extern void rt_mutex_proxy_unlock(struct rt_mutex *lock,
111				  struct task_struct *proxy_owner);
112extern int rt_mutex_start_proxy_lock(struct rt_mutex *lock,
113				     struct rt_mutex_waiter *waiter,
114				     struct task_struct *task,
115				     int detect_deadlock);
116extern int rt_mutex_finish_proxy_lock(struct rt_mutex *lock,
117				      struct hrtimer_sleeper *to,
118				      struct rt_mutex_waiter *waiter,
119				      int detect_deadlock);
120
121#ifdef CONFIG_DEBUG_RT_MUTEXES
122# include "rtmutex-debug.h"
123#else
124# include "rtmutex.h"
125#endif
126
127#endif