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 */
 25struct 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 */
 41static inline int rt_mutex_has_waiters(struct rt_mutex *lock)
 42{
 43	return !RB_EMPTY_ROOT(&lock->waiters);
 44}
 45
 46static inline struct rt_mutex_waiter *
 47rt_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
 58static inline int task_has_pi_waiters(struct task_struct *p)
 59{
 60	return !RB_EMPTY_ROOT(&p->pi_waiters);
 61}
 62
 63static inline struct rt_mutex_waiter *
 64task_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
 75static inline struct task_struct *rt_mutex_owner(struct rt_mutex *lock)
 76{
 77	unsigned long owner = (unsigned long) READ_ONCE(lock->owner);
 78
 79	return (struct task_struct *) (owner & ~RT_MUTEX_HAS_WAITERS);
 80}
 81
 82/*
 83 * Constants for rt mutex functions which have a selectable deadlock
 84 * detection.
 85 *
 86 * RT_MUTEX_MIN_CHAINWALK:	Stops the lock chain walk when there are
 87 *				no further PI adjustments to be made.
 88 *
 89 * RT_MUTEX_FULL_CHAINWALK:	Invoke deadlock detection with a full
 90 *				walk of the lock chain.
 91 */
 92enum rtmutex_chainwalk {
 93	RT_MUTEX_MIN_CHAINWALK,
 94	RT_MUTEX_FULL_CHAINWALK,
 95};
 96
 97/*
 98 * PI-futex support (proxy locking functions, etc.):
 99 */
100extern struct task_struct *rt_mutex_next_owner(struct rt_mutex *lock);
101extern void rt_mutex_init_proxy_locked(struct rt_mutex *lock,
102				       struct task_struct *proxy_owner);
103extern void rt_mutex_proxy_unlock(struct rt_mutex *lock,
104				  struct task_struct *proxy_owner);
105extern int rt_mutex_start_proxy_lock(struct rt_mutex *lock,
106				     struct rt_mutex_waiter *waiter,
107				     struct task_struct *task);
108extern int rt_mutex_finish_proxy_lock(struct rt_mutex *lock,
109				      struct hrtimer_sleeper *to,
110				      struct rt_mutex_waiter *waiter);
111extern int rt_mutex_timed_futex_lock(struct rt_mutex *l, struct hrtimer_sleeper *to);
112extern bool rt_mutex_futex_unlock(struct rt_mutex *lock,
113				  struct wake_q_head *wqh);
114extern void rt_mutex_adjust_prio(struct task_struct *task);
115
116#ifdef CONFIG_DEBUG_RT_MUTEXES
117# include "rtmutex-debug.h"
118#else
119# include "rtmutex.h"
120#endif
121
122#endif