kernel/locking/rtmutex_common.h

   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 };
  37
  38 /*
  39  * Various helpers to access the waiters-tree:
  40  */
  41 static inline int rt_mutex_has_waiters(struct rt_mutex *lock)
  42 {
  43         return !RB_EMPTY_ROOT(&lock->waiters);
  44 }
  45
  46 static inline struct rt_mutex_waiter *
  47 rt_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
  58 static inline int task_has_pi_waiters(struct task_struct *p)
  59 {
  60         return !RB_EMPTY_ROOT(&p->pi_waiters);
  61 }
  62
  63 static inline struct rt_mutex_waiter *
  64 task_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
  75 static 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  */
  92 enum rtmutex_chainwalk {
  93         RT_MUTEX_MIN_CHAINWALK,
  94         RT_MUTEX_FULL_CHAINWALK,
  95 };
  96
  97 /*
  98  * PI-futex support (proxy locking functions, etc.):
  99  */
 100 extern struct task_struct *rt_mutex_next_owner(struct rt_mutex *lock);
 101 extern void rt_mutex_init_proxy_locked(struct rt_mutex *lock,
 102                                        struct task_struct *proxy_owner);
 103 extern void rt_mutex_proxy_unlock(struct rt_mutex *lock,
 104                                   struct task_struct *proxy_owner);
 105 extern int rt_mutex_start_proxy_lock(struct rt_mutex *lock,
 106                                      struct rt_mutex_waiter *waiter,
 107                                      struct task_struct *task);
 108 extern int rt_mutex_finish_proxy_lock(struct rt_mutex *lock,
 109                                       struct hrtimer_sleeper *to,
 110                                       struct rt_mutex_waiter *waiter);
 111 extern int rt_mutex_timed_futex_lock(struct rt_mutex *l, struct hrtimer_sleeper *to);
 112 extern bool rt_mutex_futex_unlock(struct rt_mutex *lock,
 113                                   struct wake_q_head *wqh);
 114 extern 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