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 #include <linux/sched/wake_q.h>
  17
  18 /*
  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.
  21  *
  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
  25  */
  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
  32         unsigned long           ip;
  33         struct pid              *deadlock_task_pid;
  34         struct rt_mutex         *deadlock_lock;
  35 #endif
  36         int prio;
  37 };
  38
  39 /*
  40  * Various helpers to access the waiters-tree:
  41  */
  42 static inline int rt_mutex_has_waiters(struct rt_mutex *lock)
  43 {
  44         return !RB_EMPTY_ROOT(&lock->waiters);
  45 }
  46
  47 static inline struct rt_mutex_waiter *
  48 rt_mutex_top_waiter(struct rt_mutex *lock)
  49 {
  50         struct rt_mutex_waiter *w;
  51
  52         w = rb_entry(lock->waiters_leftmost, struct rt_mutex_waiter,
  53                      tree_entry);
  54         BUG_ON(w->lock != lock);
  55
  56         return w;
  57 }
  58
  59 static inline int task_has_pi_waiters(struct task_struct *p)
  60 {
  61         return !RB_EMPTY_ROOT(&p->pi_waiters);
  62 }
  63
  64 static inline struct rt_mutex_waiter *
  65 task_top_pi_waiter(struct task_struct *p)
  66 {
  67         return rb_entry(p->pi_waiters_leftmost, struct rt_mutex_waiter,
  68                         pi_tree_entry);
  69 }
  70
  71 /*
  72  * lock->owner state tracking:
  73  */
  74 #define RT_MUTEX_HAS_WAITERS    1UL
  75
  76 static inline struct task_struct *rt_mutex_owner(struct rt_mutex *lock)
  77 {
  78         unsigned long owner = (unsigned long) READ_ONCE(lock->owner);
  79
  80         return (struct task_struct *) (owner & ~RT_MUTEX_HAS_WAITERS);
  81 }
  82
  83 /*
  84  * Constants for rt mutex functions which have a selectable deadlock
  85  * detection.
  86  *
  87  * RT_MUTEX_MIN_CHAINWALK:      Stops the lock chain walk when there are
  88  *                              no further PI adjustments to be made.
  89  *
  90  * RT_MUTEX_FULL_CHAINWALK:     Invoke deadlock detection with a full
  91  *                              walk of the lock chain.
  92  */
  93 enum rtmutex_chainwalk {
  94         RT_MUTEX_MIN_CHAINWALK,
  95         RT_MUTEX_FULL_CHAINWALK,
  96 };
  97
  98 /*
  99  * PI-futex support (proxy locking functions, etc.):
 100  */
 101 extern struct task_struct *rt_mutex_next_owner(struct rt_mutex *lock);
 102 extern void rt_mutex_init_proxy_locked(struct rt_mutex *lock,
 103                                        struct task_struct *proxy_owner);
 104 extern void rt_mutex_proxy_unlock(struct rt_mutex *lock,
 105                                   struct task_struct *proxy_owner);
 106 extern int rt_mutex_start_proxy_lock(struct rt_mutex *lock,
 107                                      struct rt_mutex_waiter *waiter,
 108                                      struct task_struct *task);
 109 extern int rt_mutex_finish_proxy_lock(struct rt_mutex *lock,
 110                                       struct hrtimer_sleeper *to,
 111                                       struct rt_mutex_waiter *waiter);
 112 extern int rt_mutex_timed_futex_lock(struct rt_mutex *l, struct hrtimer_sleeper *to);
 113 extern bool rt_mutex_futex_unlock(struct rt_mutex *lock,
 114                                   struct wake_q_head *wqh);
 115 extern void rt_mutex_adjust_prio(struct task_struct *task);
 116
 117 #ifdef CONFIG_DEBUG_RT_MUTEXES
 118 # include "rtmutex-debug.h"
 119 #else
 120 # include "rtmutex.h"
 121 #endif
 122
 123 #endif