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         u64 deadline;
  38 };
  39
  40 /*
  41  * Various helpers to access the waiters-tree:
  42  */
  43 static inline int rt_mutex_has_waiters(struct rt_mutex *lock)
  44 {
  45         return !RB_EMPTY_ROOT(&lock->waiters);
  46 }
  47
  48 static inline struct rt_mutex_waiter *
  49 rt_mutex_top_waiter(struct rt_mutex *lock)
  50 {
  51         struct rt_mutex_waiter *w;
  52
  53         w = rb_entry(lock->waiters_leftmost, struct rt_mutex_waiter,
  54                      tree_entry);
  55         BUG_ON(w->lock != lock);
  56
  57         return w;
  58 }
  59
  60 static inline int task_has_pi_waiters(struct task_struct *p)
  61 {
  62         return !RB_EMPTY_ROOT(&p->pi_waiters);
  63 }
  64
  65 static inline struct rt_mutex_waiter *
  66 task_top_pi_waiter(struct task_struct *p)
  67 {
  68         return rb_entry(p->pi_waiters_leftmost, struct rt_mutex_waiter,
  69                         pi_tree_entry);
  70 }
  71
  72 /*
  73  * lock->owner state tracking:
  74  */
  75 #define RT_MUTEX_HAS_WAITERS    1UL
  76
  77 static inline struct task_struct *rt_mutex_owner(struct rt_mutex *lock)
  78 {
  79         unsigned long owner = (unsigned long) READ_ONCE(lock->owner);
  80
  81         return (struct task_struct *) (owner & ~RT_MUTEX_HAS_WAITERS);
  82 }
  83
  84 /*
  85  * Constants for rt mutex functions which have a selectable deadlock
  86  * detection.
  87  *
  88  * RT_MUTEX_MIN_CHAINWALK:      Stops the lock chain walk when there are
  89  *                              no further PI adjustments to be made.
  90  *
  91  * RT_MUTEX_FULL_CHAINWALK:     Invoke deadlock detection with a full
  92  *                              walk of the lock chain.
  93  */
  94 enum rtmutex_chainwalk {
  95         RT_MUTEX_MIN_CHAINWALK,
  96         RT_MUTEX_FULL_CHAINWALK,
  97 };
  98
  99 /*
 100  * PI-futex support (proxy locking functions, etc.):
 101  */
 102 extern struct task_struct *rt_mutex_next_owner(struct rt_mutex *lock);
 103 extern void rt_mutex_init_proxy_locked(struct rt_mutex *lock,
 104                                        struct task_struct *proxy_owner);
 105 extern void rt_mutex_proxy_unlock(struct rt_mutex *lock,
 106                                   struct task_struct *proxy_owner);
 107 extern void rt_mutex_init_waiter(struct rt_mutex_waiter *waiter);
 108 extern int __rt_mutex_start_proxy_lock(struct rt_mutex *lock,
 109                                      struct rt_mutex_waiter *waiter,
 110                                      struct task_struct *task);
 111 extern int rt_mutex_start_proxy_lock(struct rt_mutex *lock,
 112                                      struct rt_mutex_waiter *waiter,
 113                                      struct task_struct *task);
 114 extern int rt_mutex_wait_proxy_lock(struct rt_mutex *lock,
 115                                struct hrtimer_sleeper *to,
 116                                struct rt_mutex_waiter *waiter);
 117 extern bool rt_mutex_cleanup_proxy_lock(struct rt_mutex *lock,
 118                                  struct rt_mutex_waiter *waiter);
 119
 120 extern int rt_mutex_futex_trylock(struct rt_mutex *l);
 121
 122 extern void rt_mutex_futex_unlock(struct rt_mutex *lock);
 123 extern bool __rt_mutex_futex_unlock(struct rt_mutex *lock,
 124                                  struct wake_q_head *wqh);
 125
 126 extern void rt_mutex_postunlock(struct wake_q_head *wake_q);
 127
 128 #ifdef CONFIG_DEBUG_RT_MUTEXES
 129 # include "rtmutex-debug.h"
 130 #else
 131 # include "rtmutex.h"
 132 #endif
 133
 134 #endif