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  * 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
  25 extern 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  */
  47 struct 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  */
  63 static inline int rt_mutex_has_waiters(struct rt_mutex *lock)
  64 {
  65         return !RB_EMPTY_ROOT(&lock->waiters);
  66 }
  67
  68 static inline struct rt_mutex_waiter *
  69 rt_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
  80 static inline int task_has_pi_waiters(struct task_struct *p)
  81 {
  82         return !RB_EMPTY_ROOT(&p->pi_waiters);
  83 }
  84
  85 static inline struct rt_mutex_waiter *
  86 task_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
  98 static 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  * Constants for rt mutex functions which have a selectable deadlock
 106  * detection.
 107  *
 108  * RT_MUTEX_MIN_CHAINWALK:      Stops the lock chain walk when there are
 109  *                              no further PI adjustments to be made.
 110  *
 111  * RT_MUTEX_FULL_CHAINWALK:     Invoke deadlock detection with a full
 112  *                              walk of the lock chain.
 113  */
 114 enum rtmutex_chainwalk {
 115         RT_MUTEX_MIN_CHAINWALK,
 116         RT_MUTEX_FULL_CHAINWALK,
 117 };
 118
 119 /*
 120  * PI-futex support (proxy locking functions, etc.):
 121  */
 122 extern struct task_struct *rt_mutex_next_owner(struct rt_mutex *lock);
 123 extern void rt_mutex_init_proxy_locked(struct rt_mutex *lock,
 124                                        struct task_struct *proxy_owner);
 125 extern void rt_mutex_proxy_unlock(struct rt_mutex *lock,
 126                                   struct task_struct *proxy_owner);
 127 extern int rt_mutex_start_proxy_lock(struct rt_mutex *lock,
 128                                      struct rt_mutex_waiter *waiter,
 129                                      struct task_struct *task);
 130 extern int rt_mutex_finish_proxy_lock(struct rt_mutex *lock,
 131                                       struct hrtimer_sleeper *to,
 132                                       struct rt_mutex_waiter *waiter);
 133 extern int rt_mutex_timed_futex_lock(struct rt_mutex *l, struct hrtimer_sleeper *to);
 134
 135 #ifdef CONFIG_DEBUG_RT_MUTEXES
 136 # include "rtmutex-debug.h"
 137 #else
 138 # include "rtmutex.h"
 139 #endif
 140
 141 #endif