kernel/mutex-debug.c

   1 /*
   2  * kernel/mutex-debug.c
   3  *
   4  * Debugging code for mutexes
   5  *
   6  * Started by Ingo Molnar:
   7  *
   8  *  Copyright (C) 2004, 2005, 2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
   9  *
  10  * lock debugging, locking tree, deadlock detection started by:
  11  *
  12  *  Copyright (C) 2004, LynuxWorks, Inc., Igor Manyilov, Bill Huey
  13  *  Released under the General Public License (GPL).
  14  */
  15 #include <linux/mutex.h>
  16 #include <linux/delay.h>
  17 #include <linux/module.h>
  18 #include <linux/poison.h>
  19 #include <linux/spinlock.h>
  20 #include <linux/kallsyms.h>
  21 #include <linux/interrupt.h>
  22 #include <linux/debug_locks.h>
  23
  24 #include "mutex-debug.h"
  25
  26 /*
  27  * Must be called with lock->wait_lock held.
  28  */
  29 void debug_mutex_set_owner(struct mutex *lock, struct thread_info *new_owner)
  30 {
  31         lock->owner = new_owner;
  32 }
  33
  34 void debug_mutex_lock_common(struct mutex *lock, struct mutex_waiter *waiter)
  35 {
  36         memset(waiter, MUTEX_DEBUG_INIT, sizeof(*waiter));
  37         waiter->magic = waiter;
  38         INIT_LIST_HEAD(&waiter->list);
  39 }
  40
  41 void debug_mutex_wake_waiter(struct mutex *lock, struct mutex_waiter *waiter)
  42 {
  43         SMP_DEBUG_LOCKS_WARN_ON(!spin_is_locked(&lock->wait_lock));
  44         DEBUG_LOCKS_WARN_ON(list_empty(&lock->wait_list));
  45         DEBUG_LOCKS_WARN_ON(waiter->magic != waiter);
  46         DEBUG_LOCKS_WARN_ON(list_empty(&waiter->list));
  47 }
  48
  49 void debug_mutex_free_waiter(struct mutex_waiter *waiter)
  50 {
  51         DEBUG_LOCKS_WARN_ON(!list_empty(&waiter->list));
  52         memset(waiter, MUTEX_DEBUG_FREE, sizeof(*waiter));
  53 }
  54
  55 void debug_mutex_add_waiter(struct mutex *lock, struct mutex_waiter *waiter,
  56                             struct thread_info *ti)
  57 {
  58         SMP_DEBUG_LOCKS_WARN_ON(!spin_is_locked(&lock->wait_lock));
  59
  60         /* Mark the current thread as blocked on the lock: */
  61         ti->task->blocked_on = waiter;
  62         waiter->lock = lock;
  63 }
  64
  65 void mutex_remove_waiter(struct mutex *lock, struct mutex_waiter *waiter,
  66                          struct thread_info *ti)
  67 {
  68         DEBUG_LOCKS_WARN_ON(list_empty(&waiter->list));
  69         DEBUG_LOCKS_WARN_ON(waiter->task != ti->task);
  70         DEBUG_LOCKS_WARN_ON(ti->task->blocked_on != waiter);
  71         ti->task->blocked_on = NULL;
  72
  73         list_del_init(&waiter->list);
  74         waiter->task = NULL;
  75 }
  76
  77 void debug_mutex_unlock(struct mutex *lock)
  78 {
  79         if (unlikely(!debug_locks))
  80                 return;
  81
  82         DEBUG_LOCKS_WARN_ON(lock->owner != current_thread_info());
  83         DEBUG_LOCKS_WARN_ON(lock->magic != lock);
  84         DEBUG_LOCKS_WARN_ON(!lock->wait_list.prev && !lock->wait_list.next);
  85         DEBUG_LOCKS_WARN_ON(lock->owner != current_thread_info());
  86 }
  87
  88 void debug_mutex_init(struct mutex *lock, const char *name,
  89                       struct lock_class_key *key)
  90 {
  91 #ifdef CONFIG_DEBUG_LOCK_ALLOC
  92         /*
  93          * Make sure we are not reinitializing a held lock:
  94          */
  95         debug_check_no_locks_freed((void *)lock, sizeof(*lock));
  96         lockdep_init_map(&lock->dep_map, name, key, 0);
  97 #endif
  98         lock->owner = NULL;
  99         lock->magic = lock;
 100 }
 101
 102 /***
 103  * mutex_destroy - mark a mutex unusable
 104  * @lock: the mutex to be destroyed
 105  *
 106  * This function marks the mutex uninitialized, and any subsequent
 107  * use of the mutex is forbidden. The mutex must not be locked when
 108  * this function is called.
 109  */
 110 void mutex_destroy(struct mutex *lock)
 111 {
 112         DEBUG_LOCKS_WARN_ON(mutex_is_locked(lock));
 113         lock->magic = NULL;
 114 }
 115
 116 EXPORT_SYMBOL_GPL(mutex_destroy);