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_lock_common(struct mutex *lock, struct mutex_waiter *waiter)
  30 {
  31         memset(waiter, MUTEX_DEBUG_INIT, sizeof(*waiter));
  32         waiter->magic = waiter;
  33         INIT_LIST_HEAD(&waiter->list);
  34 }
  35
  36 void debug_mutex_wake_waiter(struct mutex *lock, struct mutex_waiter *waiter)
  37 {
  38         SMP_DEBUG_LOCKS_WARN_ON(!spin_is_locked(&lock->wait_lock));
  39         DEBUG_LOCKS_WARN_ON(list_empty(&lock->wait_list));
  40         DEBUG_LOCKS_WARN_ON(waiter->magic != waiter);
  41         DEBUG_LOCKS_WARN_ON(list_empty(&waiter->list));
  42 }
  43
  44 void debug_mutex_free_waiter(struct mutex_waiter *waiter)
  45 {
  46         DEBUG_LOCKS_WARN_ON(!list_empty(&waiter->list));
  47         memset(waiter, MUTEX_DEBUG_FREE, sizeof(*waiter));
  48 }
  49
  50 void debug_mutex_add_waiter(struct mutex *lock, struct mutex_waiter *waiter,
  51                             struct thread_info *ti)
  52 {
  53         SMP_DEBUG_LOCKS_WARN_ON(!spin_is_locked(&lock->wait_lock));
  54
  55         /* Mark the current thread as blocked on the lock: */
  56         ti->task->blocked_on = waiter;
  57 }
  58
  59 void mutex_remove_waiter(struct mutex *lock, struct mutex_waiter *waiter,
  60                          struct thread_info *ti)
  61 {
  62         DEBUG_LOCKS_WARN_ON(list_empty(&waiter->list));
  63         DEBUG_LOCKS_WARN_ON(waiter->task != ti->task);
  64         DEBUG_LOCKS_WARN_ON(ti->task->blocked_on != waiter);
  65         ti->task->blocked_on = NULL;
  66
  67         list_del_init(&waiter->list);
  68         waiter->task = NULL;
  69 }
  70
  71 void debug_mutex_unlock(struct mutex *lock)
  72 {
  73         if (unlikely(!debug_locks))
  74                 return;
  75
  76         DEBUG_LOCKS_WARN_ON(lock->magic != lock);
  77         DEBUG_LOCKS_WARN_ON(lock->owner != current_thread_info());
  78         DEBUG_LOCKS_WARN_ON(!lock->wait_list.prev && !lock->wait_list.next);
  79         mutex_clear_owner(lock);
  80 }
  81
  82 void debug_mutex_init(struct mutex *lock, const char *name,
  83                       struct lock_class_key *key)
  84 {
  85 #ifdef CONFIG_DEBUG_LOCK_ALLOC
  86         /*
  87          * Make sure we are not reinitializing a held lock:
  88          */
  89         debug_check_no_locks_freed((void *)lock, sizeof(*lock));
  90         lockdep_init_map(&lock->dep_map, name, key, 0);
  91 #endif
  92         lock->magic = lock;
  93 }
  94
  95 /***
  96  * mutex_destroy - mark a mutex unusable
  97  * @lock: the mutex to be destroyed
  98  *
  99  * This function marks the mutex uninitialized, and any subsequent
 100  * use of the mutex is forbidden. The mutex must not be locked when
 101  * this function is called.
 102  */
 103 void mutex_destroy(struct mutex *lock)
 104 {
 105         DEBUG_LOCKS_WARN_ON(mutex_is_locked(lock));
 106         lock->magic = NULL;
 107 }
 108
 109 EXPORT_SYMBOL_GPL(mutex_destroy);