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/sched.h>
  17 #include <linux/delay.h>
  18 #include <linux/module.h>
  19 #include <linux/poison.h>
  20 #include <linux/spinlock.h>
  21 #include <linux/kallsyms.h>
  22 #include <linux/interrupt.h>
  23 #include <linux/debug_locks.h>
  24
  25 #include "mutex-debug.h"
  26
  27 /*
  28  * Must be called with lock->wait_lock held.
  29  */
  30 void debug_mutex_set_owner(struct mutex *lock, struct thread_info *new_owner)
  31 {
  32         lock->owner = new_owner;
  33 }
  34
  35 void debug_mutex_lock_common(struct mutex *lock, struct mutex_waiter *waiter)
  36 {
  37         memset(waiter, MUTEX_DEBUG_INIT, sizeof(*waiter));
  38         waiter->magic = waiter;
  39         INIT_LIST_HEAD(&waiter->list);
  40 }
  41
  42 void debug_mutex_wake_waiter(struct mutex *lock, struct mutex_waiter *waiter)
  43 {
  44         SMP_DEBUG_LOCKS_WARN_ON(!spin_is_locked(&lock->wait_lock));
  45         DEBUG_LOCKS_WARN_ON(list_empty(&lock->wait_list));
  46         DEBUG_LOCKS_WARN_ON(waiter->magic != waiter);
  47         DEBUG_LOCKS_WARN_ON(list_empty(&waiter->list));
  48 }
  49
  50 void debug_mutex_free_waiter(struct mutex_waiter *waiter)
  51 {
  52         DEBUG_LOCKS_WARN_ON(!list_empty(&waiter->list));
  53         memset(waiter, MUTEX_DEBUG_FREE, sizeof(*waiter));
  54 }
  55
  56 void debug_mutex_add_waiter(struct mutex *lock, struct mutex_waiter *waiter,
  57                             struct thread_info *ti)
  58 {
  59         SMP_DEBUG_LOCKS_WARN_ON(!spin_is_locked(&lock->wait_lock));
  60
  61         /* Mark the current thread as blocked on the lock: */
  62         ti->task->blocked_on = waiter;
  63         waiter->lock = lock;
  64 }
  65
  66 void mutex_remove_waiter(struct mutex *lock, struct mutex_waiter *waiter,
  67                          struct thread_info *ti)
  68 {
  69         DEBUG_LOCKS_WARN_ON(list_empty(&waiter->list));
  70         DEBUG_LOCKS_WARN_ON(waiter->task != ti->task);
  71         DEBUG_LOCKS_WARN_ON(ti->task->blocked_on != waiter);
  72         ti->task->blocked_on = NULL;
  73
  74         list_del_init(&waiter->list);
  75         waiter->task = NULL;
  76 }
  77
  78 void debug_mutex_unlock(struct mutex *lock)
  79 {
  80         DEBUG_LOCKS_WARN_ON(lock->owner != current_thread_info());
  81         DEBUG_LOCKS_WARN_ON(lock->magic != lock);
  82         DEBUG_LOCKS_WARN_ON(!lock->wait_list.prev && !lock->wait_list.next);
  83         DEBUG_LOCKS_WARN_ON(lock->owner != current_thread_info());
  84 }
  85
  86 void debug_mutex_init(struct mutex *lock, const char *name,
  87                       struct lock_class_key *key)
  88 {
  89 #ifdef CONFIG_DEBUG_LOCK_ALLOC
  90         /*
  91          * Make sure we are not reinitializing a held lock:
  92          */
  93         debug_check_no_locks_freed((void *)lock, sizeof(*lock));
  94         lockdep_init_map(&lock->dep_map, name, key, 0);
  95 #endif
  96         lock->owner = NULL;
  97         lock->magic = lock;
  98 }
  99
 100 /***
 101  * mutex_destroy - mark a mutex unusable
 102  * @lock: the mutex to be destroyed
 103  *
 104  * This function marks the mutex uninitialized, and any subsequent
 105  * use of the mutex is forbidden. The mutex must not be locked when
 106  * this function is called.
 107  */
 108 void fastcall mutex_destroy(struct mutex *lock)
 109 {
 110         DEBUG_LOCKS_WARN_ON(mutex_is_locked(lock));
 111         lock->magic = NULL;
 112 }
 113
 114 EXPORT_SYMBOL_GPL(mutex_destroy);