kernel/locking/mutex-debug.c

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