kernel/locking/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/export.h>
  18 #include <linux/poison.h>
  19 #include <linux/sched.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_lock_common(struct mutex *lock, struct mutex_waiter *waiter)
  31 {
  32         memset(waiter, MUTEX_DEBUG_INIT, sizeof(*waiter));
  33         waiter->magic = waiter;
  34         INIT_LIST_HEAD(&waiter->list);
  35 }
  36
  37 void debug_mutex_wake_waiter(struct mutex *lock, struct mutex_waiter *waiter)
  38 {
  39         SMP_DEBUG_LOCKS_WARN_ON(!spin_is_locked(&lock->wait_lock));
  40         DEBUG_LOCKS_WARN_ON(list_empty(&lock->wait_list));
  41         DEBUG_LOCKS_WARN_ON(waiter->magic != waiter);
  42         DEBUG_LOCKS_WARN_ON(list_empty(&waiter->list));
  43 }
  44
  45 void debug_mutex_free_waiter(struct mutex_waiter *waiter)
  46 {
  47         DEBUG_LOCKS_WARN_ON(!list_empty(&waiter->list));
  48         memset(waiter, MUTEX_DEBUG_FREE, sizeof(*waiter));
  49 }
  50
  51 void debug_mutex_add_waiter(struct mutex *lock, struct mutex_waiter *waiter,
  52                             struct task_struct *task)
  53 {
  54         SMP_DEBUG_LOCKS_WARN_ON(!spin_is_locked(&lock->wait_lock));
  55
  56         /* Mark the current thread as blocked on the lock: */
  57         task->blocked_on = waiter;
  58 }
  59
  60 void mutex_remove_waiter(struct mutex *lock, struct mutex_waiter *waiter,
  61                          struct task_struct *task)
  62 {
  63         DEBUG_LOCKS_WARN_ON(list_empty(&waiter->list));
  64         DEBUG_LOCKS_WARN_ON(waiter->task != task);
  65         DEBUG_LOCKS_WARN_ON(task->blocked_on != waiter);
  66         task->blocked_on = NULL;
  67
  68         list_del_init(&waiter->list);
  69         waiter->task = NULL;
  70 }
  71
  72 void debug_mutex_unlock(struct mutex *lock)
  73 {
  74         if (likely(debug_locks)) {
  75                 DEBUG_LOCKS_WARN_ON(lock->magic != lock);
  76
  77                 if (!lock->owner)
  78                         DEBUG_LOCKS_WARN_ON(!lock->owner);
  79                 else
  80                         DEBUG_LOCKS_WARN_ON(lock->owner != current);
  81
  82                 DEBUG_LOCKS_WARN_ON(!lock->wait_list.prev && !lock->wait_list.next);
  83         }
  84
  85         /*
  86          * __mutex_slowpath_needs_to_unlock() is explicitly 0 for debug
  87          * mutexes so that we can do it here after we've verified state.
  88          */
  89         mutex_clear_owner(lock);
  90         atomic_set(&lock->count, 1);
  91 }
  92
  93 void debug_mutex_init(struct mutex *lock, const char *name,
  94                       struct lock_class_key *key)
  95 {
  96 #ifdef CONFIG_DEBUG_LOCK_ALLOC
  97         /*
  98          * Make sure we are not reinitializing a held lock:
  99          */
 100         debug_check_no_locks_freed((void *)lock, sizeof(*lock));
 101         lockdep_init_map(&lock->dep_map, name, key, 0);
 102 #endif
 103         lock->magic = lock;
 104 }
 105
 106 /***
 107  * mutex_destroy - mark a mutex unusable
 108  * @lock: the mutex to be destroyed
 109  *
 110  * This function marks the mutex uninitialized, and any subsequent
 111  * use of the mutex is forbidden. The mutex must not be locked when
 112  * this function is called.
 113  */
 114 void mutex_destroy(struct mutex *lock)
 115 {
 116         DEBUG_LOCKS_WARN_ON(mutex_is_locked(lock));
 117         lock->magic = NULL;
 118 }
 119
 120 EXPORT_SYMBOL_GPL(mutex_destroy);