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/device.h>
  16 #include <linux/export.h>
  17 #include <linux/poison.h>
  18 #include <linux/sched.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.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         waiter->ww_ctx = MUTEX_POISON_WW_CTX;
  35 }
  36
  37 void debug_mutex_wake_waiter(struct mutex *lock, struct mutex_waiter *waiter)
  38 {
  39         lockdep_assert_held(&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         lockdep_assert_held(&lock->wait_lock);
  55
  56         /* Mark the current thread as blocked on the lock: */
  57         task->blocked_on = waiter;
  58 }
  59
  60 void debug_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         INIT_LIST_HEAD(&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                 DEBUG_LOCKS_WARN_ON(!lock->wait_list.prev && !lock->wait_list.next);
  77         }
  78 }
  79
  80 void debug_mutex_init(struct mutex *lock, const char *name,
  81                       struct lock_class_key *key)
  82 {
  83 #ifdef CONFIG_DEBUG_LOCK_ALLOC
  84         /*
  85          * Make sure we are not reinitializing a held lock:
  86          */
  87         debug_check_no_locks_freed((void *)lock, sizeof(*lock));
  88         lockdep_init_map_wait(&lock->dep_map, name, key, 0, LD_WAIT_SLEEP);
  89 #endif
  90         lock->magic = lock;
  91 }
  92
  93 static void devm_mutex_release(void *res)
  94 {
  95         mutex_destroy(res);
  96 }
  97
  98 int __devm_mutex_init(struct device *dev, struct mutex *lock)
  99 {
 100         return devm_add_action_or_reset(dev, devm_mutex_release, lock);
 101 }
 102 EXPORT_SYMBOL_GPL(__devm_mutex_init);
 103
 104 /***
 105  * mutex_destroy - mark a mutex unusable
 106  * @lock: the mutex to be destroyed
 107  *
 108  * This function marks the mutex uninitialized, and any subsequent
 109  * use of the mutex is forbidden. The mutex must not be locked when
 110  * this function is called.
 111  */
 112 void mutex_destroy(struct mutex *lock)
 113 {
 114         DEBUG_LOCKS_WARN_ON(mutex_is_locked(lock));
 115         lock->magic = NULL;
 116 }
 117
 118 EXPORT_SYMBOL_GPL(mutex_destroy);