1 /* 2 * Debugging code for mutexes 3 * 4 * Started by Ingo Molnar: 5 * 6 * Copyright (C) 2004, 2005, 2006 Red Hat, Inc., Ingo Molnar <[email protected]> 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 } 34 35 void debug_mutex_wake_waiter(struct mutex *lock, struct mutex_waiter *waiter) 36 { 37 lockdep_assert_held(&lock->wait_lock); 38 DEBUG_LOCKS_WARN_ON(list_empty(&lock->wait_list)); 39 DEBUG_LOCKS_WARN_ON(waiter->magic != waiter); 40 DEBUG_LOCKS_WARN_ON(list_empty(&waiter->list)); 41 } 42 43 void debug_mutex_free_waiter(struct mutex_waiter *waiter) 44 { 45 DEBUG_LOCKS_WARN_ON(!list_empty(&waiter->list)); 46 memset(waiter, MUTEX_DEBUG_FREE, sizeof(*waiter)); 47 } 48 49 void debug_mutex_add_waiter(struct mutex *lock, struct mutex_waiter *waiter, 50 struct task_struct *task) 51 { 52 lockdep_assert_held(&lock->wait_lock); 53 54 /* Mark the current thread as blocked on the lock: */ 55 task->blocked_on = waiter; 56 } 57 58 void debug_mutex_remove_waiter(struct mutex *lock, struct mutex_waiter *waiter, 59 struct task_struct *task) 60 { 61 DEBUG_LOCKS_WARN_ON(list_empty(&waiter->list)); 62 DEBUG_LOCKS_WARN_ON(waiter->task != task); 63 DEBUG_LOCKS_WARN_ON(task->blocked_on != waiter); 64 task->blocked_on = NULL; 65 66 INIT_LIST_HEAD(&waiter->list); 67 waiter->task = NULL; 68 } 69 70 void debug_mutex_unlock(struct mutex *lock) 71 { 72 if (likely(debug_locks)) { 73 DEBUG_LOCKS_WARN_ON(lock->magic != lock); 74 DEBUG_LOCKS_WARN_ON(!lock->wait_list.prev && !lock->wait_list.next); 75 } 76 } 77 78 void debug_mutex_init(struct mutex *lock, const char *name, 79 struct lock_class_key *key) 80 { 81 #ifdef CONFIG_DEBUG_LOCK_ALLOC 82 /* 83 * Make sure we are not reinitializing a held lock: 84 */ 85 debug_check_no_locks_freed((void *)lock, sizeof(*lock)); 86 lockdep_init_map_wait(&lock->dep_map, name, key, 0, LD_WAIT_SLEEP); 87 #endif 88 lock->magic = lock; 89 } 90 91 /*** 92 * mutex_destroy - mark a mutex unusable 93 * @lock: the mutex to be destroyed 94 * 95 * This function marks the mutex uninitialized, and any subsequent 96 * use of the mutex is forbidden. The mutex must not be locked when 97 * this function is called. 98 */ 99 void mutex_destroy(struct mutex *lock) 100 { 101 DEBUG_LOCKS_WARN_ON(mutex_is_locked(lock)); 102 lock->magic = NULL; 103 } 104 105 EXPORT_SYMBOL_GPL(mutex_destroy); 106