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); 121