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(!lock->first_waiter); 41 DEBUG_LOCKS_WARN_ON(waiter->magic != waiter); 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 /* Current thread can't be already blocked (since it's executing!) */ 56 DEBUG_LOCKS_WARN_ON(get_task_blocked_on(task)); 57 } 58 59 void debug_mutex_remove_waiter(struct mutex *lock, struct mutex_waiter *waiter, 60 struct task_struct *task) 61 { 62 struct mutex *blocked_on = get_task_blocked_on(task); 63 64 DEBUG_LOCKS_WARN_ON(waiter->task != task); 65 DEBUG_LOCKS_WARN_ON(blocked_on && blocked_on != lock); 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 } 76 } 77 78 void debug_mutex_init(struct mutex *lock) 79 { 80 lock->magic = lock; 81 } 82 83 static void devm_mutex_release(void *res) 84 { 85 mutex_destroy(res); 86 } 87 88 int __devm_mutex_init(struct device *dev, struct mutex *lock) 89 { 90 return devm_add_action_or_reset(dev, devm_mutex_release, lock); 91 } 92 EXPORT_SYMBOL_GPL(__devm_mutex_init); 93 94 /*** 95 * mutex_destroy - mark a mutex unusable 96 * @lock: the mutex to be destroyed 97 * 98 * This function marks the mutex uninitialized, and any subsequent 99 * use of the mutex is forbidden. The mutex must not be locked when 100 * this function is called. 101 */ 102 void mutex_destroy(struct mutex *lock) 103 { 104 DEBUG_LOCKS_WARN_ON(mutex_is_locked(lock)); 105 lock->magic = NULL; 106 } 107 108 EXPORT_SYMBOL_GPL(mutex_destroy); 109