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/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 waiter->ww_ctx = MUTEX_POISON_WW_CTX; 34 } 35 36 void debug_mutex_wake_waiter(struct mutex *lock, struct mutex_waiter *waiter) 37 { 38 lockdep_assert_held(&lock->wait_lock); 39 DEBUG_LOCKS_WARN_ON(list_empty(&lock->wait_list)); 40 DEBUG_LOCKS_WARN_ON(waiter->magic != waiter); 41 DEBUG_LOCKS_WARN_ON(list_empty(&waiter->list)); 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 /* Mark the current thread as blocked on the lock: */ 56 task->blocked_on = waiter; 57 } 58 59 void debug_mutex_remove_waiter(struct mutex *lock, struct mutex_waiter *waiter, 60 struct task_struct *task) 61 { 62 DEBUG_LOCKS_WARN_ON(list_empty(&waiter->list)); 63 DEBUG_LOCKS_WARN_ON(waiter->task != task); 64 DEBUG_LOCKS_WARN_ON(task->blocked_on != waiter); 65 task->blocked_on = NULL; 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 DEBUG_LOCKS_WARN_ON(!lock->wait_list.prev && !lock->wait_list.next); 76 } 77 } 78 79 void debug_mutex_init(struct mutex *lock, const char *name, 80 struct lock_class_key *key) 81 { 82 #ifdef CONFIG_DEBUG_LOCK_ALLOC 83 /* 84 * Make sure we are not reinitializing a held lock: 85 */ 86 debug_check_no_locks_freed((void *)lock, sizeof(*lock)); 87 lockdep_init_map_wait(&lock->dep_map, name, key, 0, LD_WAIT_SLEEP); 88 #endif 89 lock->magic = lock; 90 } 91 92 /*** 93 * mutex_destroy - mark a mutex unusable 94 * @lock: the mutex to be destroyed 95 * 96 * This function marks the mutex uninitialized, and any subsequent 97 * use of the mutex is forbidden. The mutex must not be locked when 98 * this function is called. 99 */ 100 void mutex_destroy(struct mutex *lock) 101 { 102 DEBUG_LOCKS_WARN_ON(mutex_is_locked(lock)); 103 lock->magic = NULL; 104 } 105 106 EXPORT_SYMBOL_GPL(mutex_destroy); 107