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/*
* kernel/mutex-debug.c
*
* Debugging code for mutexes
*
* Started by Ingo Molnar:
*
* Copyright (C) 2004, 2005, 2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
*
* lock debugging, locking tree, deadlock detection started by:
*
* Copyright (C) 2004, LynuxWorks, Inc., Igor Manyilov, Bill Huey
* Released under the General Public License (GPL).
*/
#include <linux/mutex.h>
#include <linux/sched.h>
#include <linux/delay.h>
#include <linux/module.h>
#include <linux/poison.h>
#include <linux/spinlock.h>
#include <linux/kallsyms.h>
#include <linux/interrupt.h>
#include "mutex-debug.h"
/*
* We need a global lock when we walk through the multi-process
* lock tree. Only used in the deadlock-debugging case.
*/
DEFINE_SPINLOCK(debug_mutex_lock);
/*
* All locks held by all tasks, in a single global list:
*/
LIST_HEAD(debug_mutex_held_locks);
/*
* In the debug case we carry the caller's instruction pointer into
* other functions, but we dont want the function argument overhead
* in the nondebug case - hence these macros:
*/
#define __IP_DECL__ , unsigned long ip
#define __IP__ , ip
#define __RET_IP__ , (unsigned long)__builtin_return_address(0)
/*
* "mutex debugging enabled" flag. We turn it off when we detect
* the first problem because we dont want to recurse back
* into the tracing code when doing error printk or
* executing a BUG():
*/
int debug_mutex_on = 1;
/*
* Must be called with lock->wait_lock held.
*/
void debug_mutex_set_owner(struct mutex *lock,
struct thread_info *new_owner __IP_DECL__)
{
lock->owner = new_owner;
DEBUG_LOCKS_WARN_ON(!list_empty(&lock->held_list));
if (debug_mutex_on) {
list_add_tail(&lock->held_list, &debug_mutex_held_locks);
lock->acquire_ip = ip;
}
}
void debug_mutex_init_waiter(struct mutex_waiter *waiter)
{
memset(waiter, MUTEX_DEBUG_INIT, sizeof(*waiter));
waiter->magic = waiter;
INIT_LIST_HEAD(&waiter->list);
}
void debug_mutex_wake_waiter(struct mutex *lock, struct mutex_waiter *waiter)
{
SMP_DEBUG_LOCKS_WARN_ON(!spin_is_locked(&lock->wait_lock));
DEBUG_LOCKS_WARN_ON(list_empty(&lock->wait_list));
DEBUG_LOCKS_WARN_ON(waiter->magic != waiter);
DEBUG_LOCKS_WARN_ON(list_empty(&waiter->list));
}
void debug_mutex_free_waiter(struct mutex_waiter *waiter)
{
DEBUG_LOCKS_WARN_ON(!list_empty(&waiter->list));
memset(waiter, MUTEX_DEBUG_FREE, sizeof(*waiter));
}
void debug_mutex_add_waiter(struct mutex *lock, struct mutex_waiter *waiter,
struct thread_info *ti __IP_DECL__)
{
SMP_DEBUG_LOCKS_WARN_ON(!spin_is_locked(&lock->wait_lock));
/* Mark the current thread as blocked on the lock: */
ti->task->blocked_on = waiter;
waiter->lock = lock;
}
void mutex_remove_waiter(struct mutex *lock, struct mutex_waiter *waiter,
struct thread_info *ti)
{
DEBUG_LOCKS_WARN_ON(list_empty(&waiter->list));
DEBUG_LOCKS_WARN_ON(waiter->task != ti->task);
DEBUG_LOCKS_WARN_ON(ti->task->blocked_on != waiter);
ti->task->blocked_on = NULL;
list_del_init(&waiter->list);
waiter->task = NULL;
}
void debug_mutex_unlock(struct mutex *lock)
{
DEBUG_LOCKS_WARN_ON(lock->magic != lock);
DEBUG_LOCKS_WARN_ON(!lock->wait_list.prev && !lock->wait_list.next);
DEBUG_LOCKS_WARN_ON(lock->owner != current_thread_info());
if (debug_mutex_on) {
DEBUG_LOCKS_WARN_ON(list_empty(&lock->held_list));
list_del_init(&lock->held_list);
}
}
void debug_mutex_init(struct mutex *lock, const char *name)
{
/*
* Make sure we are not reinitializing a held lock:
*/
mutex_debug_check_no_locks_freed((void *)lock, sizeof(*lock));
lock->owner = NULL;
INIT_LIST_HEAD(&lock->held_list);
lock->name = name;
lock->magic = lock;
}
/***
* mutex_destroy - mark a mutex unusable
* @lock: the mutex to be destroyed
*
* This function marks the mutex uninitialized, and any subsequent
* use of the mutex is forbidden. The mutex must not be locked when
* this function is called.
*/
void fastcall mutex_destroy(struct mutex *lock)
{
DEBUG_LOCKS_WARN_ON(mutex_is_locked(lock));
lock->magic = NULL;
}
EXPORT_SYMBOL_GPL(mutex_destroy);
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