summaryrefslogtreecommitdiffstats
path: root/kernel/mutex-debug.c
blob: a92de145ed0dc28ea6c79bed3e8849b8e48e372d (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
/*
 * 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);
OpenPOWER on IntegriCloud