1/*
2 * Copyright 2005, Red Hat, Inc., Ingo Molnar
3 * Released under the General Public License (GPL).
4 *
5 * This file contains the spinlock/rwlock implementations for
6 * DEBUG_SPINLOCK.
7 */
8
9#include <linux/spinlock.h>
10#include <linux/nmi.h>
11#include <linux/interrupt.h>
12#include <linux/debug_locks.h>
13#include <linux/delay.h>
14#include <linux/export.h>
15
16void __raw_spin_lock_init(raw_spinlock_t *lock, const char *name,
17			  struct lock_class_key *key, short inner)
18{
19#ifdef CONFIG_DEBUG_LOCK_ALLOC
20	/*
21	 * Make sure we are not reinitializing a held lock:
22	 */
23	debug_check_no_locks_freed((void *)lock, sizeof(*lock));
24	lockdep_init_map_wait(&lock->dep_map, name, key, 0, inner);
25#endif
26	lock->raw_lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
27	lock->magic = SPINLOCK_MAGIC;
28	lock->owner = SPINLOCK_OWNER_INIT;
29	lock->owner_cpu = -1;
30}
31
32EXPORT_SYMBOL(__raw_spin_lock_init);
33
34#ifndef CONFIG_PREEMPT_RT
35void __rwlock_init(rwlock_t *lock, const char *name,
36		   struct lock_class_key *key)
37{
38#ifdef CONFIG_DEBUG_LOCK_ALLOC
39	/*
40	 * Make sure we are not reinitializing a held lock:
41	 */
42	debug_check_no_locks_freed((void *)lock, sizeof(*lock));
43	lockdep_init_map_wait(&lock->dep_map, name, key, 0, LD_WAIT_CONFIG);
44#endif
45	lock->raw_lock = (arch_rwlock_t) __ARCH_RW_LOCK_UNLOCKED;
46	lock->magic = RWLOCK_MAGIC;
47	lock->owner = SPINLOCK_OWNER_INIT;
48	lock->owner_cpu = -1;
49}
50
51EXPORT_SYMBOL(__rwlock_init);
52#endif
53
54static void spin_dump(raw_spinlock_t *lock, const char *msg)
55{
56	struct task_struct *owner = READ_ONCE(lock->owner);
57
58	if (owner == SPINLOCK_OWNER_INIT)
59		owner = NULL;
60	printk(KERN_EMERG "BUG: spinlock %s on CPU#%d, %s/%d\n",
61		msg, raw_smp_processor_id(),
62		current->comm, task_pid_nr(current));
63	printk(KERN_EMERG " lock: %pS, .magic: %08x, .owner: %s/%d, "
64			".owner_cpu: %d\n",
65		lock, READ_ONCE(lock->magic),
66		owner ? owner->comm : "<none>",
67		owner ? task_pid_nr(owner) : -1,
68		READ_ONCE(lock->owner_cpu));
69	dump_stack();
70}
71
72static void spin_bug(raw_spinlock_t *lock, const char *msg)
73{
74	if (!debug_locks_off())
75		return;
76
77	spin_dump(lock, msg);
78}
79
80#define SPIN_BUG_ON(cond, lock, msg) if (unlikely(cond)) spin_bug(lock, msg)
81
82static inline void
83debug_spin_lock_before(raw_spinlock_t *lock)
84{
85	SPIN_BUG_ON(READ_ONCE(lock->magic) != SPINLOCK_MAGIC, lock, "bad magic");
86	SPIN_BUG_ON(READ_ONCE(lock->owner) == current, lock, "recursion");
87	SPIN_BUG_ON(READ_ONCE(lock->owner_cpu) == raw_smp_processor_id(),
88							lock, "cpu recursion");
89}
90
91static inline void debug_spin_lock_after(raw_spinlock_t *lock)
92{
93	WRITE_ONCE(lock->owner_cpu, raw_smp_processor_id());
94	WRITE_ONCE(lock->owner, current);
95}
96
97static inline void debug_spin_unlock(raw_spinlock_t *lock)
98{
99	SPIN_BUG_ON(lock->magic != SPINLOCK_MAGIC, lock, "bad magic");
100	SPIN_BUG_ON(!raw_spin_is_locked(lock), lock, "already unlocked");
101	SPIN_BUG_ON(lock->owner != current, lock, "wrong owner");
102	SPIN_BUG_ON(lock->owner_cpu != raw_smp_processor_id(),
103							lock, "wrong CPU");
104	WRITE_ONCE(lock->owner, SPINLOCK_OWNER_INIT);
105	WRITE_ONCE(lock->owner_cpu, -1);
106}
107
108/*
109 * We are now relying on the NMI watchdog to detect lockup instead of doing
110 * the detection here with an unfair lock which can cause problem of its own.
111 */
112void do_raw_spin_lock(raw_spinlock_t *lock)
113{
114	debug_spin_lock_before(lock);
115	arch_spin_lock(&lock->raw_lock);
116	mmiowb_spin_lock();
117	debug_spin_lock_after(lock);
118}
119
120int do_raw_spin_trylock(raw_spinlock_t *lock)
121{
122	int ret = arch_spin_trylock(&lock->raw_lock);
123
124	if (ret) {
125		mmiowb_spin_lock();
126		debug_spin_lock_after(lock);
127	}
128#ifndef CONFIG_SMP
129	/*
130	 * Must not happen on UP:
131	 */
132	SPIN_BUG_ON(!ret, lock, "trylock failure on UP");
133#endif
134	return ret;
135}
136
137void do_raw_spin_unlock(raw_spinlock_t *lock)
138{
139	mmiowb_spin_unlock();
140	debug_spin_unlock(lock);
141	arch_spin_unlock(&lock->raw_lock);
142}
143
144#ifndef CONFIG_PREEMPT_RT
145static void rwlock_bug(rwlock_t *lock, const char *msg)
146{
147	if (!debug_locks_off())
148		return;
149
150	printk(KERN_EMERG "BUG: rwlock %s on CPU#%d, %s/%d, %p\n",
151		msg, raw_smp_processor_id(), current->comm,
152		task_pid_nr(current), lock);
153	dump_stack();
154}
155
156#define RWLOCK_BUG_ON(cond, lock, msg) if (unlikely(cond)) rwlock_bug(lock, msg)
157
158void do_raw_read_lock(rwlock_t *lock)
159{
160	RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic");
161	arch_read_lock(&lock->raw_lock);
162}
163
164int do_raw_read_trylock(rwlock_t *lock)
165{
166	int ret = arch_read_trylock(&lock->raw_lock);
167
168#ifndef CONFIG_SMP
169	/*
170	 * Must not happen on UP:
171	 */
172	RWLOCK_BUG_ON(!ret, lock, "trylock failure on UP");
173#endif
174	return ret;
175}
176
177void do_raw_read_unlock(rwlock_t *lock)
178{
179	RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic");
180	arch_read_unlock(&lock->raw_lock);
181}
182
183static inline void debug_write_lock_before(rwlock_t *lock)
184{
185	RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic");
186	RWLOCK_BUG_ON(lock->owner == current, lock, "recursion");
187	RWLOCK_BUG_ON(lock->owner_cpu == raw_smp_processor_id(),
188							lock, "cpu recursion");
189}
190
191static inline void debug_write_lock_after(rwlock_t *lock)
192{
193	WRITE_ONCE(lock->owner_cpu, raw_smp_processor_id());
194	WRITE_ONCE(lock->owner, current);
195}
196
197static inline void debug_write_unlock(rwlock_t *lock)
198{
199	RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic");
200	RWLOCK_BUG_ON(lock->owner != current, lock, "wrong owner");
201	RWLOCK_BUG_ON(lock->owner_cpu != raw_smp_processor_id(),
202							lock, "wrong CPU");
203	WRITE_ONCE(lock->owner, SPINLOCK_OWNER_INIT);
204	WRITE_ONCE(lock->owner_cpu, -1);
205}
206
207void do_raw_write_lock(rwlock_t *lock)
208{
209	debug_write_lock_before(lock);
210	arch_write_lock(&lock->raw_lock);
211	debug_write_lock_after(lock);
212}
213
214int do_raw_write_trylock(rwlock_t *lock)
215{
216	int ret = arch_write_trylock(&lock->raw_lock);
217
218	if (ret)
219		debug_write_lock_after(lock);
220#ifndef CONFIG_SMP
221	/*
222	 * Must not happen on UP:
223	 */
224	RWLOCK_BUG_ON(!ret, lock, "trylock failure on UP");
225#endif
226	return ret;
227}
228
229void do_raw_write_unlock(rwlock_t *lock)
230{
231	debug_write_unlock(lock);
232	arch_write_unlock(&lock->raw_lock);
233}
234
235#endif /* !CONFIG_PREEMPT_RT */
236