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)
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(&lock->dep_map, name, key, 0);
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
34void __rwlock_init(rwlock_t *lock, const char *name,
35		   struct lock_class_key *key)
36{
37#ifdef CONFIG_DEBUG_LOCK_ALLOC
38	/*
39	 * Make sure we are not reinitializing a held lock:
40	 */
41	debug_check_no_locks_freed((void *)lock, sizeof(*lock));
42	lockdep_init_map(&lock->dep_map, name, key, 0);
43#endif
44	lock->raw_lock = (arch_rwlock_t) __ARCH_RW_LOCK_UNLOCKED;
45	lock->magic = RWLOCK_MAGIC;
46	lock->owner = SPINLOCK_OWNER_INIT;
47	lock->owner_cpu = -1;
48}
49
50EXPORT_SYMBOL(__rwlock_init);
51
52static void spin_dump(raw_spinlock_t *lock, const char *msg)
53{
54	struct task_struct *owner = NULL;
55
56	if (lock->owner && lock->owner != SPINLOCK_OWNER_INIT)
57		owner = lock->owner;
58	printk(KERN_EMERG "BUG: spinlock %s on CPU#%d, %s/%d\n",
59		msg, raw_smp_processor_id(),
60		current->comm, task_pid_nr(current));
61	printk(KERN_EMERG " lock: %pS, .magic: %08x, .owner: %s/%d, "
62			".owner_cpu: %d\n",
63		lock, lock->magic,
64		owner ? owner->comm : "<none>",
65		owner ? task_pid_nr(owner) : -1,
66		lock->owner_cpu);
67	dump_stack();
68}
69
70static void spin_bug(raw_spinlock_t *lock, const char *msg)
71{
72	if (!debug_locks_off())
73		return;
74
75	spin_dump(lock, msg);
76}
77
78#define SPIN_BUG_ON(cond, lock, msg) if (unlikely(cond)) spin_bug(lock, msg)
79
80static inline void
81debug_spin_lock_before(raw_spinlock_t *lock)
82{
83	SPIN_BUG_ON(lock->magic != SPINLOCK_MAGIC, lock, "bad magic");
84	SPIN_BUG_ON(lock->owner == current, lock, "recursion");
85	SPIN_BUG_ON(lock->owner_cpu == raw_smp_processor_id(),
86							lock, "cpu recursion");
87}
88
89static inline void debug_spin_lock_after(raw_spinlock_t *lock)
90{
91	lock->owner_cpu = raw_smp_processor_id();
92	lock->owner = current;
93}
94
95static inline void debug_spin_unlock(raw_spinlock_t *lock)
96{
97	SPIN_BUG_ON(lock->magic != SPINLOCK_MAGIC, lock, "bad magic");
98	SPIN_BUG_ON(!raw_spin_is_locked(lock), lock, "already unlocked");
99	SPIN_BUG_ON(lock->owner != current, lock, "wrong owner");
100	SPIN_BUG_ON(lock->owner_cpu != raw_smp_processor_id(),
101							lock, "wrong CPU");
102	lock->owner = SPINLOCK_OWNER_INIT;
103	lock->owner_cpu = -1;
104}
105
106static void __spin_lock_debug(raw_spinlock_t *lock)
107{
108	u64 i;
109	u64 loops = loops_per_jiffy * HZ;
110
111	for (i = 0; i < loops; i++) {
112		if (arch_spin_trylock(&lock->raw_lock))
113			return;
114		__delay(1);
115	}
116	/* lockup suspected: */
117	spin_dump(lock, "lockup suspected");
118#ifdef CONFIG_SMP
119	trigger_all_cpu_backtrace();
120#endif
121
122	/*
123	 * The trylock above was causing a livelock.  Give the lower level arch
124	 * specific lock code a chance to acquire the lock. We have already
125	 * printed a warning/backtrace at this point. The non-debug arch
126	 * specific code might actually succeed in acquiring the lock.  If it is
127	 * not successful, the end-result is the same - there is no forward
128	 * progress.
129	 */
130	arch_spin_lock(&lock->raw_lock);
131}
132
133void do_raw_spin_lock(raw_spinlock_t *lock)
134{
135	debug_spin_lock_before(lock);
136	if (unlikely(!arch_spin_trylock(&lock->raw_lock)))
137		__spin_lock_debug(lock);
138	debug_spin_lock_after(lock);
139}
140
141int do_raw_spin_trylock(raw_spinlock_t *lock)
142{
143	int ret = arch_spin_trylock(&lock->raw_lock);
144
145	if (ret)
146		debug_spin_lock_after(lock);
147#ifndef CONFIG_SMP
148	/*
149	 * Must not happen on UP:
150	 */
151	SPIN_BUG_ON(!ret, lock, "trylock failure on UP");
152#endif
153	return ret;
154}
155
156void do_raw_spin_unlock(raw_spinlock_t *lock)
157{
158	debug_spin_unlock(lock);
159	arch_spin_unlock(&lock->raw_lock);
160}
161
162static void rwlock_bug(rwlock_t *lock, const char *msg)
163{
164	if (!debug_locks_off())
165		return;
166
167	printk(KERN_EMERG "BUG: rwlock %s on CPU#%d, %s/%d, %p\n",
168		msg, raw_smp_processor_id(), current->comm,
169		task_pid_nr(current), lock);
170	dump_stack();
171}
172
173#define RWLOCK_BUG_ON(cond, lock, msg) if (unlikely(cond)) rwlock_bug(lock, msg)
174
175#if 0		/* __write_lock_debug() can lock up - maybe this can too? */
176static void __read_lock_debug(rwlock_t *lock)
177{
178	u64 i;
179	u64 loops = loops_per_jiffy * HZ;
180	int print_once = 1;
181
182	for (;;) {
183		for (i = 0; i < loops; i++) {
184			if (arch_read_trylock(&lock->raw_lock))
185				return;
186			__delay(1);
187		}
188		/* lockup suspected: */
189		if (print_once) {
190			print_once = 0;
191			printk(KERN_EMERG "BUG: read-lock lockup on CPU#%d, "
192					"%s/%d, %p\n",
193				raw_smp_processor_id(), current->comm,
194				current->pid, lock);
195			dump_stack();
196		}
197	}
198}
199#endif
200
201void do_raw_read_lock(rwlock_t *lock)
202{
203	RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic");
204	arch_read_lock(&lock->raw_lock);
205}
206
207int do_raw_read_trylock(rwlock_t *lock)
208{
209	int ret = arch_read_trylock(&lock->raw_lock);
210
211#ifndef CONFIG_SMP
212	/*
213	 * Must not happen on UP:
214	 */
215	RWLOCK_BUG_ON(!ret, lock, "trylock failure on UP");
216#endif
217	return ret;
218}
219
220void do_raw_read_unlock(rwlock_t *lock)
221{
222	RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic");
223	arch_read_unlock(&lock->raw_lock);
224}
225
226static inline void debug_write_lock_before(rwlock_t *lock)
227{
228	RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic");
229	RWLOCK_BUG_ON(lock->owner == current, lock, "recursion");
230	RWLOCK_BUG_ON(lock->owner_cpu == raw_smp_processor_id(),
231							lock, "cpu recursion");
232}
233
234static inline void debug_write_lock_after(rwlock_t *lock)
235{
236	lock->owner_cpu = raw_smp_processor_id();
237	lock->owner = current;
238}
239
240static inline void debug_write_unlock(rwlock_t *lock)
241{
242	RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic");
243	RWLOCK_BUG_ON(lock->owner != current, lock, "wrong owner");
244	RWLOCK_BUG_ON(lock->owner_cpu != raw_smp_processor_id(),
245							lock, "wrong CPU");
246	lock->owner = SPINLOCK_OWNER_INIT;
247	lock->owner_cpu = -1;
248}
249
250#if 0		/* This can cause lockups */
251static void __write_lock_debug(rwlock_t *lock)
252{
253	u64 i;
254	u64 loops = loops_per_jiffy * HZ;
255	int print_once = 1;
256
257	for (;;) {
258		for (i = 0; i < loops; i++) {
259			if (arch_write_trylock(&lock->raw_lock))
260				return;
261			__delay(1);
262		}
263		/* lockup suspected: */
264		if (print_once) {
265			print_once = 0;
266			printk(KERN_EMERG "BUG: write-lock lockup on CPU#%d, "
267					"%s/%d, %p\n",
268				raw_smp_processor_id(), current->comm,
269				current->pid, lock);
270			dump_stack();
271		}
272	}
273}
274#endif
275
276void do_raw_write_lock(rwlock_t *lock)
277{
278	debug_write_lock_before(lock);
279	arch_write_lock(&lock->raw_lock);
280	debug_write_lock_after(lock);
281}
282
283int do_raw_write_trylock(rwlock_t *lock)
284{
285	int ret = arch_write_trylock(&lock->raw_lock);
286
287	if (ret)
288		debug_write_lock_after(lock);
289#ifndef CONFIG_SMP
290	/*
291	 * Must not happen on UP:
292	 */
293	RWLOCK_BUG_ON(!ret, lock, "trylock failure on UP");
294#endif
295	return ret;
296}
297
298void do_raw_write_unlock(rwlock_t *lock)
299{
300	debug_write_unlock(lock);
301	arch_write_unlock(&lock->raw_lock);
302}
303