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/module.h>
15
16 void __spin_lock_init(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 = (raw_spinlock_t)__RAW_SPIN_LOCK_UNLOCKED;
27 lock->magic = SPINLOCK_MAGIC;
28 lock->owner = SPINLOCK_OWNER_INIT;
29 lock->owner_cpu = -1;
30 }
31
32 EXPORT_SYMBOL(__spin_lock_init);
33
34 void __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 = (raw_rwlock_t) __RAW_RW_LOCK_UNLOCKED;
45 lock->magic = RWLOCK_MAGIC;
46 lock->owner = SPINLOCK_OWNER_INIT;
47 lock->owner_cpu = -1;
48 }
49
50 EXPORT_SYMBOL(__rwlock_init);
51
52 static void spin_bug(spinlock_t *lock, const char *msg)
53 {
54 struct task_struct *owner = NULL;
55
56 if (!debug_locks_off())
57 return;
58
59 if (lock->owner && lock->owner != SPINLOCK_OWNER_INIT)
60 owner = lock->owner;
61 printk(KERN_EMERG "BUG: spinlock %s on CPU#%d, %s/%d\n",
62 msg, raw_smp_processor_id(),
63 current->comm, task_pid_nr(current));
64 printk(KERN_EMERG " lock: %p, .magic: %08x, .owner: %s/%d, "
65 ".owner_cpu: %d\n",
66 lock, lock->magic,
67 owner ? owner->comm : "<none>",
68 owner ? task_pid_nr(owner) : -1,
69 lock->owner_cpu);
70 dump_stack();
71 }
72
73 #define SPIN_BUG_ON(cond, lock, msg) if (unlikely(cond)) spin_bug(lock, msg)
74
75 static inline void
76 debug_spin_lock_before(spinlock_t *lock)
77 {
78 SPIN_BUG_ON(lock->magic != SPINLOCK_MAGIC, lock, "bad magic");
79 SPIN_BUG_ON(lock->owner == current, lock, "recursion");
80 SPIN_BUG_ON(lock->owner_cpu == raw_smp_processor_id(),
81 lock, "cpu recursion");
82 }
83
84 static inline void debug_spin_lock_after(spinlock_t *lock)
85 {
86 lock->owner_cpu = raw_smp_processor_id();
87 lock->owner = current;
88 }
89
90 static inline void debug_spin_unlock(spinlock_t *lock)
91 {
92 SPIN_BUG_ON(lock->magic != SPINLOCK_MAGIC, lock, "bad magic");
93 SPIN_BUG_ON(!spin_is_locked(lock), lock, "already unlocked");
94 SPIN_BUG_ON(lock->owner != current, lock, "wrong owner");
95 SPIN_BUG_ON(lock->owner_cpu != raw_smp_processor_id(),
96 lock, "wrong CPU");
97 lock->owner = SPINLOCK_OWNER_INIT;
98 lock->owner_cpu = -1;
99 }
100
101 static void __spin_lock_debug(spinlock_t *lock)
102 {
103 u64 i;
104 u64 loops = loops_per_jiffy * HZ;
105 int print_once = 1;
106
107 for (;;) {
108 for (i = 0; i < loops; i++) {
109 if (__raw_spin_trylock(&lock->raw_lock))
110 return;
111 __delay(1);
112 }
113 /* lockup suspected: */
114 if (print_once) {
115 print_once = 0;
116 printk(KERN_EMERG "BUG: spinlock lockup on CPU#%d, "
117 "%s/%d, %p\n",
118 raw_smp_processor_id(), current->comm,
119 task_pid_nr(current), lock);
120 dump_stack();
121 #ifdef CONFIG_SMP
122 trigger_all_cpu_backtrace();
123 #endif
124 }
125 }
126 }
127
128 void _raw_spin_lock(spinlock_t *lock)
129 {
130 debug_spin_lock_before(lock);
131 if (unlikely(!__raw_spin_trylock(&lock->raw_lock)))
132 __spin_lock_debug(lock);
133 debug_spin_lock_after(lock);
134 }
135
136 int _raw_spin_trylock(spinlock_t *lock)
137 {
138 int ret = __raw_spin_trylock(&lock->raw_lock);
139
140 if (ret)
141 debug_spin_lock_after(lock);
142 #ifndef CONFIG_SMP
143 /*
144 * Must not happen on UP:
145 */
146 SPIN_BUG_ON(!ret, lock, "trylock failure on UP");
147 #endif
148 return ret;
149 }
150
151 void _raw_spin_unlock(spinlock_t *lock)
152 {
153 debug_spin_unlock(lock);
154 __raw_spin_unlock(&lock->raw_lock);
155 }
156
157 static void rwlock_bug(rwlock_t *lock, const char *msg)
158 {
159 if (!debug_locks_off())
160 return;
161
162 printk(KERN_EMERG "BUG: rwlock %s on CPU#%d, %s/%d, %p\n",
163 msg, raw_smp_processor_id(), current->comm,
164 task_pid_nr(current), lock);
165 dump_stack();
166 }
167
168 #define RWLOCK_BUG_ON(cond, lock, msg) if (unlikely(cond)) rwlock_bug(lock, msg)
169
170 #if 0 /* __write_lock_debug() can lock up - maybe this can too? */
171 static void __read_lock_debug(rwlock_t *lock)
172 {
173 u64 i;
174 u64 loops = loops_per_jiffy * HZ;
175 int print_once = 1;
176
177 for (;;) {
178 for (i = 0; i < loops; i++) {
179 if (__raw_read_trylock(&lock->raw_lock))
180 return;
181 __delay(1);
182 }
183 /* lockup suspected: */
184 if (print_once) {
185 print_once = 0;
186 printk(KERN_EMERG "BUG: read-lock lockup on CPU#%d, "
187 "%s/%d, %p\n",
188 raw_smp_processor_id(), current->comm,
189 current->pid, lock);
190 dump_stack();
191 }
192 }
193 }
194 #endif
195
196 void _raw_read_lock(rwlock_t *lock)
197 {
198 RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic");
199 __raw_read_lock(&lock->raw_lock);
200 }
201
202 int _raw_read_trylock(rwlock_t *lock)
203 {
204 int ret = __raw_read_trylock(&lock->raw_lock);
205
206 #ifndef CONFIG_SMP
207 /*
208 * Must not happen on UP:
209 */
210 RWLOCK_BUG_ON(!ret, lock, "trylock failure on UP");
211 #endif
212 return ret;
213 }
214
215 void _raw_read_unlock(rwlock_t *lock)
216 {
217 RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic");
218 __raw_read_unlock(&lock->raw_lock);
219 }
220
221 static inline void debug_write_lock_before(rwlock_t *lock)
222 {
223 RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic");
224 RWLOCK_BUG_ON(lock->owner == current, lock, "recursion");
225 RWLOCK_BUG_ON(lock->owner_cpu == raw_smp_processor_id(),
226 lock, "cpu recursion");
227 }
228
229 static inline void debug_write_lock_after(rwlock_t *lock)
230 {
231 lock->owner_cpu = raw_smp_processor_id();
232 lock->owner = current;
233 }
234
235 static inline void debug_write_unlock(rwlock_t *lock)
236 {
237 RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic");
238 RWLOCK_BUG_ON(lock->owner != current, lock, "wrong owner");
239 RWLOCK_BUG_ON(lock->owner_cpu != raw_smp_processor_id(),
240 lock, "wrong CPU");
241 lock->owner = SPINLOCK_OWNER_INIT;
242 lock->owner_cpu = -1;
243 }
244
245 #if 0 /* This can cause lockups */
246 static void __write_lock_debug(rwlock_t *lock)
247 {
248 u64 i;
249 u64 loops = loops_per_jiffy * HZ;
250 int print_once = 1;
251
252 for (;;) {
253 for (i = 0; i < loops; i++) {
254 if (__raw_write_trylock(&lock->raw_lock))
255 return;
256 __delay(1);
257 }
258 /* lockup suspected: */
259 if (print_once) {
260 print_once = 0;
261 printk(KERN_EMERG "BUG: write-lock lockup on CPU#%d, "
262 "%s/%d, %p\n",
263 raw_smp_processor_id(), current->comm,
264 current->pid, lock);
265 dump_stack();
266 }
267 }
268 }
269 #endif
270
271 void _raw_write_lock(rwlock_t *lock)
272 {
273 debug_write_lock_before(lock);
274 __raw_write_lock(&lock->raw_lock);
275 debug_write_lock_after(lock);
276 }
277
278 int _raw_write_trylock(rwlock_t *lock)
279 {
280 int ret = __raw_write_trylock(&lock->raw_lock);
281
282 if (ret)
283 debug_write_lock_after(lock);
284 #ifndef CONFIG_SMP
285 /*
286 * Must not happen on UP:
287 */
288 RWLOCK_BUG_ON(!ret, lock, "trylock failure on UP");
289 #endif
290 return ret;
291 }
292
293 void _raw_write_unlock(rwlock_t *lock)
294 {
295 debug_write_unlock(lock);
296 __raw_write_unlock(&lock->raw_lock);
297 }
298
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