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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 | |
16 | void __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 | |
32 | EXPORT_SYMBOL(__raw_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 = (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 | |
50 | EXPORT_SYMBOL(__rwlock_init); |
51 | |
52 | static 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 | |
70 | static 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 | |
80 | static inline void |
81 | debug_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 | |
89 | static 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 | |
95 | static 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 | |
106 | static 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 | |
133 | void 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 | |
141 | int 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 | |
156 | void do_raw_spin_unlock(raw_spinlock_t *lock) |
157 | { |
158 | debug_spin_unlock(lock); |
159 | arch_spin_unlock(&lock->raw_lock); |
160 | } |
161 | |
162 | static 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? */ |
176 | static 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 | |
201 | void 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 | |
207 | int 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 | |
220 | void 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 | |
226 | static 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 | |
234 | static inline void debug_write_lock_after(rwlock_t *lock) |
235 | { |
236 | lock->owner_cpu = raw_smp_processor_id(); |
237 | lock->owner = current; |
238 | } |
239 | |
240 | static 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 */ |
251 | static 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 | |
276 | void 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 | |
283 | int 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 | |
298 | void do_raw_write_unlock(rwlock_t *lock) |
299 | { |
300 | debug_write_unlock(lock); |
301 | arch_write_unlock(&lock->raw_lock); |
302 | } |
303 |
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