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33#include <linux/types.h>
34#include <linux/kernel.h>
35#include <linux/init.h>
36#include <linux/spinlock.h>
37#include <linux/smp.h>
38#include <linux/interrupt.h>
39#include <linux/sched.h>
40#include <linux/atomic.h>
41#include <linux/bitops.h>
42#include <linux/percpu.h>
43#include <linux/notifier.h>
44#include <linux/cpu.h>
45#include <linux/mutex.h>
46#include <linux/export.h>
47#include <linux/hardirq.h>
48#include <linux/delay.h>
49#include <linux/module.h>
50
51#define CREATE_TRACE_POINTS
52#include <trace/events/rcu.h>
53
54#include "rcu.h"
55
56module_param(rcu_expedited, int, 0);
57
58#ifdef CONFIG_PREEMPT_RCU
59
60
61
62
63
64
65void __rcu_read_lock(void)
66{
67 current->rcu_read_lock_nesting++;
68 barrier();
69}
70EXPORT_SYMBOL_GPL(__rcu_read_lock);
71
72
73
74
75
76
77
78
79void __rcu_read_unlock(void)
80{
81 struct task_struct *t = current;
82
83 if (t->rcu_read_lock_nesting != 1) {
84 --t->rcu_read_lock_nesting;
85 } else {
86 barrier();
87 t->rcu_read_lock_nesting = INT_MIN;
88#ifdef CONFIG_PROVE_RCU_DELAY
89 udelay(10);
90#endif
91 barrier();
92 if (unlikely(ACCESS_ONCE(t->rcu_read_unlock_special)))
93 rcu_read_unlock_special(t);
94 barrier();
95 t->rcu_read_lock_nesting = 0;
96 }
97#ifdef CONFIG_PROVE_LOCKING
98 {
99 int rrln = ACCESS_ONCE(t->rcu_read_lock_nesting);
100
101 WARN_ON_ONCE(rrln < 0 && rrln > INT_MIN / 2);
102 }
103#endif
104}
105EXPORT_SYMBOL_GPL(__rcu_read_unlock);
106
107#endif
108
109#ifdef CONFIG_DEBUG_LOCK_ALLOC
110static struct lock_class_key rcu_lock_key;
111struct lockdep_map rcu_lock_map =
112 STATIC_LOCKDEP_MAP_INIT("rcu_read_lock", &rcu_lock_key);
113EXPORT_SYMBOL_GPL(rcu_lock_map);
114
115static struct lock_class_key rcu_bh_lock_key;
116struct lockdep_map rcu_bh_lock_map =
117 STATIC_LOCKDEP_MAP_INIT("rcu_read_lock_bh", &rcu_bh_lock_key);
118EXPORT_SYMBOL_GPL(rcu_bh_lock_map);
119
120static struct lock_class_key rcu_sched_lock_key;
121struct lockdep_map rcu_sched_lock_map =
122 STATIC_LOCKDEP_MAP_INIT("rcu_read_lock_sched", &rcu_sched_lock_key);
123EXPORT_SYMBOL_GPL(rcu_sched_lock_map);
124
125int debug_lockdep_rcu_enabled(void)
126{
127 return rcu_scheduler_active && debug_locks &&
128 current->lockdep_recursion == 0;
129}
130EXPORT_SYMBOL_GPL(debug_lockdep_rcu_enabled);
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147int rcu_read_lock_bh_held(void)
148{
149 if (!debug_lockdep_rcu_enabled())
150 return 1;
151 if (rcu_is_cpu_idle())
152 return 0;
153 if (!rcu_lockdep_current_cpu_online())
154 return 0;
155 return in_softirq() || irqs_disabled();
156}
157EXPORT_SYMBOL_GPL(rcu_read_lock_bh_held);
158
159#endif
160
161struct rcu_synchronize {
162 struct rcu_head head;
163 struct completion completion;
164};
165
166
167
168
169
170static void wakeme_after_rcu(struct rcu_head *head)
171{
172 struct rcu_synchronize *rcu;
173
174 rcu = container_of(head, struct rcu_synchronize, head);
175 complete(&rcu->completion);
176}
177
178void wait_rcu_gp(call_rcu_func_t crf)
179{
180 struct rcu_synchronize rcu;
181
182 init_rcu_head_on_stack(&rcu.head);
183 init_completion(&rcu.completion);
184
185 crf(&rcu.head, wakeme_after_rcu);
186
187 wait_for_completion(&rcu.completion);
188 destroy_rcu_head_on_stack(&rcu.head);
189}
190EXPORT_SYMBOL_GPL(wait_rcu_gp);
191
192#ifdef CONFIG_PROVE_RCU
193
194
195
196int rcu_my_thread_group_empty(void)
197{
198 return thread_group_empty(current);
199}
200EXPORT_SYMBOL_GPL(rcu_my_thread_group_empty);
201#endif
202
203#ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
204static inline void debug_init_rcu_head(struct rcu_head *head)
205{
206 debug_object_init(head, &rcuhead_debug_descr);
207}
208
209static inline void debug_rcu_head_free(struct rcu_head *head)
210{
211 debug_object_free(head, &rcuhead_debug_descr);
212}
213
214
215
216
217
218static int rcuhead_fixup_init(void *addr, enum debug_obj_state state)
219{
220 struct rcu_head *head = addr;
221
222 switch (state) {
223 case ODEBUG_STATE_ACTIVE:
224
225
226
227
228
229
230
231
232#ifndef CONFIG_PREEMPT
233 WARN_ON_ONCE(1);
234 return 0;
235#endif
236 if (rcu_preempt_depth() != 0 || preempt_count() != 0 ||
237 irqs_disabled()) {
238 WARN_ON_ONCE(1);
239 return 0;
240 }
241 rcu_barrier();
242 rcu_barrier_sched();
243 rcu_barrier_bh();
244 debug_object_init(head, &rcuhead_debug_descr);
245 return 1;
246 default:
247 return 0;
248 }
249}
250
251
252
253
254
255
256
257static int rcuhead_fixup_activate(void *addr, enum debug_obj_state state)
258{
259 struct rcu_head *head = addr;
260
261 switch (state) {
262
263 case ODEBUG_STATE_NOTAVAILABLE:
264
265
266
267
268 debug_object_init(head, &rcuhead_debug_descr);
269 debug_object_activate(head, &rcuhead_debug_descr);
270 return 0;
271
272 case ODEBUG_STATE_ACTIVE:
273
274
275
276
277
278
279
280
281#ifndef CONFIG_PREEMPT
282 WARN_ON_ONCE(1);
283 return 0;
284#endif
285 if (rcu_preempt_depth() != 0 || preempt_count() != 0 ||
286 irqs_disabled()) {
287 WARN_ON_ONCE(1);
288 return 0;
289 }
290 rcu_barrier();
291 rcu_barrier_sched();
292 rcu_barrier_bh();
293 debug_object_activate(head, &rcuhead_debug_descr);
294 return 1;
295 default:
296 return 0;
297 }
298}
299
300
301
302
303
304static int rcuhead_fixup_free(void *addr, enum debug_obj_state state)
305{
306 struct rcu_head *head = addr;
307
308 switch (state) {
309 case ODEBUG_STATE_ACTIVE:
310
311
312
313
314
315
316
317
318#ifndef CONFIG_PREEMPT
319 WARN_ON_ONCE(1);
320 return 0;
321#endif
322 if (rcu_preempt_depth() != 0 || preempt_count() != 0 ||
323 irqs_disabled()) {
324 WARN_ON_ONCE(1);
325 return 0;
326 }
327 rcu_barrier();
328 rcu_barrier_sched();
329 rcu_barrier_bh();
330 debug_object_free(head, &rcuhead_debug_descr);
331 return 1;
332 default:
333 return 0;
334 }
335}
336
337
338
339
340
341
342
343
344
345
346
347void init_rcu_head_on_stack(struct rcu_head *head)
348{
349 debug_object_init_on_stack(head, &rcuhead_debug_descr);
350}
351EXPORT_SYMBOL_GPL(init_rcu_head_on_stack);
352
353
354
355
356
357
358
359
360
361
362
363
364void destroy_rcu_head_on_stack(struct rcu_head *head)
365{
366 debug_object_free(head, &rcuhead_debug_descr);
367}
368EXPORT_SYMBOL_GPL(destroy_rcu_head_on_stack);
369
370struct debug_obj_descr rcuhead_debug_descr = {
371 .name = "rcu_head",
372 .fixup_init = rcuhead_fixup_init,
373 .fixup_activate = rcuhead_fixup_activate,
374 .fixup_free = rcuhead_fixup_free,
375};
376EXPORT_SYMBOL_GPL(rcuhead_debug_descr);
377#endif
378
379#if defined(CONFIG_TREE_RCU) || defined(CONFIG_TREE_PREEMPT_RCU) || defined(CONFIG_RCU_TRACE)
380void do_trace_rcu_torture_read(char *rcutorturename, struct rcu_head *rhp,
381 unsigned long secs,
382 unsigned long c_old, unsigned long c)
383{
384 trace_rcu_torture_read(rcutorturename, rhp, secs, c_old, c);
385}
386EXPORT_SYMBOL_GPL(do_trace_rcu_torture_read);
387#else
388#define do_trace_rcu_torture_read(rcutorturename, rhp, secs, c_old, c) \
389 do { } while (0)
390#endif
391
392#ifdef CONFIG_RCU_STALL_COMMON
393
394#ifdef CONFIG_PROVE_RCU
395#define RCU_STALL_DELAY_DELTA (5 * HZ)
396#else
397#define RCU_STALL_DELAY_DELTA 0
398#endif
399
400int rcu_cpu_stall_suppress __read_mostly;
401int rcu_cpu_stall_timeout __read_mostly = CONFIG_RCU_CPU_STALL_TIMEOUT;
402
403module_param(rcu_cpu_stall_suppress, int, 0644);
404module_param(rcu_cpu_stall_timeout, int, 0644);
405
406int rcu_jiffies_till_stall_check(void)
407{
408 int till_stall_check = ACCESS_ONCE(rcu_cpu_stall_timeout);
409
410
411
412
413
414 if (till_stall_check < 3) {
415 ACCESS_ONCE(rcu_cpu_stall_timeout) = 3;
416 till_stall_check = 3;
417 } else if (till_stall_check > 300) {
418 ACCESS_ONCE(rcu_cpu_stall_timeout) = 300;
419 till_stall_check = 300;
420 }
421 return till_stall_check * HZ + RCU_STALL_DELAY_DELTA;
422}
423
424static int rcu_panic(struct notifier_block *this, unsigned long ev, void *ptr)
425{
426 rcu_cpu_stall_suppress = 1;
427 return NOTIFY_DONE;
428}
429
430static struct notifier_block rcu_panic_block = {
431 .notifier_call = rcu_panic,
432};
433
434static int __init check_cpu_stall_init(void)
435{
436 atomic_notifier_chain_register(&panic_notifier_list, &rcu_panic_block);
437 return 0;
438}
439early_initcall(check_cpu_stall_init);
440
441#endif
442