projects/linux·blob rcu-free-v3 · refs

236 lines · 5.9 KiB

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