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
17 void __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
33 EXPORT_SYMBOL(__raw_spin_lock_init);
34
35 #ifndef CONFIG_PREEMPT_RT
36 void __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
52 EXPORT_SYMBOL(__rwlock_init);
53 #endif
54
55 static 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
73 static 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
83 static inline void
84 debug_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
92 static 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
98 static 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 */
113 void 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
121 int 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
138 void 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
146 static 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
159 void 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
165 int 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
178 void 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
184 static 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(lock->owner == current, lock, "recursion");
188 RWLOCK_BUG_ON(lock->owner_cpu == raw_smp_processor_id(),
189 lock, "cpu recursion");
190 }
191
192 static 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
198 static 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
208 void 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
215 int 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
230 void 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 */
237
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