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(lock->owner == current, lock, "recursion");
188	RWLOCK_BUG_ON(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 */