3 * Copyright IBM Corp. 1999
4 * Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com)
6 * Derived from "include/asm-i386/spinlock.h"
9 #ifndef __ASM_SPINLOCK_H
10 #define __ASM_SPINLOCK_H
12 #include <linux/smp.h>
14 #define SPINLOCK_LOCKVAL (S390_lowcore.spinlock_lockval)
16 extern int spin_retry;
19 _raw_compare_and_swap(unsigned int *lock, unsigned int old, unsigned int new)
21 unsigned int old_expected = old;
25 : "=d" (old), "=Q" (*lock)
26 : "0" (old), "d" (new), "Q" (*lock)
28 return old == old_expected;
32 * Simple spin lock operations. There are two variants, one clears IRQ's
33 * on the local processor, one does not.
35 * We make no fairness assumptions. They have a cost.
37 * (the type definitions are in asm/spinlock_types.h)
40 void arch_spin_lock_wait(arch_spinlock_t *);
41 int arch_spin_trylock_retry(arch_spinlock_t *);
42 void arch_spin_relax(arch_spinlock_t *);
43 void arch_spin_lock_wait_flags(arch_spinlock_t *, unsigned long flags);
45 static inline u32 arch_spin_lockval(int cpu)
50 static inline int arch_spin_value_unlocked(arch_spinlock_t lock)
52 return lock.lock == 0;
55 static inline int arch_spin_is_locked(arch_spinlock_t *lp)
57 return ACCESS_ONCE(lp->lock) != 0;
60 static inline int arch_spin_trylock_once(arch_spinlock_t *lp)
63 return likely(arch_spin_value_unlocked(*lp) &&
64 _raw_compare_and_swap(&lp->lock, 0, SPINLOCK_LOCKVAL));
67 static inline int arch_spin_tryrelease_once(arch_spinlock_t *lp)
69 return _raw_compare_and_swap(&lp->lock, SPINLOCK_LOCKVAL, 0);
72 static inline void arch_spin_lock(arch_spinlock_t *lp)
74 if (!arch_spin_trylock_once(lp))
75 arch_spin_lock_wait(lp);
78 static inline void arch_spin_lock_flags(arch_spinlock_t *lp,
81 if (!arch_spin_trylock_once(lp))
82 arch_spin_lock_wait_flags(lp, flags);
85 static inline int arch_spin_trylock(arch_spinlock_t *lp)
87 if (!arch_spin_trylock_once(lp))
88 return arch_spin_trylock_retry(lp);
92 static inline void arch_spin_unlock(arch_spinlock_t *lp)
94 arch_spin_tryrelease_once(lp);
97 static inline void arch_spin_unlock_wait(arch_spinlock_t *lock)
99 while (arch_spin_is_locked(lock))
100 arch_spin_relax(lock);
104 * Read-write spinlocks, allowing multiple readers
105 * but only one writer.
107 * NOTE! it is quite common to have readers in interrupts
108 * but no interrupt writers. For those circumstances we
109 * can "mix" irq-safe locks - any writer needs to get a
110 * irq-safe write-lock, but readers can get non-irqsafe
115 * read_can_lock - would read_trylock() succeed?
116 * @lock: the rwlock in question.
118 #define arch_read_can_lock(x) ((int)(x)->lock >= 0)
121 * write_can_lock - would write_trylock() succeed?
122 * @lock: the rwlock in question.
124 #define arch_write_can_lock(x) ((x)->lock == 0)
126 extern void _raw_read_lock_wait(arch_rwlock_t *lp);
127 extern void _raw_read_lock_wait_flags(arch_rwlock_t *lp, unsigned long flags);
128 extern int _raw_read_trylock_retry(arch_rwlock_t *lp);
129 extern void _raw_write_lock_wait(arch_rwlock_t *lp);
130 extern void _raw_write_lock_wait_flags(arch_rwlock_t *lp, unsigned long flags);
131 extern int _raw_write_trylock_retry(arch_rwlock_t *lp);
133 static inline int arch_read_trylock_once(arch_rwlock_t *rw)
135 unsigned int old = ACCESS_ONCE(rw->lock);
136 return likely((int) old >= 0 &&
137 _raw_compare_and_swap(&rw->lock, old, old + 1));
140 static inline int arch_write_trylock_once(arch_rwlock_t *rw)
142 unsigned int old = ACCESS_ONCE(rw->lock);
143 return likely(old == 0 &&
144 _raw_compare_and_swap(&rw->lock, 0, 0x80000000));
147 static inline void arch_read_lock(arch_rwlock_t *rw)
149 if (!arch_read_trylock_once(rw))
150 _raw_read_lock_wait(rw);
153 static inline void arch_read_lock_flags(arch_rwlock_t *rw, unsigned long flags)
155 if (!arch_read_trylock_once(rw))
156 _raw_read_lock_wait_flags(rw, flags);
159 static inline void arch_read_unlock(arch_rwlock_t *rw)
164 old = ACCESS_ONCE(rw->lock);
165 } while (!_raw_compare_and_swap(&rw->lock, old, old - 1));
168 static inline void arch_write_lock(arch_rwlock_t *rw)
170 if (!arch_write_trylock_once(rw))
171 _raw_write_lock_wait(rw);
174 static inline void arch_write_lock_flags(arch_rwlock_t *rw, unsigned long flags)
176 if (!arch_write_trylock_once(rw))
177 _raw_write_lock_wait_flags(rw, flags);
180 static inline void arch_write_unlock(arch_rwlock_t *rw)
182 _raw_compare_and_swap(&rw->lock, 0x80000000, 0);
185 static inline int arch_read_trylock(arch_rwlock_t *rw)
187 if (!arch_read_trylock_once(rw))
188 return _raw_read_trylock_retry(rw);
192 static inline int arch_write_trylock(arch_rwlock_t *rw)
194 if (!arch_write_trylock_once(rw))
195 return _raw_write_trylock_retry(rw);
199 #define arch_read_relax(lock) cpu_relax()
200 #define arch_write_relax(lock) cpu_relax()
202 #endif /* __ASM_SPINLOCK_H */