2 * include/asm-s390/spinlock.h
5 * Copyright (C) 1999 IBM Deutschland Entwicklung GmbH, IBM Corporation
6 * Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com)
8 * Derived from "include/asm-i386/spinlock.h"
11 #ifndef __ASM_SPINLOCK_H
12 #define __ASM_SPINLOCK_H
14 #include <linux/smp.h>
16 #if __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ > 2)
19 _raw_compare_and_swap(volatile unsigned int *lock,
20 unsigned int old, unsigned int new)
24 : "=d" (old), "=Q" (*lock)
25 : "0" (old), "d" (new), "Q" (*lock)
33 _raw_compare_and_swap(volatile unsigned int *lock,
34 unsigned int old, unsigned int new)
38 : "=d" (old), "=m" (*lock)
39 : "0" (old), "d" (new), "a" (lock), "m" (*lock)
47 * Simple spin lock operations. There are two variants, one clears IRQ's
48 * on the local processor, one does not.
50 * We make no fairness assumptions. They have a cost.
52 * (the type definitions are in asm/spinlock_types.h)
55 #define __raw_spin_is_locked(x) ((x)->owner_cpu != 0)
56 #define __raw_spin_lock_flags(lock, flags) __raw_spin_lock(lock)
57 #define __raw_spin_unlock_wait(lock) \
58 do { while (__raw_spin_is_locked(lock)) \
59 _raw_spin_relax(lock); } while (0)
61 extern void _raw_spin_lock_wait(raw_spinlock_t *);
62 extern int _raw_spin_trylock_retry(raw_spinlock_t *);
63 extern void _raw_spin_relax(raw_spinlock_t *lock);
65 static inline void __raw_spin_lock(raw_spinlock_t *lp)
69 old = _raw_compare_and_swap(&lp->owner_cpu, 0, ~smp_processor_id());
72 _raw_spin_lock_wait(lp);
75 static inline int __raw_spin_trylock(raw_spinlock_t *lp)
79 old = _raw_compare_and_swap(&lp->owner_cpu, 0, ~smp_processor_id());
82 return _raw_spin_trylock_retry(lp);
85 static inline void __raw_spin_unlock(raw_spinlock_t *lp)
87 _raw_compare_and_swap(&lp->owner_cpu, lp->owner_cpu, 0);
91 * Read-write spinlocks, allowing multiple readers
92 * but only one writer.
94 * NOTE! it is quite common to have readers in interrupts
95 * but no interrupt writers. For those circumstances we
96 * can "mix" irq-safe locks - any writer needs to get a
97 * irq-safe write-lock, but readers can get non-irqsafe
102 * read_can_lock - would read_trylock() succeed?
103 * @lock: the rwlock in question.
105 #define __raw_read_can_lock(x) ((int)(x)->lock >= 0)
108 * write_can_lock - would write_trylock() succeed?
109 * @lock: the rwlock in question.
111 #define __raw_write_can_lock(x) ((x)->lock == 0)
113 extern void _raw_read_lock_wait(raw_rwlock_t *lp);
114 extern int _raw_read_trylock_retry(raw_rwlock_t *lp);
115 extern void _raw_write_lock_wait(raw_rwlock_t *lp);
116 extern int _raw_write_trylock_retry(raw_rwlock_t *lp);
118 static inline void __raw_read_lock(raw_rwlock_t *rw)
121 old = rw->lock & 0x7fffffffU;
122 if (_raw_compare_and_swap(&rw->lock, old, old + 1) != old)
123 _raw_read_lock_wait(rw);
126 static inline void __raw_read_unlock(raw_rwlock_t *rw)
128 unsigned int old, cmp;
133 old = _raw_compare_and_swap(&rw->lock, old, old - 1);
134 } while (cmp != old);
137 static inline void __raw_write_lock(raw_rwlock_t *rw)
139 if (unlikely(_raw_compare_and_swap(&rw->lock, 0, 0x80000000) != 0))
140 _raw_write_lock_wait(rw);
143 static inline void __raw_write_unlock(raw_rwlock_t *rw)
145 _raw_compare_and_swap(&rw->lock, 0x80000000, 0);
148 static inline int __raw_read_trylock(raw_rwlock_t *rw)
151 old = rw->lock & 0x7fffffffU;
152 if (likely(_raw_compare_and_swap(&rw->lock, old, old + 1) == old))
154 return _raw_read_trylock_retry(rw);
157 static inline int __raw_write_trylock(raw_rwlock_t *rw)
159 if (likely(_raw_compare_and_swap(&rw->lock, 0, 0x80000000) == 0))
161 return _raw_write_trylock_retry(rw);
164 #define _raw_read_relax(lock) cpu_relax()
165 #define _raw_write_relax(lock) cpu_relax()
167 #endif /* __ASM_SPINLOCK_H */