| 1 | /* |
| 2 | * include/asm-s390/spinlock.h |
| 3 | * |
| 4 | * S390 version |
| 5 | * Copyright (C) 1999 IBM Deutschland Entwicklung GmbH, IBM Corporation |
| 6 | * Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com) |
| 7 | * |
| 8 | * Derived from "include/asm-i386/spinlock.h" |
| 9 | */ |
| 10 | |
| 11 | #ifndef __ASM_SPINLOCK_H |
| 12 | #define __ASM_SPINLOCK_H |
| 13 | |
| 14 | #include <linux/smp.h> |
| 15 | |
| 16 | #if __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ > 2) |
| 17 | |
| 18 | static inline int |
| 19 | _raw_compare_and_swap(volatile unsigned int *lock, |
| 20 | unsigned int old, unsigned int new) |
| 21 | { |
| 22 | asm volatile( |
| 23 | " cs %0,%3,%1" |
| 24 | : "=d" (old), "=Q" (*lock) |
| 25 | : "0" (old), "d" (new), "Q" (*lock) |
| 26 | : "cc", "memory" ); |
| 27 | return old; |
| 28 | } |
| 29 | |
| 30 | #else /* __GNUC__ */ |
| 31 | |
| 32 | static inline int |
| 33 | _raw_compare_and_swap(volatile unsigned int *lock, |
| 34 | unsigned int old, unsigned int new) |
| 35 | { |
| 36 | asm volatile( |
| 37 | " cs %0,%3,0(%4)" |
| 38 | : "=d" (old), "=m" (*lock) |
| 39 | : "0" (old), "d" (new), "a" (lock), "m" (*lock) |
| 40 | : "cc", "memory" ); |
| 41 | return old; |
| 42 | } |
| 43 | |
| 44 | #endif /* __GNUC__ */ |
| 45 | |
| 46 | /* |
| 47 | * Simple spin lock operations. There are two variants, one clears IRQ's |
| 48 | * on the local processor, one does not. |
| 49 | * |
| 50 | * We make no fairness assumptions. They have a cost. |
| 51 | * |
| 52 | * (the type definitions are in asm/spinlock_types.h) |
| 53 | */ |
| 54 | |
| 55 | #define __raw_spin_is_locked(x) ((x)->owner_cpu != 0) |
| 56 | #define __raw_spin_unlock_wait(lock) \ |
| 57 | do { while (__raw_spin_is_locked(lock)) \ |
| 58 | _raw_spin_relax(lock); } while (0) |
| 59 | |
| 60 | extern void _raw_spin_lock_wait(raw_spinlock_t *); |
| 61 | extern void _raw_spin_lock_wait_flags(raw_spinlock_t *, unsigned long flags); |
| 62 | extern int _raw_spin_trylock_retry(raw_spinlock_t *); |
| 63 | extern void _raw_spin_relax(raw_spinlock_t *lock); |
| 64 | |
| 65 | static inline void __raw_spin_lock(raw_spinlock_t *lp) |
| 66 | { |
| 67 | int old; |
| 68 | |
| 69 | old = _raw_compare_and_swap(&lp->owner_cpu, 0, ~smp_processor_id()); |
| 70 | if (likely(old == 0)) |
| 71 | return; |
| 72 | _raw_spin_lock_wait(lp); |
| 73 | } |
| 74 | |
| 75 | static inline void __raw_spin_lock_flags(raw_spinlock_t *lp, |
| 76 | unsigned long flags) |
| 77 | { |
| 78 | int old; |
| 79 | |
| 80 | old = _raw_compare_and_swap(&lp->owner_cpu, 0, ~smp_processor_id()); |
| 81 | if (likely(old == 0)) |
| 82 | return; |
| 83 | _raw_spin_lock_wait_flags(lp, flags); |
| 84 | } |
| 85 | |
| 86 | static inline int __raw_spin_trylock(raw_spinlock_t *lp) |
| 87 | { |
| 88 | int old; |
| 89 | |
| 90 | old = _raw_compare_and_swap(&lp->owner_cpu, 0, ~smp_processor_id()); |
| 91 | if (likely(old == 0)) |
| 92 | return 1; |
| 93 | return _raw_spin_trylock_retry(lp); |
| 94 | } |
| 95 | |
| 96 | static inline void __raw_spin_unlock(raw_spinlock_t *lp) |
| 97 | { |
| 98 | _raw_compare_and_swap(&lp->owner_cpu, lp->owner_cpu, 0); |
| 99 | } |
| 100 | |
| 101 | /* |
| 102 | * Read-write spinlocks, allowing multiple readers |
| 103 | * but only one writer. |
| 104 | * |
| 105 | * NOTE! it is quite common to have readers in interrupts |
| 106 | * but no interrupt writers. For those circumstances we |
| 107 | * can "mix" irq-safe locks - any writer needs to get a |
| 108 | * irq-safe write-lock, but readers can get non-irqsafe |
| 109 | * read-locks. |
| 110 | */ |
| 111 | |
| 112 | /** |
| 113 | * read_can_lock - would read_trylock() succeed? |
| 114 | * @lock: the rwlock in question. |
| 115 | */ |
| 116 | #define __raw_read_can_lock(x) ((int)(x)->lock >= 0) |
| 117 | |
| 118 | /** |
| 119 | * write_can_lock - would write_trylock() succeed? |
| 120 | * @lock: the rwlock in question. |
| 121 | */ |
| 122 | #define __raw_write_can_lock(x) ((x)->lock == 0) |
| 123 | |
| 124 | extern void _raw_read_lock_wait(raw_rwlock_t *lp); |
| 125 | extern void _raw_read_lock_wait_flags(raw_rwlock_t *lp, unsigned long flags); |
| 126 | extern int _raw_read_trylock_retry(raw_rwlock_t *lp); |
| 127 | extern void _raw_write_lock_wait(raw_rwlock_t *lp); |
| 128 | extern void _raw_write_lock_wait_flags(raw_rwlock_t *lp, unsigned long flags); |
| 129 | extern int _raw_write_trylock_retry(raw_rwlock_t *lp); |
| 130 | |
| 131 | static inline void __raw_read_lock(raw_rwlock_t *rw) |
| 132 | { |
| 133 | unsigned int old; |
| 134 | old = rw->lock & 0x7fffffffU; |
| 135 | if (_raw_compare_and_swap(&rw->lock, old, old + 1) != old) |
| 136 | _raw_read_lock_wait(rw); |
| 137 | } |
| 138 | |
| 139 | static inline void __raw_read_lock_flags(raw_rwlock_t *rw, unsigned long flags) |
| 140 | { |
| 141 | unsigned int old; |
| 142 | old = rw->lock & 0x7fffffffU; |
| 143 | if (_raw_compare_and_swap(&rw->lock, old, old + 1) != old) |
| 144 | _raw_read_lock_wait_flags(rw, flags); |
| 145 | } |
| 146 | |
| 147 | static inline void __raw_read_unlock(raw_rwlock_t *rw) |
| 148 | { |
| 149 | unsigned int old, cmp; |
| 150 | |
| 151 | old = rw->lock; |
| 152 | do { |
| 153 | cmp = old; |
| 154 | old = _raw_compare_and_swap(&rw->lock, old, old - 1); |
| 155 | } while (cmp != old); |
| 156 | } |
| 157 | |
| 158 | static inline void __raw_write_lock(raw_rwlock_t *rw) |
| 159 | { |
| 160 | if (unlikely(_raw_compare_and_swap(&rw->lock, 0, 0x80000000) != 0)) |
| 161 | _raw_write_lock_wait(rw); |
| 162 | } |
| 163 | |
| 164 | static inline void __raw_write_lock_flags(raw_rwlock_t *rw, unsigned long flags) |
| 165 | { |
| 166 | if (unlikely(_raw_compare_and_swap(&rw->lock, 0, 0x80000000) != 0)) |
| 167 | _raw_write_lock_wait_flags(rw, flags); |
| 168 | } |
| 169 | |
| 170 | static inline void __raw_write_unlock(raw_rwlock_t *rw) |
| 171 | { |
| 172 | _raw_compare_and_swap(&rw->lock, 0x80000000, 0); |
| 173 | } |
| 174 | |
| 175 | static inline int __raw_read_trylock(raw_rwlock_t *rw) |
| 176 | { |
| 177 | unsigned int old; |
| 178 | old = rw->lock & 0x7fffffffU; |
| 179 | if (likely(_raw_compare_and_swap(&rw->lock, old, old + 1) == old)) |
| 180 | return 1; |
| 181 | return _raw_read_trylock_retry(rw); |
| 182 | } |
| 183 | |
| 184 | static inline int __raw_write_trylock(raw_rwlock_t *rw) |
| 185 | { |
| 186 | if (likely(_raw_compare_and_swap(&rw->lock, 0, 0x80000000) == 0)) |
| 187 | return 1; |
| 188 | return _raw_write_trylock_retry(rw); |
| 189 | } |
| 190 | |
| 191 | #define _raw_read_relax(lock) cpu_relax() |
| 192 | #define _raw_write_relax(lock) cpu_relax() |
| 193 | |
| 194 | #endif /* __ASM_SPINLOCK_H */ |