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 int _raw_read_trylock_retry(raw_rwlock_t *lp); 126 extern void _raw_write_lock_wait(raw_rwlock_t *lp); 127 extern int _raw_write_trylock_retry(raw_rwlock_t *lp); 128 129 static inline void __raw_read_lock(raw_rwlock_t *rw) 130 { 131 unsigned int old; 132 old = rw->lock & 0x7fffffffU; 133 if (_raw_compare_and_swap(&rw->lock, old, old + 1) != old) 134 _raw_read_lock_wait(rw); 135 } 136 137 static inline void __raw_read_unlock(raw_rwlock_t *rw) 138 { 139 unsigned int old, cmp; 140 141 old = rw->lock; 142 do { 143 cmp = old; 144 old = _raw_compare_and_swap(&rw->lock, old, old - 1); 145 } while (cmp != old); 146 } 147 148 static inline void __raw_write_lock(raw_rwlock_t *rw) 149 { 150 if (unlikely(_raw_compare_and_swap(&rw->lock, 0, 0x80000000) != 0)) 151 _raw_write_lock_wait(rw); 152 } 153 154 static inline void __raw_write_unlock(raw_rwlock_t *rw) 155 { 156 _raw_compare_and_swap(&rw->lock, 0x80000000, 0); 157 } 158 159 static inline int __raw_read_trylock(raw_rwlock_t *rw) 160 { 161 unsigned int old; 162 old = rw->lock & 0x7fffffffU; 163 if (likely(_raw_compare_and_swap(&rw->lock, old, old + 1) == old)) 164 return 1; 165 return _raw_read_trylock_retry(rw); 166 } 167 168 static inline int __raw_write_trylock(raw_rwlock_t *rw) 169 { 170 if (likely(_raw_compare_and_swap(&rw->lock, 0, 0x80000000) == 0)) 171 return 1; 172 return _raw_write_trylock_retry(rw); 173 } 174 175 #define __raw_read_lock_flags(lock, flags) __raw_read_lock(lock) 176 #define __raw_write_lock_flags(lock, flags) __raw_write_lock(lock) 177 178 #define _raw_read_relax(lock) cpu_relax() 179 #define _raw_write_relax(lock) cpu_relax() 180 181 #endif /* __ASM_SPINLOCK_H */ 182