arch/s390/include/asm/spinlock.h

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