err.no Git - linux-2.6/blob - arch/s390/lib/spinlock.c

   1 /*
   2  *  arch/s390/lib/spinlock.c
   3  *    Out of line spinlock code.
   4  *
   5  *    Copyright (C) IBM Corp. 2004, 2006
   6  *    Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com)
   7  */
   8
   9 #include <linux/types.h>
  10 #include <linux/module.h>
  11 #include <linux/spinlock.h>
  12 #include <linux/init.h>
  13 #include <asm/io.h>
  14
  15 int spin_retry = 1000;
  16
  17 /**
  18  * spin_retry= parameter
  19  */
  20 static int __init spin_retry_setup(char *str)
  21 {
  22         spin_retry = simple_strtoul(str, &str, 0);
  23         return 1;
  24 }
  25 __setup("spin_retry=", spin_retry_setup);
  26
  27 static inline void _raw_yield(void)
  28 {
  29         if (MACHINE_HAS_DIAG44)
  30                 asm volatile("diag 0,0,0x44");
  31 }
  32
  33 static inline void _raw_yield_cpu(int cpu)
  34 {
  35         if (MACHINE_HAS_DIAG9C)
  36                 asm volatile("diag %0,0,0x9c"
  37                              : : "d" (__cpu_logical_map[cpu]));
  38         else
  39                 _raw_yield();
  40 }
  41
  42 void _raw_spin_lock_wait(raw_spinlock_t *lp)
  43 {
  44         int count = spin_retry;
  45         unsigned int cpu = ~smp_processor_id();
  46
  47         while (1) {
  48                 if (count-- <= 0) {
  49                         unsigned int owner = lp->owner_cpu;
  50                         if (owner != 0)
  51                                 _raw_yield_cpu(~owner);
  52                         count = spin_retry;
  53                 }
  54                 if (__raw_spin_is_locked(lp))
  55                         continue;
  56                 if (_raw_compare_and_swap(&lp->owner_cpu, 0, cpu) == 0)
  57                         return;
  58         }
  59 }
  60 EXPORT_SYMBOL(_raw_spin_lock_wait);
  61
  62 int _raw_spin_trylock_retry(raw_spinlock_t *lp)
  63 {
  64         unsigned int cpu = ~smp_processor_id();
  65         int count;
  66
  67         for (count = spin_retry; count > 0; count--) {
  68                 if (__raw_spin_is_locked(lp))
  69                         continue;
  70                 if (_raw_compare_and_swap(&lp->owner_cpu, 0, cpu) == 0)
  71                         return 1;
  72         }
  73         return 0;
  74 }
  75 EXPORT_SYMBOL(_raw_spin_trylock_retry);
  76
  77 void _raw_spin_relax(raw_spinlock_t *lock)
  78 {
  79         unsigned int cpu = lock->owner_cpu;
  80         if (cpu != 0)
  81                 _raw_yield_cpu(~cpu);
  82 }
  83 EXPORT_SYMBOL(_raw_spin_relax);
  84
  85 void _raw_read_lock_wait(raw_rwlock_t *rw)
  86 {
  87         unsigned int old;
  88         int count = spin_retry;
  89
  90         while (1) {
  91                 if (count-- <= 0) {
  92                         _raw_yield();
  93                         count = spin_retry;
  94                 }
  95                 if (!__raw_read_can_lock(rw))
  96                         continue;
  97                 old = rw->lock & 0x7fffffffU;
  98                 if (_raw_compare_and_swap(&rw->lock, old, old + 1) == old)
  99                         return;
 100         }
 101 }
 102 EXPORT_SYMBOL(_raw_read_lock_wait);
 103
 104 int _raw_read_trylock_retry(raw_rwlock_t *rw)
 105 {
 106         unsigned int old;
 107         int count = spin_retry;
 108
 109         while (count-- > 0) {
 110                 if (!__raw_read_can_lock(rw))
 111                         continue;
 112                 old = rw->lock & 0x7fffffffU;
 113                 if (_raw_compare_and_swap(&rw->lock, old, old + 1) == old)
 114                         return 1;
 115         }
 116         return 0;
 117 }
 118 EXPORT_SYMBOL(_raw_read_trylock_retry);
 119
 120 void _raw_write_lock_wait(raw_rwlock_t *rw)
 121 {
 122         int count = spin_retry;
 123
 124         while (1) {
 125                 if (count-- <= 0) {
 126                         _raw_yield();
 127                         count = spin_retry;
 128                 }
 129                 if (!__raw_write_can_lock(rw))
 130                         continue;
 131                 if (_raw_compare_and_swap(&rw->lock, 0, 0x80000000) == 0)
 132                         return;
 133         }
 134 }
 135 EXPORT_SYMBOL(_raw_write_lock_wait);
 136
 137 int _raw_write_trylock_retry(raw_rwlock_t *rw)
 138 {
 139         int count = spin_retry;
 140
 141         while (count-- > 0) {
 142                 if (!__raw_write_can_lock(rw))
 143                         continue;
 144                 if (_raw_compare_and_swap(&rw->lock, 0, 0x80000000) == 0)
 145                         return 1;
 146         }
 147         return 0;
 148 }
 149 EXPORT_SYMBOL(_raw_write_trylock_retry);