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, unsigned int pc)
  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                         lp->owner_pc = pc;
  58                         return;
  59                 }
  60         }
  61 }
  62 EXPORT_SYMBOL(_raw_spin_lock_wait);
  63
  64 int _raw_spin_trylock_retry(raw_spinlock_t *lp, unsigned int pc)
  65 {
  66         unsigned int cpu = ~smp_processor_id();
  67         int count;
  68
  69         for (count = spin_retry; count > 0; count--) {
  70                 if (__raw_spin_is_locked(lp))
  71                         continue;
  72                 if (_raw_compare_and_swap(&lp->owner_cpu, 0, cpu) == 0) {
  73                         lp->owner_pc = pc;
  74                         return 1;
  75                 }
  76         }
  77         return 0;
  78 }
  79 EXPORT_SYMBOL(_raw_spin_trylock_retry);
  80
  81 void _raw_spin_relax(raw_spinlock_t *lock)
  82 {
  83         unsigned int cpu = lock->owner_cpu;
  84         if (cpu != 0)
  85                 _raw_yield_cpu(~cpu);
  86 }
  87 EXPORT_SYMBOL(_raw_spin_relax);
  88
  89 void _raw_read_lock_wait(raw_rwlock_t *rw)
  90 {
  91         unsigned int old;
  92         int count = spin_retry;
  93
  94         while (1) {
  95                 if (count-- <= 0) {
  96                         _raw_yield();
  97                         count = spin_retry;
  98                 }
  99                 if (!__raw_read_can_lock(rw))
 100                         continue;
 101                 old = rw->lock & 0x7fffffffU;
 102                 if (_raw_compare_and_swap(&rw->lock, old, old + 1) == old)
 103                         return;
 104         }
 105 }
 106 EXPORT_SYMBOL(_raw_read_lock_wait);
 107
 108 int _raw_read_trylock_retry(raw_rwlock_t *rw)
 109 {
 110         unsigned int old;
 111         int count = spin_retry;
 112
 113         while (count-- > 0) {
 114                 if (!__raw_read_can_lock(rw))
 115                         continue;
 116                 old = rw->lock & 0x7fffffffU;
 117                 if (_raw_compare_and_swap(&rw->lock, old, old + 1) == old)
 118                         return 1;
 119         }
 120         return 0;
 121 }
 122 EXPORT_SYMBOL(_raw_read_trylock_retry);
 123
 124 void _raw_write_lock_wait(raw_rwlock_t *rw)
 125 {
 126         int count = spin_retry;
 127
 128         while (1) {
 129                 if (count-- <= 0) {
 130                         _raw_yield();
 131                         count = spin_retry;
 132                 }
 133                 if (!__raw_write_can_lock(rw))
 134                         continue;
 135                 if (_raw_compare_and_swap(&rw->lock, 0, 0x80000000) == 0)
 136                         return;
 137         }
 138 }
 139 EXPORT_SYMBOL(_raw_write_lock_wait);
 140
 141 int _raw_write_trylock_retry(raw_rwlock_t *rw)
 142 {
 143         int count = spin_retry;
 144
 145         while (count-- > 0) {
 146                 if (!__raw_write_can_lock(rw))
 147                         continue;
 148                 if (_raw_compare_and_swap(&rw->lock, 0, 0x80000000) == 0)
 149                         return 1;
 150         }
 151         return 0;
 152 }
 153 EXPORT_SYMBOL(_raw_write_trylock_retry);