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 void _raw_spin_lock_wait_flags(raw_spinlock_t *lp, unsigned long flags)
  63 {
  64         int count = spin_retry;
  65         unsigned int cpu = ~smp_processor_id();
  66
  67         local_irq_restore(flags);
  68         while (1) {
  69                 if (count-- <= 0) {
  70                         unsigned int owner = lp->owner_cpu;
  71                         if (owner != 0)
  72                                 _raw_yield_cpu(~owner);
  73                         count = spin_retry;
  74                 }
  75                 if (__raw_spin_is_locked(lp))
  76                         continue;
  77                 local_irq_disable();
  78                 if (_raw_compare_and_swap(&lp->owner_cpu, 0, cpu) == 0)
  79                         return;
  80                 local_irq_restore(flags);
  81         }
  82 }
  83 EXPORT_SYMBOL(_raw_spin_lock_wait_flags);
  84
  85 int _raw_spin_trylock_retry(raw_spinlock_t *lp)
  86 {
  87         unsigned int cpu = ~smp_processor_id();
  88         int count;
  89
  90         for (count = spin_retry; count > 0; count--) {
  91                 if (__raw_spin_is_locked(lp))
  92                         continue;
  93                 if (_raw_compare_and_swap(&lp->owner_cpu, 0, cpu) == 0)
  94                         return 1;
  95         }
  96         return 0;
  97 }
  98 EXPORT_SYMBOL(_raw_spin_trylock_retry);
  99
 100 void _raw_spin_relax(raw_spinlock_t *lock)
 101 {
 102         unsigned int cpu = lock->owner_cpu;
 103         if (cpu != 0)
 104                 _raw_yield_cpu(~cpu);
 105 }
 106 EXPORT_SYMBOL(_raw_spin_relax);
 107
 108 void _raw_read_lock_wait(raw_rwlock_t *rw)
 109 {
 110         unsigned int old;
 111         int count = spin_retry;
 112
 113         while (1) {
 114                 if (count-- <= 0) {
 115                         _raw_yield();
 116                         count = spin_retry;
 117                 }
 118                 if (!__raw_read_can_lock(rw))
 119                         continue;
 120                 old = rw->lock & 0x7fffffffU;
 121                 if (_raw_compare_and_swap(&rw->lock, old, old + 1) == old)
 122                         return;
 123         }
 124 }
 125 EXPORT_SYMBOL(_raw_read_lock_wait);
 126
 127 int _raw_read_trylock_retry(raw_rwlock_t *rw)
 128 {
 129         unsigned int old;
 130         int count = spin_retry;
 131
 132         while (count-- > 0) {
 133                 if (!__raw_read_can_lock(rw))
 134                         continue;
 135                 old = rw->lock & 0x7fffffffU;
 136                 if (_raw_compare_and_swap(&rw->lock, old, old + 1) == old)
 137                         return 1;
 138         }
 139         return 0;
 140 }
 141 EXPORT_SYMBOL(_raw_read_trylock_retry);
 142
 143 void _raw_write_lock_wait(raw_rwlock_t *rw)
 144 {
 145         int count = spin_retry;
 146
 147         while (1) {
 148                 if (count-- <= 0) {
 149                         _raw_yield();
 150                         count = spin_retry;
 151                 }
 152                 if (!__raw_write_can_lock(rw))
 153                         continue;
 154                 if (_raw_compare_and_swap(&rw->lock, 0, 0x80000000) == 0)
 155                         return;
 156         }
 157 }
 158 EXPORT_SYMBOL(_raw_write_lock_wait);
 159
 160 int _raw_write_trylock_retry(raw_rwlock_t *rw)
 161 {
 162         int count = spin_retry;
 163
 164         while (count-- > 0) {
 165                 if (!__raw_write_can_lock(rw))
 166                         continue;
 167                 if (_raw_compare_and_swap(&rw->lock, 0, 0x80000000) == 0)
 168                         return 1;
 169         }
 170         return 0;
 171 }
 172 EXPORT_SYMBOL(_raw_write_trylock_retry);