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   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(arch_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(arch_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(arch_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(arch_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 void _raw_read_lock_wait_flags(raw_rwlock_t *rw, unsigned long flags)
 128 {
 129         unsigned int old;
 130         int count = spin_retry;
 131
 132         local_irq_restore(flags);
 133         while (1) {
 134                 if (count-- <= 0) {
 135                         _raw_yield();
 136                         count = spin_retry;
 137                 }
 138                 if (!__raw_read_can_lock(rw))
 139                         continue;
 140                 old = rw->lock & 0x7fffffffU;
 141                 local_irq_disable();
 142                 if (_raw_compare_and_swap(&rw->lock, old, old + 1) == old)
 143                         return;
 144         }
 145 }
 146 EXPORT_SYMBOL(_raw_read_lock_wait_flags);
 147
 148 int _raw_read_trylock_retry(raw_rwlock_t *rw)
 149 {
 150         unsigned int old;
 151         int count = spin_retry;
 152
 153         while (count-- > 0) {
 154                 if (!__raw_read_can_lock(rw))
 155                         continue;
 156                 old = rw->lock & 0x7fffffffU;
 157                 if (_raw_compare_and_swap(&rw->lock, old, old + 1) == old)
 158                         return 1;
 159         }
 160         return 0;
 161 }
 162 EXPORT_SYMBOL(_raw_read_trylock_retry);
 163
 164 void _raw_write_lock_wait(raw_rwlock_t *rw)
 165 {
 166         int count = spin_retry;
 167
 168         while (1) {
 169                 if (count-- <= 0) {
 170                         _raw_yield();
 171                         count = spin_retry;
 172                 }
 173                 if (!__raw_write_can_lock(rw))
 174                         continue;
 175                 if (_raw_compare_and_swap(&rw->lock, 0, 0x80000000) == 0)
 176                         return;
 177         }
 178 }
 179 EXPORT_SYMBOL(_raw_write_lock_wait);
 180
 181 void _raw_write_lock_wait_flags(raw_rwlock_t *rw, unsigned long flags)
 182 {
 183         int count = spin_retry;
 184
 185         local_irq_restore(flags);
 186         while (1) {
 187                 if (count-- <= 0) {
 188                         _raw_yield();
 189                         count = spin_retry;
 190                 }
 191                 if (!__raw_write_can_lock(rw))
 192                         continue;
 193                 local_irq_disable();
 194                 if (_raw_compare_and_swap(&rw->lock, 0, 0x80000000) == 0)
 195                         return;
 196         }
 197 }
 198 EXPORT_SYMBOL(_raw_write_lock_wait_flags);
 199
 200 int _raw_write_trylock_retry(raw_rwlock_t *rw)
 201 {
 202         int count = spin_retry;
 203
 204         while (count-- > 0) {
 205                 if (!__raw_write_can_lock(rw))
 206                         continue;
 207                 if (_raw_compare_and_swap(&rw->lock, 0, 0x80000000) == 0)
 208                         return 1;
 209         }
 210         return 0;
 211 }
 212 EXPORT_SYMBOL(_raw_write_trylock_retry);