arch/s390/lib/spinlock.c

   1 /*
   2  *    Out of line spinlock code.
   3  *
   4  *    Copyright IBM Corp. 2004, 2006
   5  *    Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com)
   6  */
   7
   8 #include <linux/types.h>
   9 #include <linux/module.h>
  10 #include <linux/spinlock.h>
  11 #include <linux/init.h>
  12 #include <linux/smp.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 void arch_spin_lock_wait(arch_spinlock_t *lp)
  28 {
  29         unsigned int cpu = SPINLOCK_LOCKVAL;
  30         unsigned int owner;
  31         int count;
  32
  33         while (1) {
  34                 owner = lp->lock;
  35                 if (!owner || smp_vcpu_scheduled(~owner)) {
  36                         count = spin_retry;
  37                         do {
  38                                 if (arch_spin_is_locked(lp))
  39                                         continue;
  40                                 if (_raw_compare_and_swap(&lp->lock, 0, cpu))
  41                                         return;
  42                         } while (count-- > 0);
  43                         if (MACHINE_IS_LPAR)
  44                                 continue;
  45                 }
  46                 owner = lp->lock;
  47                 if (owner)
  48                         smp_yield_cpu(~owner);
  49                 if (_raw_compare_and_swap(&lp->lock, 0, cpu))
  50                         return;
  51         }
  52 }
  53 EXPORT_SYMBOL(arch_spin_lock_wait);
  54
  55 void arch_spin_lock_wait_flags(arch_spinlock_t *lp, unsigned long flags)
  56 {
  57         unsigned int cpu = SPINLOCK_LOCKVAL;
  58         unsigned int owner;
  59         int count;
  60
  61         local_irq_restore(flags);
  62         while (1) {
  63                 owner = lp->lock;
  64                 if (!owner || smp_vcpu_scheduled(~owner)) {
  65                         count = spin_retry;
  66                         do {
  67                                 if (arch_spin_is_locked(lp))
  68                                         continue;
  69                                 local_irq_disable();
  70                                 if (_raw_compare_and_swap(&lp->lock, 0, cpu))
  71                                         return;
  72                                 local_irq_restore(flags);
  73                         } while (count-- > 0);
  74                         if (MACHINE_IS_LPAR)
  75                                 continue;
  76                 }
  77                 owner = lp->lock;
  78                 if (owner)
  79                         smp_yield_cpu(~owner);
  80                 local_irq_disable();
  81                 if (_raw_compare_and_swap(&lp->lock, 0, cpu))
  82                         return;
  83                 local_irq_restore(flags);
  84         }
  85 }
  86 EXPORT_SYMBOL(arch_spin_lock_wait_flags);
  87
  88 void arch_spin_relax(arch_spinlock_t *lp)
  89 {
  90         unsigned int cpu = lp->lock;
  91         if (cpu != 0) {
  92                 if (MACHINE_IS_VM || MACHINE_IS_KVM ||
  93                     !smp_vcpu_scheduled(~cpu))
  94                         smp_yield_cpu(~cpu);
  95         }
  96 }
  97 EXPORT_SYMBOL(arch_spin_relax);
  98
  99 int arch_spin_trylock_retry(arch_spinlock_t *lp)
 100 {
 101         int count;
 102
 103         for (count = spin_retry; count > 0; count--)
 104                 if (arch_spin_trylock_once(lp))
 105                         return 1;
 106         return 0;
 107 }
 108 EXPORT_SYMBOL(arch_spin_trylock_retry);
 109
 110 void _raw_read_lock_wait(arch_rwlock_t *rw)
 111 {
 112         unsigned int old;
 113         int count = spin_retry;
 114
 115         while (1) {
 116                 if (count-- <= 0) {
 117                         smp_yield();
 118                         count = spin_retry;
 119                 }
 120                 old = ACCESS_ONCE(rw->lock);
 121                 if ((int) old < 0)
 122                         continue;
 123                 if (_raw_compare_and_swap(&rw->lock, old, old + 1))
 124                         return;
 125         }
 126 }
 127 EXPORT_SYMBOL(_raw_read_lock_wait);
 128
 129 void _raw_read_lock_wait_flags(arch_rwlock_t *rw, unsigned long flags)
 130 {
 131         unsigned int old;
 132         int count = spin_retry;
 133
 134         local_irq_restore(flags);
 135         while (1) {
 136                 if (count-- <= 0) {
 137                         smp_yield();
 138                         count = spin_retry;
 139                 }
 140                 old = ACCESS_ONCE(rw->lock);
 141                 if ((int) old < 0)
 142                         continue;
 143                 local_irq_disable();
 144                 if (_raw_compare_and_swap(&rw->lock, old, old + 1))
 145                         return;
 146                 local_irq_restore(flags);
 147         }
 148 }
 149 EXPORT_SYMBOL(_raw_read_lock_wait_flags);
 150
 151 int _raw_read_trylock_retry(arch_rwlock_t *rw)
 152 {
 153         unsigned int old;
 154         int count = spin_retry;
 155
 156         while (count-- > 0) {
 157                 old = ACCESS_ONCE(rw->lock);
 158                 if ((int) old < 0)
 159                         continue;
 160                 if (_raw_compare_and_swap(&rw->lock, old, old + 1))
 161                         return 1;
 162         }
 163         return 0;
 164 }
 165 EXPORT_SYMBOL(_raw_read_trylock_retry);
 166
 167 void _raw_write_lock_wait(arch_rwlock_t *rw)
 168 {
 169         unsigned int old;
 170         int count = spin_retry;
 171
 172         while (1) {
 173                 if (count-- <= 0) {
 174                         smp_yield();
 175                         count = spin_retry;
 176                 }
 177                 old = ACCESS_ONCE(rw->lock);
 178                 if (old)
 179                         continue;
 180                 if (_raw_compare_and_swap(&rw->lock, 0, 0x80000000))
 181                         return;
 182         }
 183 }
 184 EXPORT_SYMBOL(_raw_write_lock_wait);
 185
 186 void _raw_write_lock_wait_flags(arch_rwlock_t *rw, unsigned long flags)
 187 {
 188         unsigned int old;
 189         int count = spin_retry;
 190
 191         local_irq_restore(flags);
 192         while (1) {
 193                 if (count-- <= 0) {
 194                         smp_yield();
 195                         count = spin_retry;
 196                 }
 197                 old = ACCESS_ONCE(rw->lock);
 198                 if (old)
 199                         continue;
 200                 local_irq_disable();
 201                 if (_raw_compare_and_swap(&rw->lock, 0, 0x80000000))
 202                         return;
 203                 local_irq_restore(flags);
 204         }
 205 }
 206 EXPORT_SYMBOL(_raw_write_lock_wait_flags);
 207
 208 int _raw_write_trylock_retry(arch_rwlock_t *rw)
 209 {
 210         unsigned int old;
 211         int count = spin_retry;
 212
 213         while (count-- > 0) {
 214                 old = ACCESS_ONCE(rw->lock);
 215                 if (old)
 216                         continue;
 217                 if (_raw_compare_and_swap(&rw->lock, 0, 0x80000000))
 218                         return 1;
 219         }
 220         return 0;
 221 }
 222 EXPORT_SYMBOL(_raw_write_trylock_retry);