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 arch_spin_lock_wait(arch_spinlock_t *lp)
  43 {
  44         int count = spin_retry;
  45         unsigned int cpu = ~smp_processor_id();
  46         unsigned int owner;
  47
  48         while (1) {
  49                 owner = lp->owner_cpu;
  50                 if (!owner || smp_vcpu_scheduled(~owner)) {
  51                         for (count = spin_retry; count > 0; count--) {
  52                                 if (arch_spin_is_locked(lp))
  53                                         continue;
  54                                 if (_raw_compare_and_swap(&lp->owner_cpu, 0,
  55                                                           cpu) == 0)
  56                                         return;
  57                         }
  58                         if (MACHINE_IS_LPAR)
  59                                 continue;
  60                 }
  61                 owner = lp->owner_cpu;
  62                 if (owner)
  63                         _raw_yield_cpu(~owner);
  64                 if (_raw_compare_and_swap(&lp->owner_cpu, 0, cpu) == 0)
  65                         return;
  66         }
  67 }
  68 EXPORT_SYMBOL(arch_spin_lock_wait);
  69
  70 void arch_spin_lock_wait_flags(arch_spinlock_t *lp, unsigned long flags)
  71 {
  72         int count = spin_retry;
  73         unsigned int cpu = ~smp_processor_id();
  74         unsigned int owner;
  75
  76         local_irq_restore(flags);
  77         while (1) {
  78                 owner = lp->owner_cpu;
  79                 if (!owner || smp_vcpu_scheduled(~owner)) {
  80                         for (count = spin_retry; count > 0; count--) {
  81                                 if (arch_spin_is_locked(lp))
  82                                         continue;
  83                                 local_irq_disable();
  84                                 if (_raw_compare_and_swap(&lp->owner_cpu, 0,
  85                                                           cpu) == 0)
  86                                         return;
  87                                 local_irq_restore(flags);
  88                         }
  89                         if (MACHINE_IS_LPAR)
  90                                 continue;
  91                 }
  92                 owner = lp->owner_cpu;
  93                 if (owner)
  94                         _raw_yield_cpu(~owner);
  95                 local_irq_disable();
  96                 if (_raw_compare_and_swap(&lp->owner_cpu, 0, cpu) == 0)
  97                         return;
  98                 local_irq_restore(flags);
  99         }
 100 }
 101 EXPORT_SYMBOL(arch_spin_lock_wait_flags);
 102
 103 int arch_spin_trylock_retry(arch_spinlock_t *lp)
 104 {
 105         unsigned int cpu = ~smp_processor_id();
 106         int count;
 107
 108         for (count = spin_retry; count > 0; count--) {
 109                 if (arch_spin_is_locked(lp))
 110                         continue;
 111                 if (_raw_compare_and_swap(&lp->owner_cpu, 0, cpu) == 0)
 112                         return 1;
 113         }
 114         return 0;
 115 }
 116 EXPORT_SYMBOL(arch_spin_trylock_retry);
 117
 118 void arch_spin_relax(arch_spinlock_t *lock)
 119 {
 120         unsigned int cpu = lock->owner_cpu;
 121         if (cpu != 0) {
 122                 if (MACHINE_IS_VM || MACHINE_IS_KVM ||
 123                     !smp_vcpu_scheduled(~cpu))
 124                         _raw_yield_cpu(~cpu);
 125         }
 126 }
 127 EXPORT_SYMBOL(arch_spin_relax);
 128
 129 void _raw_read_lock_wait(arch_rwlock_t *rw)
 130 {
 131         unsigned int old;
 132         int count = spin_retry;
 133
 134         while (1) {
 135                 if (count-- <= 0) {
 136                         _raw_yield();
 137                         count = spin_retry;
 138                 }
 139                 if (!arch_read_can_lock(rw))
 140                         continue;
 141                 old = rw->lock & 0x7fffffffU;
 142                 if (_raw_compare_and_swap(&rw->lock, old, old + 1) == old)
 143                         return;
 144         }
 145 }
 146 EXPORT_SYMBOL(_raw_read_lock_wait);
 147
 148 void _raw_read_lock_wait_flags(arch_rwlock_t *rw, unsigned long flags)
 149 {
 150         unsigned int old;
 151         int count = spin_retry;
 152
 153         local_irq_restore(flags);
 154         while (1) {
 155                 if (count-- <= 0) {
 156                         _raw_yield();
 157                         count = spin_retry;
 158                 }
 159                 if (!arch_read_can_lock(rw))
 160                         continue;
 161                 old = rw->lock & 0x7fffffffU;
 162                 local_irq_disable();
 163                 if (_raw_compare_and_swap(&rw->lock, old, old + 1) == old)
 164                         return;
 165         }
 166 }
 167 EXPORT_SYMBOL(_raw_read_lock_wait_flags);
 168
 169 int _raw_read_trylock_retry(arch_rwlock_t *rw)
 170 {
 171         unsigned int old;
 172         int count = spin_retry;
 173
 174         while (count-- > 0) {
 175                 if (!arch_read_can_lock(rw))
 176                         continue;
 177                 old = rw->lock & 0x7fffffffU;
 178                 if (_raw_compare_and_swap(&rw->lock, old, old + 1) == old)
 179                         return 1;
 180         }
 181         return 0;
 182 }
 183 EXPORT_SYMBOL(_raw_read_trylock_retry);
 184
 185 void _raw_write_lock_wait(arch_rwlock_t *rw)
 186 {
 187         int count = spin_retry;
 188
 189         while (1) {
 190                 if (count-- <= 0) {
 191                         _raw_yield();
 192                         count = spin_retry;
 193                 }
 194                 if (!arch_write_can_lock(rw))
 195                         continue;
 196                 if (_raw_compare_and_swap(&rw->lock, 0, 0x80000000) == 0)
 197                         return;
 198         }
 199 }
 200 EXPORT_SYMBOL(_raw_write_lock_wait);
 201
 202 void _raw_write_lock_wait_flags(arch_rwlock_t *rw, unsigned long flags)
 203 {
 204         int count = spin_retry;
 205
 206         local_irq_restore(flags);
 207         while (1) {
 208                 if (count-- <= 0) {
 209                         _raw_yield();
 210                         count = spin_retry;
 211                 }
 212                 if (!arch_write_can_lock(rw))
 213                         continue;
 214                 local_irq_disable();
 215                 if (_raw_compare_and_swap(&rw->lock, 0, 0x80000000) == 0)
 216                         return;
 217         }
 218 }
 219 EXPORT_SYMBOL(_raw_write_lock_wait_flags);
 220
 221 int _raw_write_trylock_retry(arch_rwlock_t *rw)
 222 {
 223         int count = spin_retry;
 224
 225         while (count-- > 0) {
 226                 if (!arch_write_can_lock(rw))
 227                         continue;
 228                 if (_raw_compare_and_swap(&rw->lock, 0, 0x80000000) == 0)
 229                         return 1;
 230         }
 231         return 0;
 232 }
 233 EXPORT_SYMBOL(_raw_write_trylock_retry);