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_is_locked(lp))
 105                         continue;
 106                 if (arch_spin_trylock_once(lp))
 107                         return 1;
 108         }
 109         return 0;
 110 }
 111 EXPORT_SYMBOL(arch_spin_trylock_retry);
 112
 113 void _raw_read_lock_wait(arch_rwlock_t *rw)
 114 {
 115         unsigned int old;
 116         int count = spin_retry;
 117
 118         while (1) {
 119                 if (count-- <= 0) {
 120                         smp_yield();
 121                         count = spin_retry;
 122                 }
 123                 if (!arch_read_can_lock(rw))
 124                         continue;
 125                 old = rw->lock & 0x7fffffffU;
 126                 if (_raw_compare_and_swap(&rw->lock, old, old + 1))
 127                         return;
 128         }
 129 }
 130 EXPORT_SYMBOL(_raw_read_lock_wait);
 131
 132 void _raw_read_lock_wait_flags(arch_rwlock_t *rw, unsigned long flags)
 133 {
 134         unsigned int old;
 135         int count = spin_retry;
 136
 137         local_irq_restore(flags);
 138         while (1) {
 139                 if (count-- <= 0) {
 140                         smp_yield();
 141                         count = spin_retry;
 142                 }
 143                 if (!arch_read_can_lock(rw))
 144                         continue;
 145                 old = rw->lock & 0x7fffffffU;
 146                 local_irq_disable();
 147                 if (_raw_compare_and_swap(&rw->lock, old, old + 1))
 148                         return;
 149         }
 150 }
 151 EXPORT_SYMBOL(_raw_read_lock_wait_flags);
 152
 153 int _raw_read_trylock_retry(arch_rwlock_t *rw)
 154 {
 155         unsigned int old;
 156         int count = spin_retry;
 157
 158         while (count-- > 0) {
 159                 if (!arch_read_can_lock(rw))
 160                         continue;
 161                 old = rw->lock & 0x7fffffffU;
 162                 if (_raw_compare_and_swap(&rw->lock, old, old + 1))
 163                         return 1;
 164         }
 165         return 0;
 166 }
 167 EXPORT_SYMBOL(_raw_read_trylock_retry);
 168
 169 void _raw_write_lock_wait(arch_rwlock_t *rw)
 170 {
 171         int count = spin_retry;
 172
 173         while (1) {
 174                 if (count-- <= 0) {
 175                         smp_yield();
 176                         count = spin_retry;
 177                 }
 178                 if (!arch_write_can_lock(rw))
 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         int count = spin_retry;
 189
 190         local_irq_restore(flags);
 191         while (1) {
 192                 if (count-- <= 0) {
 193                         smp_yield();
 194                         count = spin_retry;
 195                 }
 196                 if (!arch_write_can_lock(rw))
 197                         continue;
 198                 local_irq_disable();
 199                 if (_raw_compare_and_swap(&rw->lock, 0, 0x80000000))
 200                         return;
 201         }
 202 }
 203 EXPORT_SYMBOL(_raw_write_lock_wait_flags);
 204
 205 int _raw_write_trylock_retry(arch_rwlock_t *rw)
 206 {
 207         int count = spin_retry;
 208
 209         while (count-- > 0) {
 210                 if (!arch_write_can_lock(rw))
 211                         continue;
 212                 if (_raw_compare_and_swap(&rw->lock, 0, 0x80000000))
 213                         return 1;
 214         }
 215         return 0;
 216 }
 217 EXPORT_SYMBOL(_raw_write_trylock_retry);