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
  28 _diag44(void)
  29 {
  30 #ifdef CONFIG_64BIT
  31         if (MACHINE_HAS_DIAG44)
  32 #endif
  33                 asm volatile("diag 0,0,0x44");
  34 }
  35
  36 void
  37 _raw_spin_lock_wait(raw_spinlock_t *lp, unsigned int pc)
  38 {
  39         int count = spin_retry;
  40
  41         while (1) {
  42                 if (count-- <= 0) {
  43                         _diag44();
  44                         count = spin_retry;
  45                 }
  46                 if (__raw_spin_is_locked(lp))
  47                         continue;
  48                 if (_raw_compare_and_swap(&lp->lock, 0, pc) == 0)
  49                         return;
  50         }
  51 }
  52 EXPORT_SYMBOL(_raw_spin_lock_wait);
  53
  54 int
  55 _raw_spin_trylock_retry(raw_spinlock_t *lp, unsigned int pc)
  56 {
  57         int count = spin_retry;
  58
  59         while (count-- > 0) {
  60                 if (__raw_spin_is_locked(lp))
  61                         continue;
  62                 if (_raw_compare_and_swap(&lp->lock, 0, pc) == 0)
  63                         return 1;
  64         }
  65         return 0;
  66 }
  67 EXPORT_SYMBOL(_raw_spin_trylock_retry);
  68
  69 void
  70 _raw_read_lock_wait(raw_rwlock_t *rw)
  71 {
  72         unsigned int old;
  73         int count = spin_retry;
  74
  75         while (1) {
  76                 if (count-- <= 0) {
  77                         _diag44();
  78                         count = spin_retry;
  79                 }
  80                 if (!__raw_read_can_lock(rw))
  81                         continue;
  82                 old = rw->lock & 0x7fffffffU;
  83                 if (_raw_compare_and_swap(&rw->lock, old, old + 1) == old)
  84                         return;
  85         }
  86 }
  87 EXPORT_SYMBOL(_raw_read_lock_wait);
  88
  89 int
  90 _raw_read_trylock_retry(raw_rwlock_t *rw)
  91 {
  92         unsigned int old;
  93         int count = spin_retry;
  94
  95         while (count-- > 0) {
  96                 if (!__raw_read_can_lock(rw))
  97                         continue;
  98                 old = rw->lock & 0x7fffffffU;
  99                 if (_raw_compare_and_swap(&rw->lock, old, old + 1) == old)
 100                         return 1;
 101         }
 102         return 0;
 103 }
 104 EXPORT_SYMBOL(_raw_read_trylock_retry);
 105
 106 void
 107 _raw_write_lock_wait(raw_rwlock_t *rw)
 108 {
 109         int count = spin_retry;
 110
 111         while (1) {
 112                 if (count-- <= 0) {
 113                         _diag44();
 114                         count = spin_retry;
 115                 }
 116                 if (!__raw_write_can_lock(rw))
 117                         continue;
 118                 if (_raw_compare_and_swap(&rw->lock, 0, 0x80000000) == 0)
 119                         return;
 120         }
 121 }
 122 EXPORT_SYMBOL(_raw_write_lock_wait);
 123
 124 int
 125 _raw_write_trylock_retry(raw_rwlock_t *rw)
 126 {
 127         int count = spin_retry;
 128
 129         while (count-- > 0) {
 130                 if (!__raw_write_can_lock(rw))
 131                         continue;
 132                 if (_raw_compare_and_swap(&rw->lock, 0, 0x80000000) == 0)
 133                         return 1;
 134         }
 135         return 0;
 136 }
 137 EXPORT_SYMBOL(_raw_write_trylock_retry);