arch/s390/lib/spinlock.c

   1 /*
   2  *  arch/s390/lib/spinlock.c
   3  *    Out of line spinlock code.
   4  *
   5  *  S390 version
   6  *    Copyright (C) 2004 IBM Deutschland Entwicklung GmbH, IBM Corporation
   7  *    Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com)
   8  */
   9
  10 #include <linux/types.h>
  11 #include <linux/module.h>
  12 #include <linux/spinlock.h>
  13 #include <linux/init.h>
  14 #include <asm/io.h>
  15
  16 atomic_t spin_retry_counter;
  17 int spin_retry = 1000;
  18
  19 /**
  20  * spin_retry= parameter
  21  */
  22 static int __init spin_retry_setup(char *str)
  23 {
  24         spin_retry = simple_strtoul(str, &str, 0);
  25         return 1;
  26 }
  27 __setup("spin_retry=", spin_retry_setup);
  28
  29 static inline void
  30 _diag44(void)
  31 {
  32 #ifdef __s390x__
  33         if (MACHINE_HAS_DIAG44)
  34 #endif
  35                 asm volatile("diag 0,0,0x44");
  36 }
  37
  38 void
  39 _raw_spin_lock_wait(raw_spinlock_t *lp, unsigned int pc)
  40 {
  41         int count = spin_retry;
  42
  43         while (1) {
  44                 if (count-- <= 0) {
  45                         _diag44();
  46                         count = spin_retry;
  47                 }
  48                 atomic_inc(&spin_retry_counter);
  49                 if (_raw_compare_and_swap(&lp->lock, 0, pc) == 0)
  50                         return;
  51         }
  52 }
  53 EXPORT_SYMBOL(_raw_spin_lock_wait);
  54
  55 int
  56 _raw_spin_trylock_retry(raw_spinlock_t *lp, unsigned int pc)
  57 {
  58         int count = spin_retry;
  59
  60         while (count-- > 0) {
  61                 atomic_inc(&spin_retry_counter);
  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                 atomic_inc(&spin_retry_counter);
  81                 old = rw->lock & 0x7fffffffU;
  82                 if (_raw_compare_and_swap(&rw->lock, old, old + 1) == old)
  83                         return;
  84         }
  85 }
  86 EXPORT_SYMBOL(_raw_read_lock_wait);
  87
  88 int
  89 _raw_read_trylock_retry(raw_rwlock_t *rw)
  90 {
  91         unsigned int old;
  92         int count = spin_retry;
  93
  94         while (count-- > 0) {
  95                 atomic_inc(&spin_retry_counter);
  96                 old = rw->lock & 0x7fffffffU;
  97                 if (_raw_compare_and_swap(&rw->lock, old, old + 1) == old)
  98                         return 1;
  99         }
 100         return 0;
 101 }
 102 EXPORT_SYMBOL(_raw_read_trylock_retry);
 103
 104 void
 105 _raw_write_lock_wait(raw_rwlock_t *rw)
 106 {
 107         int count = spin_retry;
 108
 109         while (1) {
 110                 if (count-- <= 0) {
 111                         _diag44();
 112                         count = spin_retry;
 113                 }
 114                 atomic_inc(&spin_retry_counter);
 115                 if (_raw_compare_and_swap(&rw->lock, 0, 0x80000000) == 0)
 116                         return;
 117         }
 118 }
 119 EXPORT_SYMBOL(_raw_write_lock_wait);
 120
 121 int
 122 _raw_write_trylock_retry(raw_rwlock_t *rw)
 123 {
 124         int count = spin_retry;
 125
 126         while (count-- > 0) {
 127                 atomic_inc(&spin_retry_counter);
 128                 if (_raw_compare_and_swap(&rw->lock, 0, 0x80000000) == 0)
 129                         return 1;
 130         }
 131         return 0;
 132 }
 133 EXPORT_SYMBOL(_raw_write_trylock_retry);