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brlock.c
Package: linux-2.4.20.tar.gz　[view]
Upload User: jlfgdled
Upload Date: 2013-04-10
Package Size: 33168k
Code Size: 1k
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Linux-Unix program

Development Platform:

Unix_Linux

brlock.c：Code Content
  1. /*
  2.  *
  3.  * linux/lib/brlock.c
  4.  *
  5.  * 'Big Reader' read-write spinlocks.  See linux/brlock.h for details.
  6.  *
  7.  * Copyright 2000, Ingo Molnar <mingo@redhat.com>
  8.  * Copyright 2000, David S. Miller <davem@redhat.com>
  9.  */
  11. #include <linux/config.h>
  13. #ifdef CONFIG_SMP
  15. #include <linux/sched.h>
  16. #include <linux/brlock.h>
  18. #ifdef __BRLOCK_USE_ATOMICS
  20. brlock_read_lock_t __brlock_array[NR_CPUS][__BR_IDX_MAX] =
  21.    { [0 ... NR_CPUS-1] = { [0 ... __BR_IDX_MAX-1] = RW_LOCK_UNLOCKED } };
  23. void __br_write_lock (enum brlock_indices idx)
  24. {
  25. int i;
  27. for (i = 0; i < smp_num_cpus; i++)
  28. write_lock(&__brlock_array[cpu_logical_map(i)][idx]);
  29. }
  31. void __br_write_unlock (enum brlock_indices idx)
  32. {
  33. int i;
  35. for (i = 0; i < smp_num_cpus; i++)
  36. write_unlock(&__brlock_array[cpu_logical_map(i)][idx]);
  37. }
  39. #else /* ! __BRLOCK_USE_ATOMICS */
  41. brlock_read_lock_t __brlock_array[NR_CPUS][__BR_IDX_MAX] =
  42.    { [0 ... NR_CPUS-1] = { [0 ... __BR_IDX_MAX-1] = 0 } };
  44. struct br_wrlock __br_write_locks[__BR_IDX_MAX] =
  45.    { [0 ... __BR_IDX_MAX-1] = { SPIN_LOCK_UNLOCKED } };
  47. void __br_write_lock (enum brlock_indices idx)
  48. {
  49. int i;
  51. again:
  52. spin_lock(&__br_write_locks[idx].lock);
  53. for (i = 0; i < smp_num_cpus; i++)
  54. if (__brlock_array[cpu_logical_map(i)][idx] != 0) {
  55. spin_unlock(&__br_write_locks[idx].lock);
  56. barrier();
  57. cpu_relax();
  58. goto again;
  59. }
  60. }
  62. void __br_write_unlock (enum brlock_indices idx)
  63. {
  64. spin_unlock(&__br_write_locks[idx].lock);
  65. }
  67. #endif /* __BRLOCK_USE_ATOMICS */
  69. #endif /* CONFIG_SMP */