/arch/ppc64/lib/locks.c

https://bitbucket.org/evzijst/gittest · C · 95 lines · 68 code · 8 blank · 19 comment · 14 complexity · c8b2f678b680f784ec52ed60545a8a77 MD5 · raw file 

    

  1. /*
    2. 

  2.  * Spin and read/write lock operations.
    3. 

  3.  *
    4. 

  4.  * Copyright (C) 2001-2004 Paul Mackerras <paulus@au.ibm.com>, IBM
    5. 

  5.  * Copyright (C) 2001 Anton Blanchard <anton@au.ibm.com>, IBM
    6. 

  6.  * Copyright (C) 2002 Dave Engebretsen <engebret@us.ibm.com>, IBM
    7. 

  7.  *   Rework to support virtual processors
    8. 

  8.  *
    9. 

  9.  * This program is free software; you can redistribute it and/or
    10. 

  10.  * modify it under the terms of the GNU General Public License
    11. 

  11.  * as published by the Free Software Foundation; either version
    12. 

  12.  * 2 of the License, or (at your option) any later version.
    13. 

  13.  */
    14. 

  14. 

  15. #include <linux/config.h>
    16. 

  16. #include <linux/kernel.h>
    17. 

  17. #include <linux/spinlock.h>
    18. 

  18. #include <linux/module.h>
    19. 

  19. #include <linux/stringify.h>
    20. 

  20. #include <asm/hvcall.h>
    21. 

  21. #include <asm/iSeries/HvCall.h>
    22. 

  22. 

  23. /* waiting for a spinlock... */
    24. 

  24. #if defined(CONFIG_PPC_SPLPAR) || defined(CONFIG_PPC_ISERIES)
    25. 

  25. 

  26. void __spin_yield(spinlock_t *lock)
    27. 

  27. {
    28. 

  28. 	unsigned int lock_value, holder_cpu, yield_count;
    29. 

  29. 	struct paca_struct *holder_paca;
    30. 

  30. 

  31. 	lock_value = lock->lock;
    32. 

  32. 	if (lock_value == 0)
    33. 

  33. 		return;
    34. 

  34. 	holder_cpu = lock_value & 0xffff;
    35. 

  35. 	BUG_ON(holder_cpu >= NR_CPUS);
    36. 

  36. 	holder_paca = &paca[holder_cpu];
    37. 

  37. 	yield_count = holder_paca->lppaca.yield_count;
    38. 

  38. 	if ((yield_count & 1) == 0)
    39. 

  39. 		return;		/* virtual cpu is currently running */
    40. 

  40. 	rmb();
    41. 

  41. 	if (lock->lock != lock_value)
    42. 

  42. 		return;		/* something has changed */
    43. 

  43. #ifdef CONFIG_PPC_ISERIES
    44. 

  44. 	HvCall2(HvCallBaseYieldProcessor, HvCall_YieldToProc,
    45. 

  45. 		((u64)holder_cpu << 32) | yield_count);
    46. 

  46. #else
    47. 

  47. 	plpar_hcall_norets(H_CONFER, get_hard_smp_processor_id(holder_cpu),
    48. 

  48. 			   yield_count);
    49. 

  49. #endif
    50. 

  50. }
    51. 

  51. 

  52. /*
    53. 

  53.  * Waiting for a read lock or a write lock on a rwlock...
    54. 

  54.  * This turns out to be the same for read and write locks, since
    55. 

  55.  * we only know the holder if it is write-locked.
    56. 

  56.  */
    57. 

  57. void __rw_yield(rwlock_t *rw)
    58. 

  58. {
    59. 

  59. 	int lock_value;
    60. 

  60. 	unsigned int holder_cpu, yield_count;
    61. 

  61. 	struct paca_struct *holder_paca;
    62. 

  62. 

  63. 	lock_value = rw->lock;
    64. 

  64. 	if (lock_value >= 0)
    65. 

  65. 		return;		/* no write lock at present */
    66. 

  66. 	holder_cpu = lock_value & 0xffff;
    67. 

  67. 	BUG_ON(holder_cpu >= NR_CPUS);
    68. 

  68. 	holder_paca = &paca[holder_cpu];
    69. 

  69. 	yield_count = holder_paca->lppaca.yield_count;
    70. 

  70. 	if ((yield_count & 1) == 0)
    71. 

  71. 		return;		/* virtual cpu is currently running */
    72. 

  72. 	rmb();
    73. 

  73. 	if (rw->lock != lock_value)
    74. 

  74. 		return;		/* something has changed */
    75. 

  75. #ifdef CONFIG_PPC_ISERIES
    76. 

  76. 	HvCall2(HvCallBaseYieldProcessor, HvCall_YieldToProc,
    77. 

  77. 		((u64)holder_cpu << 32) | yield_count);
    78. 

  78. #else
    79. 

  79. 	plpar_hcall_norets(H_CONFER, get_hard_smp_processor_id(holder_cpu),
    80. 

  80. 			   yield_count);
    81. 

  81. #endif
    82. 

  82. }
    83. 

  83. #endif
    84. 

  84. 

  85. void spin_unlock_wait(spinlock_t *lock)
    86. 

  86. {
    87. 

  87. 	while (lock->lock) {
    88. 

  88. 		HMT_low();
    89. 

  89. 		if (SHARED_PROCESSOR)
    90. 

  90. 			__spin_yield(lock);
    91. 

  91. 	}
    92. 

  92. 	HMT_medium();
    93. 

  93. }
    94. 

  94. 

  95. EXPORT_SYMBOL(spin_unlock_wait);
    96.