rcutiny.h 3.3 KB

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  1. /* SPDX-License-Identifier: GPL-2.0+ */
  2. /*
  3. * Read-Copy Update mechanism for mutual exclusion, the Bloatwatch edition.
  4. *
  5. * Copyright IBM Corporation, 2008
  6. *
  7. * Author: Paul E. McKenney <paulmck@linux.ibm.com>
  8. *
  9. * For detailed explanation of Read-Copy Update mechanism see -
  10. * Documentation/RCU
  11. */
  12. #ifndef __LINUX_TINY_H
  13. #define __LINUX_TINY_H
  14. #include <asm/param.h> /* for HZ */
  15. /* Never flag non-existent other CPUs! */
  16. static inline bool rcu_eqs_special_set(int cpu) { return false; }
  17. static inline unsigned long get_state_synchronize_rcu(void)
  18. {
  19. return 0;
  20. }
  21. static inline void cond_synchronize_rcu(unsigned long oldstate)
  22. {
  23. might_sleep();
  24. }
  25. extern void rcu_barrier(void);
  26. static inline void synchronize_rcu_expedited(void)
  27. {
  28. synchronize_rcu();
  29. }
  30. /*
  31. * Add one more declaration of kvfree() here. It is
  32. * not so straight forward to just include <linux/mm.h>
  33. * where it is defined due to getting many compile
  34. * errors caused by that include.
  35. */
  36. extern void kvfree(const void *addr);
  37. static inline void kvfree_call_rcu(struct rcu_head *head, rcu_callback_t func)
  38. {
  39. if (head) {
  40. call_rcu(head, func);
  41. return;
  42. }
  43. // kvfree_rcu(one_arg) call.
  44. might_sleep();
  45. synchronize_rcu();
  46. kvfree((void *) func);
  47. }
  48. void rcu_qs(void);
  49. static inline void rcu_softirq_qs(void)
  50. {
  51. rcu_qs();
  52. }
  53. #define rcu_note_context_switch(preempt) \
  54. do { \
  55. rcu_qs(); \
  56. rcu_tasks_qs(current, (preempt)); \
  57. } while (0)
  58. static inline int rcu_needs_cpu(u64 basemono, u64 *nextevt)
  59. {
  60. *nextevt = KTIME_MAX;
  61. return 0;
  62. }
  63. /*
  64. * Take advantage of the fact that there is only one CPU, which
  65. * allows us to ignore virtualization-based context switches.
  66. */
  67. static inline void rcu_virt_note_context_switch(int cpu) { }
  68. static inline void rcu_cpu_stall_reset(void) { }
  69. static inline int rcu_jiffies_till_stall_check(void) { return 21 * HZ; }
  70. static inline void rcu_idle_enter(void) { }
  71. static inline void rcu_idle_exit(void) { }
  72. static inline void rcu_irq_enter(void) { }
  73. static inline void rcu_irq_exit_irqson(void) { }
  74. static inline void rcu_irq_enter_irqson(void) { }
  75. static inline void rcu_irq_exit(void) { }
  76. static inline void rcu_irq_exit_preempt(void) { }
  77. static inline void rcu_irq_exit_check_preempt(void) { }
  78. static inline void exit_rcu(void) { }
  79. static inline bool rcu_preempt_need_deferred_qs(struct task_struct *t)
  80. {
  81. return false;
  82. }
  83. static inline void rcu_preempt_deferred_qs(struct task_struct *t) { }
  84. #ifdef CONFIG_SRCU
  85. void rcu_scheduler_starting(void);
  86. #else /* #ifndef CONFIG_SRCU */
  87. static inline void rcu_scheduler_starting(void) { }
  88. #endif /* #else #ifndef CONFIG_SRCU */
  89. static inline void rcu_end_inkernel_boot(void) { }
  90. static inline bool rcu_inkernel_boot_has_ended(void) { return true; }
  91. static inline bool rcu_is_watching(void) { return true; }
  92. static inline void rcu_momentary_dyntick_idle(void) { }
  93. static inline void kfree_rcu_scheduler_running(void) { }
  94. static inline bool rcu_gp_might_be_stalled(void) { return false; }
  95. /* Avoid RCU read-side critical sections leaking across. */
  96. static inline void rcu_all_qs(void) { barrier(); }
  97. /* RCUtree hotplug events */
  98. #define rcutree_prepare_cpu NULL
  99. #define rcutree_online_cpu NULL
  100. #define rcutree_offline_cpu NULL
  101. #define rcutree_dead_cpu NULL
  102. #define rcutree_dying_cpu NULL
  103. static inline void rcu_cpu_starting(unsigned int cpu) { }
  104. #endif /* __LINUX_RCUTINY_H */